Avsnitt
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This episode was recorded at the 2025 Florida Ruminant Nutrition Symposium. Dr. Johnson and Dr. Felix begin with brief descriptions of their background. (1:26)
Dr. Johnson’s presentation at the symposium focuses on beef quality aspects of using beef sires on dairy cows. Using the same Angus semen, his research model compared Angus-sired beef calves raised in a conventional cow-calf system, Angus x Holstein calves, Angus x Jersey calves, and Angus-sired IVF beef embryos transplanted into Holstein and Jersey cows. The model evaluated how the management impacted feedlot performance and carcass quality. (6:37)
Dairy-influenced beef is tender and highly marbled. It also has more oxidative fibers prone to lipid peroxidation and higher myoglobin content which gives it a redder hue. When high-myoglobin beef is in retail packaging, it goes through discoloration faster than traditional native beef, and retailers shy away from that. Beef on dairy products have a retail display life more like native beef, and large retailers are embracing that product. (10:12)
Ribeye size was not different among any of the cattle groups in Dr. Johnson’s study, including straight calf-fed Holsteins. Beef on dairy calves have similar ribeye area and 0.15-0.20 inches less backfat than a straight beef calf, so their yield grades are lower, implying more red meat yield. In practice, however, they don’t have increased red meat yield compared to native beef because they give up so much muscle in their hindquarter. (14:14)
Dr. Felix asks if the selection criteria of the Angus sire Dr. Johnson used may have limited the findings from a yield standpoint. Dr. Johnson agrees that was definitely the case, as they chose a high-marbling sire on purpose, and he happened to be fairly light muscled. Dr. Johnson feels that improving the plane of nutrition of beef on dairy calves in the hutch for the first 60-70 days could vastly improve hindquarter muscling later in life. (19:39)
Muscle biopsies from the ribeye and hindquarter of hutch calves on low and high planes of nutrition found no difference in muscle proliferation in the ribeye. Hindquarter muscle proliferation was improved in calves on the high plane diet. Dr. Felix reiterated that there is a lack of literature in this area. (25:35)
If beef on dairy calves have less backfat, does that mean they have better feed efficiency? In Dr. Johnson’s study, the best feed efficiency group was the Angus x Holstein F1 cross. Dr. Felix and Dr. Johnson discuss changes in feedlot practices and days on feed and how the industry is moving to carcass-adjusted average daily gain and feed efficiency measures. (31:14)
The panelists discussed the impact of gut size on carcass value. In the dairy industry, we want cows to have high intakes for high milk production, which requires a large gut size. Dams of beef on dairy calves may pass on these traits. Dr. Johnson describes a beef calf and a beef on dairy calf out of the same sire where the beef calf was 40 pounds lighter at the end of the feeding period, yet both calves had the same hot carcass weight. That 40-pound difference was gut size. Dr. Felix and Dr. Johnson share their experiences with differences in fat and trim between beef and beef on dairy carcasses. (39:25)
Dr. Felix asks Dr. Johnson how the valuation of beef on dairy calves drives marketing decisions. Day-old dairy calves are extremely valuable right now. A high index beef on dairy calf will bring $800-$1100, depending on what part of the country you live in. If a dairy producer only has $200 in that calf, they should take the money and run. There is no way they will make $800 per head feeding out those calves. (47:30)
In closing, Dr. Zimmerman urges ASAS and ADSA to bring back Joint Annual Meetings so more cross-species interactions can be fostered. Dr. Felix notes there is a tremendous gap where the dairy nutrient requirements end and where the beef nutrient requirements pick up. We need to fill that gap to better target optimal muscle development in beef on dairy calves. Dr. Johnson is enthusiastic about the amount of progress the beef on dairy sector has experienced in a short period. We’re one or two tweaks away from beef on dairy carcasses rivaling native beef in quality. What we’re learning in this sector can also be applied to the native beef sector to improve meat quality and red meat yield. (56:52)
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This episode was recorded at the 2025 Florida Ruminant Nutrition Symposium. Dr. Felix and Dr. Johnson begin with brief descriptions of their background and interest in beef on dairy research. (3:15)
Dr. Felix’s first study in this area compared dairy calves with beef on dairy calves of unknown origin. They were placed in the feedlot and fed and implanted the same. Beef on dairy calves grew faster, but they ate more, so there was no difference in feed efficiency. They also had larger ribeye areas and slightly heavier carcass weights. In subsequent studies, calf growers indicated that beef on dairy calves were more hardy and got a quicker start in the calf systems. (9:16)
Dr. Johnson and Dr. Felix are both fans of using Charolais sires in beef on dairy systems. Dr. Felix emphasizes that while breed can be important, individual sires within breeds really make the difference when it comes to successful beef on dairy systems. (13:23)
The beef and dairy industries speak two different languages when it comes to genetic selection. Dr. Felix encourages education efforts across both segments to speak a common language. Bull studs are heavily invested in this effort. Just 2.5 million units of beef semen were sold in the US in 2017, compared to 9.4 million units in 2024. (16:15)
The use of beef sires increased gestation length by two days in one study of over 10,000 dairy records. Dairy producers may have to manage the dry period of beef on dairy cows differently to avoid loss of milk production. (20:46)
Last year, the National Association of Animal Breeders published a new category in their annual semen sales report: heterospermic beef, at 1.5 million straws. Genetic companies have started to market straws containing semen from two to three different beef bulls who have similar desired traits. The literature suggests that different cows’ reproductive tract environments have different “preferences” for semen. The theory behind heterospermic beef is by putting more than one bull in a straw, we may see increased fertility for that straw. (27:52)
Dr. Felix explains her sire selection process from her USDA research. Regardless of breed, she focused on yearling weight, carcass weight, and ribeye area. Because of this, little difference was found between breeds since the same terminal traits were of priority. Dr. Johnson agrees that the growth of beef on dairy has been beneficial to feedlots and that the beef cattle industry can learn from the beef on dairy systems. (32:36)
What challenges still exist with beef on dairy? Dr. Felix suggests we need to get past the block of dairy beef “only being 20% of the fed cattle” - why shouldn’t that 20% be as high quality as possible? Health will continue to be a challenge, particularly in the areas of liver abscesses and respiratory disease. (41:46)
Adequate colostrum intake is critical for successful beef on dairy calves. Dr. Felix describes a project where calves who had adequate passive immunity were heavier at nine months of age than calves who had failure of passive immunity. Dr. Johnson concurs and reminds listeners that colostrum also contains bioactive components that appear to have value beyond immunity, even after gut closure. (44:36)
Dr. Johnson gives some perspective from the cow/calf side of the beef cattle industry regarding beef on dairy. He feels that there is much to learn from beef and dairy systems that can be applied to the cow/calf sector. Dr. Felix has received pushback from cow/calf producers that she’s trying to “put them out of business.” She counters that we had 20% dairy influence in fed cattle when they were Holstein, and there is still 20% dairy influence now that they’re crossbred cattle. We’re not changing how many calves come from the dairy industry each year, but we are increasing the amount of beef produced. (47:52)
Each panelist wraps up with their take-home messages. Dr. Zimmerman was interested to learn about the longer gestation lengths in beef on dairy crosses and the implications that has for drying off cows. Dr. Johnson reminds listeners not to forget about the maternal side of the beef on dairy industry. He wonders if dairy producers could select for improved muscling without a loss in milk production to make beef-on-dairy crossbred calves even more desirable to the packer. Dr. Felix comments that, at the end of the day, it’s about feeding people. The increase in beef production from beef on dairy is something to be proud of, and she hopes some of what has been learned can also benefit the cow/calf industry to improve sustainability for the entire beef supply chain. (54:16)
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Saknas det avsnitt?
