Real Science Exchange

• Florida Ruminant Nutrition Symposium: “How Beef on Dairy Selection Impacts Beef and Dairy Production with Dr. Tara Felix, Penn State University; Dr. Brad Johnson, Texas Tech University

  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)Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.  If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to [email protected]. Include your size and mailing address, and we’ll mail you a shirt. 

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• The Benefits of Mitigating Heat Stress in Dairy Cattle with Dr. Lance Baumgard, Iowa State University

  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)Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.  If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to [email protected]. Include your size and mailing address, and we’ll mail you a shirt.

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• Potential for low-forage diets to maintain milk production in forage-limited situations with Dr. Adam Lock, Michigan State University; Dr. Bill Weiss, Professor Emeritus, The Ohio State University

  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/S2666910223001084Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.  If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to [email protected]. Include your size and mailing address, and we’ll mail you a shirt.

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  48:01
• Transitioning to Success: The Intersection Between Nutrition, Health and Reproduction with Dr. Jose Santos, University of Florida

  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) Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.   If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to [email protected]. Include your size and mailing address, and we’ll mail you a shirt. 

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  1:20:13
• Legacy Series: Honoring Dr. Jim Drackley of the University of Illinois, Urbana-Champaign

  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)Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.  If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to [email protected]. Include your size and mailing address, and we’ll mail you a shirt.

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