Real Science Exchange-Dairy

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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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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Dr. Mitloehner recently presented a Real Science Lecture series webinar on September 11, 2024. You can find the link at balchem.com/realscience.

Dr. Mitloehner begins by sharing about the Clarity and Leadership for Environmental Awareness and Research (CLEAR) Center at UC Davis. He established this research and communications center to combat misinformation about sustainability in animal agriculture. One unique aspect of the center is a diverse communications department composed of journalists, filmmakers, and social media experts to help scientists communicate with the public. (6:04)

In his webinar, Dr. Mitloehner focused on animal agriculture’s impact on the climate, particularly via methane. Unlike other greenhouse gasses, methane is not only naturally produced, but it is naturally destroyed. It remains in the atmosphere for about a decade before it’s gone. Thus, if mitigation methods are used to reduce methane production, warming will also be reduced. (8:10)

Dr. Mitloehner urges continued research into improving efficiency in food production and encourages animal agriculture to take the public along with them. Stop portraying a romanticized, Old McDonald's version of animal agriculture and show what happens. There is nothing to be ashamed of, and we should be proud of the improved efficiencies and sustainability of livestock production. (13:00)

What methods or strategies exist for reducing methane? Improved ration development and feed additives to reduce enteric methane are two examples. Methane production is a heritable trait, and genomic tests are available to identify low and high methane producers. There are also ways to reduce methane loss from animal manure, including capping lagoons with anaerobic digesters to capture the gas and turn it into fuel. Dr. Mitloeher encourages voluntary, incentive-based adoption policies for these practices. (16:03)

Dr. Nichols describes her work in the Netherlands on reducing nitrogen losses. Improving protein efficiencies in livestock in the Netherlands is motivated first by environmental concerns and then by cost. Dr. Nichols expects increasing pressure in the United States regarding nitrogen load, particularly in intensively farmed portions of the country. At UC Davis, she plans to continue researching protein efficiency in dairy cows with a particular interest in optimal digestible amino acid profiles for efficient milk production.  (24:00)

Reducing crude protein in the diet decreases the amount of nitrogen excreted. As protein concentrations become more marginal, that’s when the composition of protein and amino acid in the diet becomes more critical. Dr. Nichols has found in infusion studies that the closer the digestible amino acid profile is to the essential amino acids in casein, the more efficiently dietary protein is incorporated into milk protein. (32:20)

Dr. Mitloehner gives some examples of some of the incentives available to farms in California, as well as what he sees for the future in this regard. Many of the incentives are based on improvement, which discourages early adoption and Dr. Mitloehner feels this is nonsensical. Dr. Nichols chimes in with some of the incentive-type structures in Europe. (36:21)

An additional challenge in the greenhouse gas arena is that there is no standardized protocol or measurement technique to quantify emissions. There is some effort from the United Nations and FAO to standardize some of these measures. Panelists agree that farmers are well served to document what they do and record benchmarks for things where measurements are standardized.  (44:49)

Conor’s big takeaway from this discussion is that research is ongoing to create a low emission sustainable future for animal agriculture that will take collaboration between science and policy to implement widely. Dr. Nichols reminds the audience that nitrogen should absolutely be on the minds of farmers and nutritionists, not only from an economic perspective of your ration, but also because of its environmental impact. Nitrogen mitigation is far more complicated than methane mitigation. She encourages listeners to take a look at the composition of the protein in their rations, keep good records, and see what kind of marginal changes you can make. Dr. Mitloehner encourages the audience to remember that environmental issues are intertwined with animal health and the profitability of an operation. We should not ignore emissions, we should become part of a solution. Lastly, we must find ways to effectively communicate about animal agriculture to the public. (55:31)

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