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
Dr. Baumgard begins with an overview of the structure and function of the gastrointestinal tract. More than 75% of an animal’s immune system resides in the gut. The focus of this webinar is how heat stress initiates leaky gut, how that leaky gut then influences the immune and hormonal systems, and ultimately, how that reduces productivity. (0:22)
Dr. Baumgard compares the metabolism of a cow 200 days in milk to a cow 10 days in milk. The 200-day cow is experiencing ad libitum intake and gaining weight. Her insulin levels would be high, and NEFAs would be low. On the other hand, the 10-day cow is experiencing suboptimal intake, and her insulin levels are the lowest they’ll ever be during the production cycle. Body tissue is mobilized, and NEFAs will increase. Research shows it takes 72 grams of glucose to make one kilogram of milk. Any disruption to the gluconeogenic pathway has the potential to decrease milk yield. (6:38)
Heat stress is estimated to cost the US dairy industry $1.7 billion each year. Regardless of climate change, heat stress will continue to be an issue because all economically important phenotypes in animal agriculture are heat-producing processes. Dr. Baumgard’s lab has been investigating the biology of heat stress to implement more effective mitigation strategies. (9:09)
How much of the reduction in feed intake during heat stress explains the reduction in milk yield? A pair-feeding experiment comparing thermoneutral to heat-stressed cows showed that about 50% of the reduction in milk yield during a heat wave is due to a reduction in feed intake. The thermoneutral cows lost weight in response to decreased intake, and their NEFAs increased. Heat-stressed cows did not have an increase in NEFA. Heat-stressed animals fail to mobilize adipose tissue despite their endocrine profile predicting that they should. However, insulin is high when we would expect it to be low, and that response to heat stress is highly conserved in all species. (10:43)
Heat-stressed cows produced about 400 grams less lactose per day than their pair-fed thermoneutral controls. This is nearly a pound! Is the liver producing 400 fewer grams of glucose each day? Or is some other extramammary tissue using more glucose per day? Dr. Baumgard’s work suggests that the immune system is where the 400 grams of glucose go in heat-stressed animals. During heat stress, vasodilation at the body surface occurs, with concomitant vasoconstriction in the gut. The gut epithelium is very sensitive to reduced oxygen delivery that would result from the vasoconstriction, and tight junction proteins do not function properly, resulting in a leaky gut. This results in an infiltration of antigens into the body, which causes an immune response. (15:36)
Dr. Baumgard details how insulin fits into these immune responses via the Warburg effect. An activated immune cell prefers glucose and needs it in high quantities. The activated cell switches from the Kreb’s cycle to generate ATP to aerobic glycolysis. This requires high insulin. The immune system requires approximately one gram of glucose per kilogram of metabolic body weight per hour. (25:03)
By far, the biggest impact a dairy producer can make to alleviate heat stress is to modify the environment physically: shade, fans, soakers, misters, etc. Investing in cooling cows improves production efficiency and profitability, summer fertility, animal welfare and health, and sustainability. Other important heat abatement considerations include adequate water availability, reducing walking distance to the parlor and time in the holding pen, and improving ventilation. Dry cows should also be part of any heat abatement strategy, as the benefits of cooling dry cows extends far into lactation. Dr. Baumgard also discusses different dietary management strategies for heat stress situations. (32:43)
In summary, heat stress decreases almost every metric of productivity and costs everyone in the industry. Reduced feed intake is only part of the problem. Heat-induced leaky gut results in biological consequences incredibly similar to any other immune activation, such as mastitis or metritis. For dairy producers, heat stress abatement should by far be their biggest priority. Once those infrastructure improvements are in place, dietary interventions are another good strategy to minimize the negative consequences of heat stress. (47:43)
Dr. Baumgard takes questions from the webinar audience. (49:22)
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In times of limited forage, dairy producers may need to feed diets lower in forage than is typical but would like to maintain milk production. In this study, two diets similar in neutral detergent fiber (NDF), starch, and crude protein with different amounts of forage were fed to 32 mid-lactation Holstein cows in a crossover design. The control diet (CON) contained high forage (55.5% of diet dry matter) with no supplemental fatty acids or amino acids. The low-forage diet (LF) contained 36.6% forage along with supplemental fat and rumen-protected methionine and lysine. As forage was removed from the LF diet, it was replaced with byproducts and high-moisture corn was replaced with dry corn. (4:42)
Dr. Lock added fat and amino acid supplements to the LF diet to not lose milk production. The fat supplement was a palmitic-acid-rich prill. Dr. Lock does not think the response would have been the same if a different fat supplement had been used. The LF diet was higher in fat and palmitic acid, but most other fatty acids were fairly similar between the two diets. (16:25)
Milk yields were similar between the two diets. Cows on the LF diet consumed about 1 kg more dry matter each day than CON-fed cows. Cows fed the LF diet also had higher milk fat and milk protein yields and content which led to an approximately 2 kg increase in energy-corrected milk compared to cows fed the CON diet. Dr. Lock believes the fat and amino acid supplementation were a key part of achieving these results, and they would not have seen the same response if those supplements had not been added to the LF diet. The LF diet spared around 5.5-6 kg of forage per day, and cows gained body condition. (22:03)
Dr. Weiss asks Dr. Lock to speculate if low-forage diets fed for longer periods would have negative health impacts. Dr. Lock feels that usually production would be negatively impacted by cow health issues, which was not the case here. However, if high-moisture corn had been used in the LF diet, he predicts they would have seen negative impacts. (27:18)
What about low-forage diets for early lactation cows? Dr. Lock suggests looking at diets in other parts of the world where forage is limited and see how dairy producers manage diets in those instances. He speculates that lower forage could be successfully implemented in early lactation cows after the fresh period. (31:09)
Dr. Weiss and Dr. Lock discuss the apparent improved digestibility of the LF diet given the increased production. While byproduct ingredients are often more fermentable in vitro, the results don’t always translate in vivo. Palmitic acid supplementation has been shown to improve fiber digestibility, so that may have happened in this experiment. (32:12)
On the protein side, we’ve moved away from talking about crude protein in the diet and toward amino acid concentrations. Dr. Lock would like to see the same trend in the industry for fat in the diet. A good leap was made recently from ether extract to total fatty acids, and he hopes to see individual fatty acids as the next step in that evolution. He recommends two questions be asked when considering a new fatty acid supplement. What is the fatty acid profile? What is the total fat content? The appropriate fatty acid profile is going to depend on the basal diet and what type of cow is being fed. Dr. Lock’s preference is a palmitic: oleic acid blend around 70:20 or 60:30 early in lactation, with a higher palmitic blend later in lactation. He expects the current work with different oilseeds to provide some good recommendations for feed ingredients to incorporate to increase dietary fat. (35:53)
As genetics continue to improve and nutrient requirements of cows continue to increase, is it conceivable that someday we are going to purposefully decrease fiber in the diet? While that may be the case, Dr. Lock reminds listeners that about half of milk fat comes from acetate and butyrate produced in the rumen, so fiber is still going to be critical. While we may lower the forage in a diet, forage quality is going to remain very important. (39:45)
The panel wraps up with their take-home messages from this paper. Clay looks forward to more research with a factorial design to further evaluate low-forage diets. Dr. Weiss reminds listeners there’s no one recipe for diets to achieve high yields of milk components. Lastly, Dr. Lock is excited about the future of research in this area and refining diet formulation in the area of fat supplementation. (43:21)
You can find this episode’s journal club paper from JDS Communications here: https://www.sciencedirect.com/science/article/pii/S2666910223001084
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
Dr. Santos begins with a timeline of events that occur during the cow’s transition from the dry period to her exit from the fresh pen. He suggests that cows should be dried off at around 230 days of gestation, then moved to a closeup group at 250-255 days gestation which is around three to three-and-a-half weeks before calving. Dr. Santos recommends keeping multiparous cows separate from primiparous cows and feeding to minimize metabolic disorders in early lactation. After calving, cow health needs to be monitored for early detection and treatment of disease. In addition, diets that do not limit voluntary dry matter intake should be fed. During the early postpartum period, controlling excessive weight loss and lipid mobilization is the goal. (00:27)
What is the association between time spent in the closeup pen and disease? Research shows that around three to four weeks in the prepartum group is associated with the lowest risk of morbidity, maximum milk yield and highest pregnancy rates. How does a change in body condition during the first 65 days in milk impact cyclicity? How does 90-day milk yield impact cyclicity? Cows that lose one or more units of condition are less likely to be cyclic at the end of the voluntary waiting period. There is a small statically positive association between milk yield and cyclicity. Dr. Santos’ first take-home message is to avoid excessive body condition loss after calving. Cows should lose no more than 0.5 body condition units from the week before calving to the first AI. This can be accomplished by minimizing over-conditioned cows at dry-off and reducing the risk of disease in early lactation. (6:13)
What about feed efficiency? Dr. Santos describes experiments comparing the 25% most efficient to the 25% least efficient cows. All cows produced the same amount of energy-corrected milk, but the most efficient cows ate four kilograms less feed each day. The risk of morbidity and the culling rate was the same for both groups, as was reproductive performance. Dr. Santos suggests we should not be afraid of selecting for feed efficiency while still optimizing intake in early lactation. (18:23)
Morbidity negatively impacts intake in early lactation. Around one-third of cows are affected by disease in the first three weeks of lactation and almost 80% of the first disease diagnoses occur during the first three weeks postpartum. The earlier in lactation disease occurs, the longer the legacy effects from that disease can impact cow health and performance. Dr. Santos describes an experiment in beef cattle evaluating how an inflammatory response impacts nutrient partitioning away from performance. Early lactation morbidity not only makes a cow not want to eat, it also may shift nutrients away from production toward survival, resulting in fewer nutrients available for milk production and reproduction. Dr. Santos describes a series of experiments evaluating the impact of early lactation disease diagnosis on reproductive performance. Dr. Santos’ second take-home message is to stimulate dry matter intake and minimize disease in the early lactation period. (22:21)
How can we formulate diets that will improve reproduction? First, we should formulate diets that reduce the risk of disease. Then we should incorporate nutrients that are known to improve reproduction in cows. Dr. Santos describes how supplementation with rumen-protected choline decreases triglyceride accumulation in the liver and improves milk yield. He also details the mechanisms of using acidogenic diets to reduce hypocalcemia. He recommends not using these diets for heifers and feeding them for around 21 days to cows rather than the entire dry period. Dr. Santos feels that forage quality has been neglected in the transition period and details how improved fiber digestibility during the transition period can have longer-term impacts. Lastly, he recommends feeding 1-1.5% supplemental fat in early lactation diets for improved reproduction and milk yield without negative impacts on body condition. In closing, Dr. Santos presents a summary of diet formulation recommendations for transition cows. (34:13)
Dr. Santos leads an engaged question-and-answer session with the webinar audience. (51:11)
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In this episode, we honor and celebrate the remarkable career and contributions of Dr. Jim Drackley from the University of Illinois, a pioneer in dairy science and animal nutrition. Jim’s work has reshaped our understanding of dairy cow health, metabolism and nutrition. Dr. Cardoso, Dr. Overton, and co-host Dr. Jeff Elliott are former coworkers or graduate students of Dr. Drackley’s. (0:11)
Dr. Drackley begins by telling the audience about his background and how he became a dairy scientist. He talks about several of his mentors during his schooling. (9:20)
Speaking of mentors, Scott asks Dr. Elliot, Dr. Overton, and Dr. Cardoso to describe Dr. Drackley’s mentorship of them during teaching, graduate school and beyond. They praise Jim’s thoughtfulness and hands-off approach that taught them to think critically. (14:06)
When it comes to major contributions to the industry, Dr. Drackley names two that he is most proud of: expanding the knowledge of controlled energy dry cow programs using straw and corn silage to help control energy intake and his work in baby calf nutrition, specifically feeding more milk on-farm to calves. Dr. Overton adds that a visionary paper Dr. Drackley wrote in the late 1990s where he referred to the transition period as the final frontier as another important contribution. Dr. Cardoso also emphasizes Dr. Drackley’s excellent teaching skills as another achievement of note. (20:58)
Dr. Drackley says the teaching part of the job was the part that scared him the most when he started. Graduate school offers little formal teaching training and experience so one learns on the job. Jim describes his teaching style as organized, and he liked teaching in an outline fashion, working from the main topic down through the details. He worked hard to get to know the students, learn their names as soon as possible, and be approachable and empathetic. Later in his career, he used a flipped classroom approach for a lactation biology course and enjoyed it. (28:45)
The panel then reminisces about how much technology has changed from a teaching perspective as well as statistical analysis. Lecturing has moved from chalkboard to overhead projector to slide carousel to PowerPoint. Statistical analysis has moved from punch cards or sending data to a mainframe computer to performing real-time statistical analysis on your computer at your desk. (33:00)
Jeff, Phil, and Tom share stories and memories of their time with Jim. (37:30)
Scott asks Jim what challenges will need to be tackled in the future in the dairy industry. He lists environmental aspects (nitrogen, phosphorus, and greenhouse gases), increasing economic pressure on farms, and improving forage production and efficiency of nutrient use. Dr. Drackley’s advice for young researchers is to carve out a niche for yourself. (47:40)
Dr. Elliott, Dr. Overton, and Dr. Cardoso share some final thoughts paying tribute to Dr. Drackley and his accomplished career. (1:06:18)
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
How can we increase milk protein and capture that income opportunity? Dr. Van Amburgh describes the seasonal drop in milk protein observed in the summer months. Heat stress may play a role in altering insulin sensitivity and how the cow partitions nutrients. What can we do to avoid that seasonal decline in milk protein? (0:01)
Simple things like cooling, fans, and sprinklers can reduce heat stress and increase cow comfort. Dr. Van Amburgh recommends promoting dry matter intake and lying time, with feed available 21-22 hours per day and more than 12 hours of lying time per day. (5:27)
Dr. Van Amburgh discusses basic formulation considerations for amino acid balancing including current feed chemical analyses that include NDF digestibility, characterizing the cows appropriately by using accurate body weights, understanding DMI and making sure actual milk lines up with ME and MP allowable milk, assessing body condition changes, and understanding the first limiting nutrient of milk production. Areas where mistakes are often made include using much lighter body weights than actual to formulate rations, not using actual DMI, and using feed library values instead of actual feed chemistry. (8:00)
Milk protein percentage and dietary energy are closely aligned. This is often attributed to ruminal fermentation and microbial yield. Sugars, starches, and digestible fiber sources drive microbial yield. While protein and energy metabolism are considered to be separate, that is an artificial divide and they should be considered together. Once adequate energy for protein synthesis is available, providing more dietary protein or amino acids can increase protein synthesis further. Dr. Van Amburgh provides some ranges of target fermentable non-structural carbohydrates, starch, sugar and soluble fiber appropriate for early peak and mid-lactation cows. He speaks about the benefits of adding sugars to the diet instead of trying to continue to increase starch. (11:15)
Dr. Van Amburgh details an experiment using more byproduct feeds in a lactation diet to successfully increase intake and subsequently, milk protein content. (24:04)
Milk protein increases with higher DCAD in diets, independent of protein level. Increasing DCAD can also lead to increased DMI, probably through better fiber digestion. The mechanism is not completely understood, but perhaps some rumen microbes have a higher requirement for potassium. In another study, feeding higher DCAD resulted in an 11% increase in milk protein yield and a 26% increase in milk fat yield. (32:39)
Feeding fatty acids may also improve milk protein via insulin signaling pathways. A 5.6% increase in milk protein was observed when the ratio of palmitic acid to oleic acid was around 1.5:1. (36:21)
Dr. Van Amburgh encourages the audience to pay close attention to digestibility of dietary ingredients and shares an analysis of ten different sources of feather meal that varied in digestibility from around 50% up to 75%. (40:10)
Dr. Van Amburgh details an experiment targeting optimum methionine and lysine levels for improved milk protein. In an example with 60 Mcals of ME in the diet, the targets were 71 grams of methionine and 193 grams of lysine. (42:00)
Questions from the webinar audience were addressed. They included information about the best type of sugars to add to diets, if protozoa are preferentially retained in the rumen, BMR vs conventional corn silage, amino acid supply when dietary crude protein is around 14-15%, using metabolizable energy instead of net energy, variability of animal protein blends, and methionine to lysine ratios. (48:23)
To end this podcast, Dr. Jose Santos steps in to invite everyone to the Florida Ruminant Nutrition Symposium in Gainesville held February 24-26.
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In this study, two basal diets were fed, one low-fat and one high-fat. The low-fat diet contained cottonseed meal and cottonseed hulls and the high-fat diet contained whole cottonseed. This balanced fiber and protein to try and make the difference between the basal diets and just the fatty acids. Basal diets were supplemented with two different fat supplements that had different ratios of palmitic and oleic acids. The applied question at hand was “Does fat need to be supplemented to a high-fat basal diet?” (5:32)
The low-fat diet contained 1.93% fatty acids and the high-fat diet contained 3.15% fatty acids. Fatty acid supplements were fed at 1.5% of dry matter and replaced soyhulls. The palmitic acid supplement contained 80% palmitic acid and 10% oleic acid. The palmitic + oleic acid supplement contained 60% palmitic acid and 30% oleic acid. Thirty-six cows were used in a split-plot Latin square design, with half the cows on each basal diet. Under each split-plot, cows were allocated to a 3x3 Latin square, evaluating a control treatment (no fat supplement), palmitic acid supplement, and palmitic + oleic acid supplement. (8:46)
Bill, Adam, and Clay discuss the increase in milk components the industry has experienced recently due to the powerful combination of genetics and nutrition. Hoard’s Dairyman reported that 2024 was the first year that the U.S. had averaged over 4% milk fat going back to 1924 when records began. (13:01)
Both fat supplements increased milk yield in low-fat and high-fat basal diets, but the magnitude of the increase was larger in the low-fat diet. The high palmitic acid diet increased milk yield more in cows fed the low-fat basal diet than the palmitic + oleic supplement did. High-fat basal diet cows had similar milk yield responses to both fatty acid supplements. The panel discusses the industry emphasis on milk components and if/when a threshold in performance might happen given the advancement of genomics and nutrition. (15:51)
Clay asks Adam to remind the listeners about the relationship between fatty acids and crude fat or ether extract. Adam recommends moving away from ether extract and focusing solely on fatty acid content. Bill, Adam, and Clay talk about the variability in the fatty acid content of various feedstuffs. (25:33)
Bill asks if the feed efficiency improvement with the fat supplementation was due to more of a gross energy or digestible/metabolizable energy effect. Adam suggests it may be a little of both. The diet is more energy-dense, but we also know now that some of those specific fatty acids have specific effects. Improvements in NDF digestibility are consistently observed with palmitic acid supplementation. Oleic acid improves fatty acid absorption and has an impact on adipose tissue metabolism and insulin sensitivity. Bill and Adam go on to talk more philosophically about the best way to measure feed efficiency in dairy cows. (29:02)
If Adam could do this experiment over again, he would have pushed the basal fat levels a bit more and had both lower-producing and higher-producing cows in the experiment. This leads to a discussion of how the results might have differed if distiller grains or soybeans were used instead of cottonseed in the experiment. Listeners should be careful not to extrapolate the results from this experiment to other fat sources. (33:55)
Adam emphasizes that we shouldn’t be afraid of feeding high-fat diets, either basal or supplemental fatty acids, especially to high-producing cows. We should be very mindful about where those fatty acids are coming from. We could provide the same nutrients by feeding either cottonseed or distillers grains, but how those ingredients feed out could be very different. (38:38)
In summary, Clay agrees we should take a fresh look at how much fat we’re feeding cows in basal diets and underlines the importance of the source of supplemental fatty acids. Bill concurs and commends Adam’s group for basically making cottonseed without fat in the low-fat basal diet, which allowed for very clean interpretations of the fatty acid supplement results. Adam underlines that we can feed higher fat diets, but the fatty acid profile of all of those ingredients we might use is going to be key. In addition to fatty acids in diets and supplements, de novo synthesis of milk fat from acetate is the other half of the equation. Bringing those together might be a strategy to keep up with genetic improvements and drive higher milk fat yield. (47:43)
You can find this episode’s journal club paper from JDS Communications here: https://www.sciencedirect.com/science/article/pii/S2666910223001114
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
Feeding rumen-protected choline in early lactation has consistently increased milk yield and energy-corrected milk yield, which is more pronounced when cows are fed diets low in metabolizable methionine. Choline feeding also increases milk fat and protein yield, minimizes body condition loss in early lactation, and reduces postpartum disease incidence. Dr. McFadden presents three topics about choline biology in the dairy cow. (01:45)
Why should we consider fatty acid feeding when feeding methyl donors like choline and methionine?Choline degradation in the rumen and small intestine, focusing on the role of triethylamine oxide Why should we consider lysophosphatidylcholine as an immunomodulator in fresh cows and preweaning calves?Fatty acid nutrition to optimize methyl donor efficiency. (4:02)
Fatty liver is a concern for fresh cows because of its relationship with ketosis, poor fertility and compromised milk production. Cows with fatty liver exhibit low circulating concentrations of phosphatidylcholine, which is a component of very low-density lipoproteins (VLDL) that transport triglycerides out of the liver. Feeding rumen-protected choline lowers liver triglyceride deposition by supporting the synthesis of phosphatidylcholine and thus, VLDL.
Dr. McFadden goes on to explain the two different pathways for phosphatidylcholine in the liver and how those interact with fatty acid metabolism. He describes several experiments that have investigated how rumen-protected choline and supplemental fatty acids interact in lactating cows.
Low phosphatidylcholine supply is a key feature of fatty liver in dairy cows, likely due to low polyunsaturated fatty acid (PUFA) and low choline supplies. Delivery of post-ruminal PUFA may support phosphatidylcholine synthesis with accompanying improvements in insulin sensitivity, body condition maintenance, and inflammation, but interactions with dietary fatty acid digestibility should be considered. Dr. McFadden gives a list of considerations for fresh cow diets incorporating fat and choline supplementation.
Gastrointestinal choline degradation and trimethylamine N-oxide (TMAO) (16:58)
Unprotected choline is almost totally degraded in the rumen. Microbes convert choline into trimethylamine (TMA) which is then converted to TMAO in the liver. Rumen-protected choline allows for a large proportion of choline to reach the small intestine intact. However, research shows that choline can also be degraded by microbes in the small intestine in the same pathway, limiting choline bioavailability. Plasma TMAO accumulation is associated with non-alcoholic fatty liver disease, inflammation, insulin resistance, obesity, oxidative stress, and cardiovascular disease in rodent and human models. Little research was available regarding if the relationship between TMAO and poor health was causative or just associative. Dr. McFadden’s lab infused cows intravenously with TMAO and found that TMAO did not modify milk production or glucose tolerance in early lactation cows.
TMAO does not appear to influence energy metabolism or health in early lactation cows. Choline is subject to both ruminal and lower-gut degradation to TMA, and that influence on choline bioavailability needs to be defined. Data in non-ruminants suggests that unsaturated fatty acid feeding can shift the gut microbes to slow TMA formation.
Lysophosphatidylcholine and immunomodulation (28:45)
Dr. McFadden gives an overview of neutrophil activation and the oxidative burst that contributes to pathogen killing. The ability to elicit the oxidative burst is diminished in pre-weaned calves and transition cows. When cows were given endotoxin to cause an immune response, circulating lysophosphatidylcholine was decreased. In rodent models, lysophosphatidylcholine promotes the oxidative burst and suppresses long-term inflammation in response to bacterial infection. Dr. McFadden cultured neutrophils from pre-weaned calves with lysophosphatidylcholine and observed an enhanced oxidative burst.
Immunosuppression is characterized by low circulating lysophosphatidylcholine concentrations in dairy cows. In vitro data suggests lysophosphatidylcholine can activate neutrophils, and rumen-protected choline increases circulating lysophosphatidylcholine. Future research is likely to define an immunomodulatory role for choline.
Dr. McFadden takes questions from the webinar audience. (38:07)
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Dr. Hernandez recently presented a Real Science Lecture series webinar on this topic. You can find the link at balchem.com/realscience.
Dr. Hernandez begins with an overview of how she came to study calcium metabolism in the mammary gland. Over the past number of years, she has worked on research to manipulate what’s happening in the mammary gland in the prepartum period to ensure adequate endocrine, nutritional, reproductive, and immunological status. (5:55)
The panelists discuss how “normal” has changed when it comes to transition cow health. Dr. Overton reminds listeners that 25 years ago, 6-8% of fresh cows in a herd having clinical milk fever was pretty typical. Now, we accept none of that. Subclinical hypocalcemia was not on the radar then, and we thought we had calcium all figured out. Dr. Hernandez’s work shows that this was not the case. She is pleased that a synergism of producers, veterinarians, and academics have been working together to understand the mechanisms of calcium metabolism to find solutions for individual farms based on their situation. (9:22)
Dr. Hernandez then discusses various interventions used in the industry, including low-potassium diets, negative DCAD diets, and zeolite clays. The clays are new to the US, and it seems that they work primarily through a phosphorus reduction mechanism and are best limited to feeding 10-14 days pre-calving. (18:14)
Dr. Overton asks Dr. Hernandez about a point in her webinar that cows are in negative calcium balance through 150-200 days in milk. She confirms that there are approximately 8.5 kilograms of calcium in the bones of a cow, but we don’t know how much of that she loses each lactation. Her dream scenario would be a CT scanner large enough to fit a dairy cow in to evaluate how her bones change throughout lactation. This leads to a discussion of whether or not we should be including higher rates of calcium in dairy cow diets. Dr. Hernandez would like to learn more about what’s happening with calcium absorption in the gut in real-time with endocrine status and stage of lactation, which is a challenging task. (23:17)
Co-host, Dr. Jeff Elliott, asks if the reason multiparous cows are more prone to milk fever is because they’re not as efficient at calcium resorption to the bone. Dr. Hernandez doesn’t have a definitive answer, but it could be due to less effective gut absorption with age, or it may be related to the influence of estrogen on bone density. She also mentions it could be endocrine-controlled or even stem cell-related. (28:59)
Dr. Hernandez’s hypothesis has always been that you have to have a calcium decrease to trigger the negative feedback loop involved in calcium metabolism. Her advice is to wait until 48 hours to take a blood sample to analyze calcium. This aligns well with epidemiological research on the veterinarian side regarding delayed, persistent, transient, and normal hypocalcemic animals. (33:04)
Dr. Overton asks about a calcium-chelation study that Dr. Hernandez’s group conducted and whether or not chelating calcium had an impact on colostrum production. It did not in that experiment. Dr. Hernandez was surprised at how much chelating agent was needed to overcome the draw of the mammary gland, but that further underlines how much of a priority lactation is in metabolism. (41:45)
Scott asks both panelists their views on what the priority should be for research in this area. Dr. Hernandez’s ideas include more research on how zeolite clays work biologically, finding out what’s happening in the gut, mammary gland, and bone of a dairy cow at different stages of lactation. She emphasizes that research should be conducted at different stages rather than just extrapolating from one stage to another because lactation is incredibly dynamic. Dr. Overton seconded the idea of a better understanding of zeolite clays and their feeding recommendations, as well as research defining what happens to and where all the calcium is pulled from the bone during lactation. (45:32)
In closing, Jeff, Tom, and Laura share their take-home thoughts. Jeff is excited to learn more about how zeolite clays work and if other products may come to the forefront to help in calcium metabolism management. Tom commends Laura on her work and how it has dovetailed so well with the epidemiological research from the veterinary side. Laura reminds listeners that the mammary gland is running the show and is thrilled that her work as a basic scientist is having an applied impact on the dairy industry. (51:17)
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Please note the recording was before the new NASEM model was released. However, there is still a lot of good information from Dr. Weiss beyond those recommendations. This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
Most ration formulation software uses the 2001 NRC mineral equations. The basic concept of the 2001 NRC mineral requirements is to feed enough absorbable minerals to maintain adequate labile body stores and fluid concentrations. Minerals are lost each day via excretion in feces and urine, milk production, and incorporation into tissues or the fetus in the case of growing or pregnant animals. We have decent data to predict mineral concentrations of milk, growth, and the fetus; however, the endogenous loss in feces is much harder to capture. Absorption coefficients (AC) for most minerals are exceedingly difficult to measure. (0:29)
The NRC requirements are the means of several experiments. Feeding to the mean results in half the cows being fed adequately or in excess, and half are not fed enough. In human nutrition, recommended daily allowances for vitamins and minerals are calculated as the mean plus two standard deviations, which statistically meets the requirement for 97% of the population. Since the standard deviation of the requirement is hard to acquire, human nutrition uses the same standard deviation for energy metabolism, around 20%. Dr. Weiss feels this is a reasonable safety factor for minerals for animals as well. He recommends feeding about 1.2 times the NRC requirement while keeping an eye on the maximum tolerable limit for the mineral in question. (4:59)
How do we measure absorption? We measure the minerals in the diet, we apply AC, and we get grams or milligrams of absorbed minerals available for the animal to use. Dr. Weiss details some of the complex methodology involved in trying to obtain AC. Feces contain not only unabsorbed dietary minerals but also endogenous/metabolic minerals (e.g., intestinal cells, enzymes, etc.) and homeostatic excretion of minerals (e.g., dumping excess minerals). In the 2001 NRC, the endogenous fecal for almost every mineral is a function of body weight, which is incorrect. It should be a function of dry matter intake. (8:40)
Endogenous fecal losses can also be measured using stable or radioactive isotopes. This method is extremely expensive and if radioactive isotopes are used, management of radioactive waste becomes an issue. Thus, most of the AC for trace minerals that used these methods are 50-60 years old. (15:33)
Dr. Weiss details some of the issues with calcium requirements in the 2001 NRC leading to overestimation of calcium absorption for many calcium sources and overestimation of the maintenance requirement due to endogenous fecal being calculated using body weight. Organic and inorganic phosphorus have different AC, so partitioning between organic and inorganic will give a more accurate estimate of the requirement. (16:33)
Potassium has a linear antagonistic effect on magnesium. You can feed more magnesium to overcome this antagonism, but you won’t ever eliminate it. If you feed a few percent added fat as long-chain fatty acids, Dr. Weiss recommends feeding 10-20% more magnesium to account for soap formation in the rumen. (19:17)
It’s much more difficult to measure AC for trace minerals due to multiple antagonists, interactions among different minerals, and regulated absorption. In addition, AC for trace minerals is very low, which means a small change in the AC can have a huge impact on diet formulation. All feeds in the NRC system have the same AC for each trace mineral and we know that’s not right. (25:39)
Dr. Weiss gives an overview of different trace mineral antagonisms and interactions and details his approach to formulation if he has absorption data for a particular ingredient. He also gives his estimates of revised AC for several minerals. (28:07)
In summary, the factorial NRC approach only fits 50% of the population. Feeding an extra 10-20% above the NRC requirement includes about 97% of the population. We need to continue to account for more sources of variation in AC. Interactions need to be top of mind when considering mineral requirements and diet formulation. (37:39)
Dr. Weiss takes a series of questions from the webinar audience. (40:50)
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.
Feeding behavior of dairy cows is inherently tied to their dry matter intake (DMI) which is tied to milk production. If we want to change a cow’s DMI, it must be mediated by changing her feeding behavior. (00:23)
In a multi-variable analysis, Dr. DeVries found that DMI was most associated with feeding time and meal frequency. It’s important to allow the cow to maximize the amount of time she can spend at the bunk eating, as well as the number of times she can get to the bunk each day. In one study, about 30% of the variability in milk fat content in cows on the same diet was explained by their meal frequency, where cows who had more meals per day had higher milk fat. Dr. DeVries also talks about the impacts of feeding behavior on cow efficiency and rumen dynamics. (2:13)
As soon as a cow sorts the TMR put in front of her, she consumes a diet that’s variable in composition to what we expect. Cows who sorted against long feed particles had lower milk fat and milk protein concentrations. In another study, Dr. DeVries retrospectively analyzed cows with a low vs high risk of ruminal acidosis. Cows in both groups had similar DMI but a tendency for high-risk cows to have lower milk yield and numerically lower milk fat. Combining these resulted in significantly lower fat-corrected milk for the high-risk cows. Given that the diets and DMI were similar, the difference was attributed to sorting, which can have quite negative impacts on individual and herd-level production. (10:00)
Cows spend nearly twice as much time ruminating as they do eating. Rumination reduces feed particle size and increases surface area, leading to increased rates of digestion and feed passage. In a recent study, Dr. DeVries’ group calculated the probability that cows were ruminating while lying down using automated monitoring data from previous experiments. Cows with a higher probability of ruminating while lying down had higher DMI, milk fat, and milk protein than cows who ruminated while standing. This highlights that cows need not only time to ruminate but also space for sufficient rest. (16:44)
Diets and diet composition should be formulated to encourage frequent meals, discourage sorting, and stimulate rumination. Forage management factors including forage quality, forage quantity, forage type (dry vs ensiled), and particle size all play important roles. In a study with fresh cows, Dr. DeVries’ lab fed two different particle sizes of straw: 5-8 cm vs 2-3 cm in length. While DMI was the same over the first 28 days of lactation, cows fed the long straw spent more time with rumen pH below 5.8 because they were sorting against the straw. This also resulted in a yield difference, as the short straw-fed cows produced about 165 pounds more milk over the first 28 days compared to the long straw group. Dr. DeVries also comments on the use of feed additives on rumen stability and feeding behavior (22:54)
More frequent feed delivery should generate more consistent consumption and better feeding behavior, and improve rumen health and milk component concentration. Shifting feed delivery away from return from milking, while still ensuring cows have abundant feed available, results in more consistent eating patterns. Dr. DeVries emphasizes that we push up feed to make sure it’s present at the bunk, not to stimulate cows to eat. We want to make sure that eating behavior is driven by the cow: when she's hungry and goes to the bunk, we need to make sure feed is there. (30:02)
Dr. DeVries indicates we want to minimize the time cows are without feed completely. An empty bunk overnight plus a little overcrowding resulted in negative impacts on rumen health, including more acidosis and reduced fiber digestibility. Increased competition in overcrowding scenarios results in cows having larger meals, eating faster, and likely having a larger negative ruminal impact. In another study, every four inches of increased bunk space was associated with about 0.06% greater milk fat. Herds with high de novo fat synthesis were 10 times more likely to have at least 18 inches of bunk space per cow. (40:04)
In closing, Dr. DeVries’ biggest takeaway is that how cows eat is just as important as the nutritional composition of the feed in ensuring cow health, efficiency, and production. Collectively, with good quality feed and good feeding management, we can gain optimal performance from those diets. Dr. DeVries ends by taking questions from the webinar audience. (43:40)
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Dr. Weiss and Dr. St-Pierre co-authored this episode’s journal club paper in Applied Animal Science (ARPAS Journal). Bill and Normand share a career-long interest in how feedstuffs and diet variation impact cows. (6:31)
Bill and Normand discuss sources of variation, which they divide into true variation and observer variation. True variation means the feed has changed: a different field, change during storage, etc. Observer variation includes sampling variation and analytical variation. Some feeds may exhibit a lot of true variation and others may exhibit a lot of observer variation. And some feeds are high in both types of variation. Highly variable feeds should be sampled more frequently. Some feeds are so consistent that using book values makes more sense than sending in samples for analysis. Bill and Normand go on to give some examples and share sampling and analysis tips for different types of feedstuffs. (12:41)
Bill would often be asked if users should continue to average new samples with older ones or just use the new numbers from the most recent sample. He and Normand debate the pros and cons of the two approaches as well as discuss the use of a weighted average where recent samples would be weighted to contribute more. (26:02)
Next, our guests discuss how multiple sources of a nutrient reduce the TMR variation for that specific nutrient. For example, alfalfa NDF is more variable than corn silage NDF on average. Yet if you use a blend of these two ingredients, you end up with less variation in NDF than if you used all corn silage. Normand details the mathematical concepts behind this relationship. Both Bill and Normand emphasize that diets must be made correctly for the best results. (32:26)
How do feedstuffs and diet variations impact cows? Both guests describe different experiments with variable protein and NDF concentrations in diets. Some were structured, like alternating 11% CP one day and 19% CP the next for three weeks. Some were random, like randomly alternating the NDF over a range of 20-29% with much higher variation than we’d ever see on-farm. The common thread for all these experiments is that the diet variations had almost no impact on the milk production of the cows. (38:04)
Clay asks how variation in dry matter might affect cows. Bill describes an experiment where the dry matter of silage was decreased by 10 units by adding water. Cows were fed the wet silage for three days, twice during a three-week study. To ensure feed was never limited, more as-fed feed was added when the wet silage was fed. It took a day for cows on the wet silage treatment to have the same dry matter intake (DMI) as the control cows and milk production dropped when DMI was lower. However, when switching abruptly back to the dry silage diet, DMI increased the day following the wet silage and stayed high for two days, so the cows made up for the lost milk production. Bill and Normand underline that it is critical for the cows not to run out of feed and described experiments where feed was more limiting, yielding less desirable outcomes. (46:17)
In the last part of the paper, our guests outlined seven research questions that they feel need to be answered. Normand shares that his number one question is how long will cows take to respond to a change in the major nutrients? He feels that we spend an inordinate amount of money on feedstuffs analysis, and there are some feeds we should analyze more and some feeds we should quit analyzing. Bill’s primary research question revolves around controlled variation. What happens if you change the ratio of corn silage and alfalfa once a week? Will that stimulate intake? Data from humans, pets, and zoo animals indicate that diet variation has a positive impact and Bill finds this area of research intriguing. (50:43)
In closing, Clay encourages listeners to read this paper (link below) and emphasizes the take-home messages regarding sampling and research questions. Normand advises that if you are sampling feed, take a minimum of two samples, and try as much as you can to separate observer variation from true variation. He also reminds listeners to concentrate on a few critical nutrients with more repeatability for analyses. Bill encourages nutritionists to sit down and think when they get new data - before they go to their computer to make a diet change. If something changed, why did it change, and is it real? Take time to think it through. (1:01:38)
You can find this episode’s journal club paper from Applied Animal Science here: https://www.appliedanimalscience.org/article/S2590-2865(24)00093-4/fulltext
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This Real Science Exchange episode was recorded during a webinar, which was part of a series. Watch all the presentations from this series here: https://balchem.com/animal-nutrition-health/resources-categories/real-science-lecture-series/previous-lectures/page/10/
Early in lactation, the cow is incapable of eating enough to meet her dramatically increased requirements. As the cow’s intake decreases near calving, there are fewer nutrient contributions from dry matter intake and she must alter nutrient partitioning to meet her increased needs by mobilizing fat and muscle stores. (1:18)
Triglycerides from fat stores are broken down into non-esterified fatty acids (NEFA) and glycerol. NEFA has two different fates in the postpartum cow: to the mammary gland as a precursor for milk fat synthesis, or to the liver to be oxidized for energy production. Glycerol enters the gluconeogenic pathway in the liver as a glucose precursor. (4:41)
The capacity for the liver to use NEFA for energy is limited by the capacity of the TCA cycle. When the TCA cycle is at capacity, excess NEFA can either undergo incomplete oxidation to ketones or be repackaged back into triglycerides. If the capacity for other tissues to use ketones for energy is exceeded, then blood concentrations of ketones rise and negative outcomes from subclinical and clinical ketosis can occur. If triglycerides accumulate in the liver, negative outcomes associated with fatty liver can occur. Triglycerides can be transported out of the liver via very low-density lipoprotein (VLDL) export; however, VLDL export does not keep up with triglyceride concentration during the transition period in dairy cows, largely because of a limiting amount of phosphatidylcholine. (5:51)
Dr. White describes a series of experiments in her lab using liver cells in culture to investigate the relationship between choline supplementation and VLDL export. As choline supplementation to the cell culture increased, so did VLDL export from the cells into the media. In addition, increasing choline supplementation to the cell culture also decreased cellular triglyceride content. (10:54)
Using gene expression and radiolabeled tracers over a series of experiments, Dr. White’s group found that as choline supplementation increased, so did complete oxidation of NEFA to energy. This was accompanied by decreased incomplete oxidation to ketone bodies and decreased accumulation of lipids in the liver cells. Glucose and glycogen were also increased with increasing choline supplementation to the cell culture, and a decrease in reactive oxygen species was observed. In addition, choline-supplemented cultures exhibited an increase in metabolic pathways associated with methionine regeneration and methyl donation. (15:29)
Dr. White then details the complexity of the metabolic pathways that intersect between choline and methionine. In similar experiments supplementing cell cultures with increasing amounts of methionine and choline, there were no effects of methionine on lipid export, oxidative pathways, or glucose metabolism. The main benefit of methionine was a marked increase in glutathione production. It’s important to note that no interactions between choline and methionine were observed in this series of experiments. (19:37)
There seems to be a clear biological priority for different sets of pathways for choline and methionine. Choline seems to be influencing lipid, glucose, and oxidative pathways, while methionine is primarily serving its role as an essential amino acid for cellular protein structure and generation, acting as a methyl donor, and impacting inflammation. Importantly, both the choline and methionine results observed in cell culture are paralleled in transition dairy cow studies. (24:14)
Dr. White’s lab further investigated the impact of methionine on inflammation. When cells were challenged with LPS to provoke an inflammatory response, methionine mitigated the inflammatory response. Similar results have been observed in liver tissue samples of transition cows. Methionine mitigated inflammatory markers and increased glutathione but did not influence reactive oxygen species. Conversely, choline decreased reactive oxygen species but did not change glutathione. (27:47)
Choline and methionine are both essential nutrients, there are biological priorities for them as methyl donors, and they are not mutually exchangeable. The lack of interaction between choline and methionine in vivo or in vitro supports the idea of different biological roles for these nutrients. (32:09)
Dr. White takes questions from the webinar audience. (34:53)
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In part two of a two-part series, the Balchem technical team selected industry research of interest from the 2024 American Dairy Science Association meetings to feature on this episode of the Real Science Exchange.
Smart Cows, Smart Farms: Unleashing the Potential of Artificial Intelligence in the Dairy Sector
Guest: Dr. Jeffrey Bewley, Holstein Association USA (1:58)
Dr. Bewley is the Dairy Analytics and Innovation Scientist at Holstein Association USA, where part of his role is collaborating with Western Kentucky University at the WKU Smart Holstein Lab. The group works with more than 30 technologies, including wearable, camera and machine vision, milk analysis, and automation technologies. At ADSA, Dr. Bewley’s presentation was part of a symposium titled “Applications of AI to Dairy Systems.” His talk focused on cow- and farm-level technologies using artificial intelligence. He anticipates a continued massive increase in the availability of technologies for dairy farms to assist with automating processes that are often monotonous tasks. One example of this is the wearable accelerometer technologies that allow for the assessment of estrous behavior, as well as rumination and eating behavior. In the future, camera-based technologies may become more commonplace for things like body condition scoring. Cameras may also be able to monitor rumination and eating behavior, and even perhaps dry matter intake. Dr. Bewley also sees an opportunity on the milk analysis side to be able to measure even more biomarkers to better manage for improved health, reproduction, and well-being. He reminds listeners that animal husbandry will continue to be a critical piece of dairy farming even with advancing technology. He gives examples of current and cutting-edge technologies on the horizon for dairy farms. On his wish list of technologies for the future, he includes dry matter intake measurement and inline measurement of somatic cell count, hormones, and metabolites in the milk. In closing, Dr. Bewley encourages listeners to be excited yet cautious about artificial intelligence and gives examples of how technology can collect phenotypic data to use in genetic evaluation.
Explaining the Five Domains and Using Behavioral Measures in Commercial Systems
Guest: Dr. Temple Grandin, Colorado State University (26:48)
Dr. Grandin’s presentation was also part of a symposium, titled “The Animal Behavior and Wealthbeing Symposia: Evaluating Animal Comfort and Wellbeing Using the Five Domains.” The five domains approach is gaining popularity. Previous guidance documents emphasized preventing suffering, cruelty, and discomfort. The five domains are nutrition, environment, health, behavior interactions, and the emotional state of the animal. Much of the information available is very theoretical. Dr. Grandin’s goal for this presentation was to gather easy-to-download scoring tools to assist in auditing the five domains in the field. She emphasizes the importance of good stockmanship for animal well-being and cautions that while artificial intelligence technologies can be used to assess the five domains, good stockmanship will always be necessary. Dr. Grandin recommends a three-legged audit: internal, independent third-party, and corporate representatives. She cautions against farming all audits out to a third party and anticipates that it has the potential to cause major supply chain disruptions. Lastly, Dr. Grandin recommends simple yet effective outcome measures for audits that can be taught in a short training session that includes practice audits.
View her five domains paper here: https://pubmed.ncbi.nlm.nih.gov/36290216/
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Nutritionists are often blamed for transition cow problems like high NEFAs, clinical and subclinical ketosis, and subclinical hypocalcemia. Dr. Baumgard suggests these symptoms are a result of one of two situations: 1. These are highly productive, healthy, and profitable cows; or 2. The symptoms are the metabolic reflection of immune activation, likely stemming from metritis, mastitis, pneumonia, or GI tract inflammation. In the first scenario, the nutritionist deserves a raise; in the second, these are mostly management issues not caused by nutrition. (1:26)
If listeners are interested in more detail on this topic, Dr. Baumgard suggests reading this 2021 review in the Journal of Dairy Science: “ Invited review: The influence of immune activation on transition cow health and performance—A critical evaluation of traditional dogmas.”
Link: https://www.sciencedirect.com/science/article/pii/S0022030221006329
Dr. Baumgard highlights key concepts that underpin his thinking regarding transition cows: The best indicators of health are feed intake and milk yield, it’s too easy to overthink the immune system, Mother Nature is rarely wrong, and inconsistent or non-reproducible data should create doubt. He goes on to review the incidence of metabolic disorders in early lactation and the energy balance dynamics of the transition period. (4:29)
For decades, we’ve had the assumption that NEFAs and ketones are causing many of the health issues in transition cows. NEFAs, BHBs, and calcium have been correlated and associated with negative outcomes. However many other studies do not find these negative correlations or associations. Plasma NEFA is markedly increased following calving in almost all cows, yet only 15-20% get clinical ketosis. Dr. Baumgard suggests that it’s presumptuous and reductionist of us to assume we can use one metabolite to diagnose the disease. Little mechanistic evidence exists to explain how these symptoms cause metabolic disease issues. (10:29)
If hyperketonemia, high NEFA, and subclinical hypocalcemia are causing disease, then therapeutically treating these disorders would improve overall cow health. NAHMS data does not back that up. Dr. Baumgard dissects the dogma of ketosis. In short, mobilization of adipose tissues and partial conversion of NEFA to ketones is essential for maximum milk yield. (18:35)
High-producing cows are more hypoinsulinemic compared to low-producing cows, and transition period insulin concentrations are inversely related to whole lactation performance. Low insulin concentrations coupled with insulin resistance allow for fat mobilization. (29:02)
Post-calving inflammation occurs in all cows. Sources include the mammary gland, the uterus, and the gut. Severe inflammation precedes the clinical presentation of the disease. In one experiment, all cows exhibited some inflammation in very early lactation. However, cows that were culled or died before 100 days in milk were already severely inflamed during the first few days of lactation. Dr. Baumgard thinks inflammation is the simplest and most logical explanation for why some cows don't eat well before and after calving. (31:13)
While clinical hypocalcemia (milk fever) is pathological and requires immediate intervention, is subclinical hypocalcemia detrimental to health, productivity, and profitability? (36:33)
Dr. Baumgard’s paradigm-shifting concept suggests that increased NEFA and hyperketonemia are caused by immune activation-induced hypophagia, and hypocalcemia is a consequence of immune activation. He goes on to use a high-producing, a low-producing, and a sick cow to illustrate this concept. (43:26)
In summary, the metabolic adjustments in minerals and energy during the transition period are not dysfunctional and don’t need to be “fixed.” The real fix is to prevent immune activation in the first place to prevent the cow from going off feed. Profitable production is a consequence of wellness. (52:19)
Dr. Baumgard takes a series of engaging questions from the webinar audience. Watch the full webinar at balchem.com/realscience. (56:04)
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The Balchem technical team selected abstracts of interest from the 2024 American Dairy Science Association meetings to feature on this episode of the Real Science Exchange.
Whole Cottonseed and Fatty Acid Supplementation Affect Production Responses During the Immediate Postpartum in Multiparous Dairy Cows
Guests: Jair Parales-Giron and Dr. Adam Lock, Michigan State University (0:58)
The experiment had four treatment groups: no fat supplement, 10% of the diet from whole cottonseed, a 60:30 mix of calcium salts of palmitic and oleic acid at 1.5% of the diet dry matter, and a combination of both whole cottonseed and fatty acid supplement. Energy-corrected milk was increased by almost six kilograms in cows fed the whole cottonseed diet, with a similar increase of more than five kilograms in the fatty acid-supplemented cows during the first 24 days of lactation. However, no further improvement was observed when both whole cottonseed and fatty acids were fed together. The increase in milk production was not accompanied by increased weight loss or loss of body condition.
Effect of Close-Up Metabolizable Protein Supply on Colostrum Yield, Composition, and Immunoglobulin G Concentration
Guests: Dr. Trent Westhoff and Dr. Sabine Mann, Cornell University (17:06)
In this study, cows were assigned to one of two diets 28 days before expected calving: one that provided 39 grams of metabolizable protein (MP) per pound of dry matter and one that supplied 51 grams of MP per pound of dry matter. This represents about 100% of the MP requirement and 140% of the MP requirement, respectively. Diets were formulated to supply equal amounts of methionine and lysine. Cows entering their second parity who were fed the elevated MP diet produced two liters more colostrum than second parity cows fed the control MP diet. This effect was not observed in cows entering their third or higher parity. Overall, higher MP supply did not impact colostrum quantity or quality. Dr. Westhoff also highlights an invited review he authored regarding nutritional and management factors that influence colostrum production and composition. The MP research has also been published; links to both are below.
MP paper: https://www.sciencedirect.com/science/article/pii/S0022030224010774
Invited review: https://www.sciencedirect.com/science/article/pii/S0022030224000341
Colostrum—More than Immunoglobulin G (IgG): Colostrum Components and Effects on the Calf
Guest: Dr. Sabine Mann, Cornell University (41:23)
Dr. Mann presented this abstract at an ADSA symposium titled “Colostrum: The Role It Plays In Calf Health, Development, and Future Productivity.” Her focus was to give credit to the importance of IgG while reminding the symposium audience of the importance of other colostrum components like bioactive factors and nutrients. There is potential that measuring IgG could be a marker for all the other colostrum components that have been transferred as well. We have excellent and cost-effective ways to measure IgG calf-side, but very few bioactive factors can be measured as easily. Heat treatment of colostrum to control bacterial contamination has a detrimental effect on many of the non-IgG components of colostrum. More data is needed to learn how impactful this may be to the calf. Dr. Mann details parts of the heat treatment process that farmers can check to make sure heat treatment is having as little impact as possible. She also would like to have a way to measure the antimicrobial activity of colostrum and the concentrations of insulin and IGF-1 in colostrum on-farm. Lastly, she reminds the audience that we can focus a lot on making the best quality colostrum via transition cow management and best management practices for colostrum harvest, but we still need to get it into the calf. Colostrum must get into calves cleanly and safely, at an adequate amount, and at an optimal temperature.
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series.
Shakespeare wrote, “The eyes are the windows of the soul.” Dr. Ollivett believes the lungs are the window to calf health management. The lungs are an indicator organ: respiratory disease is a symptom of management failure. Failure of passive transfer, diarrhea, septicemia, poor nutrition, a dirty environment, and heat or cold stress can all negatively impact the lungs. Often, this can manifest as subclinical pneumonia, where the lungs are abnormal but the calf externally appears completely normal. (3:51)
Dr. Ollivett reviews the defense mechanisms of the airway. When a veterinarian takes swabs to assess a respiratory disease problem, the bacteria and viruses that live in the nasopharyngeal area just ahead of the trachea are the most representative of those bacteria and viruses that are present in the lungs. The bacteria and viruses in the lower nasal passages are unreliable indicators of what is present in the lungs. (6:28)
Is coughing a good predictor of pneumonia? Research shows that if calves are coughing, it is highly likely they will test positive for a respiratory pathogen. One study showed that coughing was the best predictor of observing pneumonia on lung ultrasound, but only 37% of calves with pneumonia on ultrasound also had a cough. Dr. Ollivett observed similar results in commercial settings, where only about 10% of calves with pneumonia on ultrasound had an accompanying cough. This suggests that a cough is not a good early warning tool for pneumonia. (10:29)
Dr. Ollivett believes respiratory disease exhibits an iceberg effect, where considerably more subclinical respiratory disease exists than clinical respiratory disease. She provides examples of necropsied lungs from dairy calves to emphasize the point that calves can appear completely normal, but have the same or more damage to their lungs compared to calves exhibiting clinical signs of pneumonia. In her work, Dr. Ollivett has found that the sensitivity of lung ultrasounds to find lung lesions in animals with subclinical disease is 88%. (16:32)
What does it take to perform a lung ultrasound? Dr. Ollivett gives an overview of the process and describes what normal and affected lungs look like. Depending on the farm, 50-80% of cases can be subclinical for one to two weeks before we see signs of pneumonia. With lung ultrasounds, you can treat affected animals sooner while also getting a good assessment of where management can improve to better prevent pneumonia cases in the future. (27:37)
The prevalence of the disease is roughly equal to the incidence of the disease times the duration of the disease. Prevention of disease reduces the speed at which disease occurs, thus decreasing the incidence of disease and lowering its prevalence. On the other hand, identifying sick calves sooner should reduce the duration of the disease, also lowering its prevalence. In addition, effective treatment that reduces the duration of disease supports antimicrobial stewardship. Dr. Ollivett details criteria to evaluate treatment failure in your operation, as well as discusses antibiotic therapy in conjunction with lung ultrasounds. (34:29)
Dr. Ollivett emphasizes the impact that the gut has on the lungs on most dairy farms. She feels that as an industry, we are far too comfortable with abnormal manure in 7- to 14-day-old calves. After any abnormal manure, calves are more likely to have abnormal lungs in the next couple of weeks. Ensuring good passive transfer and maintaining a clean environment will reduce lung lesions. (50:50)
To keep calves breathing easy, Dr. Ollivett shares recommendations to reduce management failures before, at, and after birth. These can include clean and adequate space in maternity, clean calf bedding and equipment, the excellent establishment of passive transfer, adequate average daily gains in early life, and routine lung ultrasounds. (53:21)
Dr. Ollivett answers questions from the webinar audience about evaluating treatment protocols for effectiveness, technicalities and landmarks of performing lung ultrasounds, how soon after birth to begin lung ultrasounds, using lung score to determine when to treat with antibiotics, and if lung ultrasounds could be used to cull animals with lung damage before they enter the milking herd. Watch the full webinar at balchem.com/realscience. (55:44)
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Dr. Nydam and Dr. LeBlanc recently presented a Real Science Lecture series webinar on August 7, 2024. You can find the link at balchem.com/realscience.
Dr. Nydam begins with a brief overview of the concepts from the webinar, all based on understanding and applying information from different types of studies on dairy cow health and performance. Dr. LeBlanc adds that their goal was for the webinar to be useful for people with a practical interest in feeding and managing dairy cows. (4:12)
Dr. Nydam discusses different kinds of bias in research. All studies have some bias in them to some extent, so acknowledging, understanding, and trying to control for that is critical. Dr. LeBlanc describes survivor bias. In the simplest sense, survivor bias can be thought of as who’s alive to be counted. Several examples of treatments causing animals to be removed from a study or a disease-causing animal to be culled are reviewed. (8:24)
Both guests give their perspectives on p-values. A p-value tells us the likelihood that a difference we observe is due to chance. There is active discussion among statisticians about the value of the p-value. Both guests suggest that readers should also assess if the study achieved its stated objective and if there are adequate numbers and statistical power to accomplish the objective. P-values help us understand risk. A p-value does not tell us how big a difference was or how important it was. (18:54)
Dr. Nydam reviews that there are two kinds of study validity: internal and external. Internal validity centers around whether the study was done well. Was bias controlled for and acknowledged? External validity centers around the applicability of the study to the population. Is a study about mastitis treatment in water buffalo in Pakistan applicable to a dairy farm on Prince Edward Island? Peer review usually takes care of assessing internal validity. External validity is more up to each reader to decide for themself and their situation. (29:01)
Scott asks about the validity of field trial data. Both guests acknowledge the inherent challenges of field studies and give some tips for success. Field studies can often have good external validity because they are done under real-world conditions and at scale. (34:23)
The group dives into the topic of industry-funded research. Some skepticism and cynicism about industry-funded research exists. Industry-funded studies are not inherently biased and often answer important and tangible questions for decision-makers. Government funding is rarely going to be awarded to that type of research, but the industry is interested in funding it. If an industry-funded study is well done by a reputable researcher, has gone through the peer review process, and has appropriate methods and statistics, Dr. Nydam sees no reason to discount it. (44:56)
Dr. LeBlanc reminds the audience when looking at different kinds of studies and different types of evidence, it’s not that one type of study is good and others are not. For a lot of health-related research in dairy cows, we don’t have good (or any) experimental models to reproduce things in a white-coat-science sort of way. At the end of the day, dairy managers and industry professionals want to know if a particular piece of science, whether experimental or observational, helps them make decisions on the farm. There’s a place for all types of research as long as it’s done well and in its own right. (42:08)
Dr. Nydam’s key takeaway is that it’s important to remember to keep some faith in science and have open discourse about it as we move forward in dairy science and as a society. Dr. LeBlanc reminds the audience that even if listeners are not in the business of designing, conducting, and analyzing their experiments, they do not need to feel powerless as consumers of scientific information. It can and should be something they can engage with and use to answer questions in their day-to-day jobs. (52:26)
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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series.
The primary goal of a replacement program is to raise the highest quality heifer that can maximize profits when she enters the lactating herd. She carries no limitations that would detract from her ability to produce milk under the farm’s management system. Ideally, one would wish to optimize profits by obtaining the highest quality heifer at the lowest possible cost, usually in the least amount of time. Dr. Van Amburgh presents a snapshot evaluation of benchmarks to assess the potential quality of replacements. (3:47)
When does the process of creating a quality heifer start? Probably before conception. In non-pasture herds, the first lactation cows giving birth to heifers produced about 1000 pounds more milk in the first two lactations. Heifers whose dams were supplemented with choline during the pre-fresh period had higher birth-to-yearling average daily gains and improved immunity. Choline also appears to enhance the quality of colostrum via increased absorption of IgG. This implies that maternal programming extends beyond the uterine environment via ingestion of milk-borne factors, known as the lactocrine hypothesis (14:29)
After the calf is born, the goal is anabolism or growth. The dam communicates with the calf via colostrum to direct calf development after birth. Not only does colostrum provide immunoglobulins, but it also contains a large amount of nutrients and non-nutrient factors that support gut maturation. In particular, IGF-1 and insulin may act on receptors in the gut to stimulate cell proliferation, cell differentiation, and protein synthesis. Dr. Van Amburgh summarizes several studies that showed increased colostrum feeding improved pre- and post-weaning growth and development. While the immunoglobulin content of colostrum is essential for passive immunity, the other components in colostrum are responsible for the increased growth performance. (27:39)
The hormones and growth factors in colostrum enhance protein synthesis, enzyme expression, and gastrointestinal tract development. This implies that the gut is now an even stronger barrier to infection, with more surface area for digestion and absorption, with an increased capacity to digest nutrients due to higher enzyme excretion. (36:33)
To investigate the impact of non-nutrient factors in colostrum, studies were designed where calves were fed either colostrum or milk replacer with the same nutrient content. Glucose uptake was increased for colostrum calves even though both groups received similar nutrient content. Plasma glucagon was higher in colostrum calves, indicating better glucose status and higher reserve capacity. Plasma protein levels were higher in colostrum calves, suggesting more amino acids available for growth and protein synthesis. Plasma urea nitrogen was lower for colostrum calves, indicating fewer amino acids were used for gluconeogenesis leading to more efficient growth. (46:55)
What happens to immune cells in colostrum? Leukocytes and other immune-related cells in colostrum are trafficked into the circulation of the calf. Maternal leukocytes can be detected in the calf by 12 hours, peak at 24 hours, and disappear by 48 hours. Long term, there appears to be greater cellular immunity in calves that received whole colostrum compared to cell-free colostrum. Uptake of cells from colostrum enhances cellular immunity in calves by providing, mature, programmed cells from the dam. (52:24)
The take-home message for colostrum management is to feed colostrum for four days. Give first-milking colostrum within six hours of birth and again at 12 hours. Give second-milking colostrum for day two feeding and third- and fourth-milking colostrum for days three and four. (56:04)
Dr. Van Amburgh answers a few questions from the webinar audience about dry cow management for colostrum quality and quantity, the impacts of pasteurization of colostrum on components, and the efficacy of colostrum replacers. Watch the full webinar at balchem.com/realscience. (58:25)
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- Visa fler
