Real Science Exchange

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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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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Dr. Arshad begins by reviewing the inclusion criteria in the meta-analysis he conducted. He wished only to look at studies where lysine was supplemented in a rumen-protected form. The meta-analysis did not include studies that infused lysine into the abomasum or intestine. In addition, only completely randomized design or randomized complete block design studies were included. Feed ingredients and chemical composition of diets for each experiment were run through NASEM to predict the metabolizable lysine content using the same model so all studies were on the same scale. (6:04)

The bioavailability of the different rumen-protected lysine products used in the studies ranged from 22 to 90 percent. If the paper's authors reported bioavailability values, they were used in the meta-analysis. If the paper did not provide bioavailability values, Dr. Arshad contacted authors or lysine product manufacturers to offer them. (13:53)

Dr. Arshad discusses the percentage of lysine as a percent of metabolizable protein in the diets as well as differences among the prediction of the flow of amino acids to the small intestine from NASEM, NRC, and CNCPS models. (16:45)

Around 40% of the meta-analysis dataset was from early lactation cows where rumen-protected lysine was supplemented starting from 20 days in milk. The rest of the dataset came from mid-lactation cows. The duration of lysine supplementation also varied. Cows supplemented with rumen-protected lysine for more than 70 days In early lactation produced 1.5 kilograms more milk than control cows. Mid-lactation cows supplemented for less than 70 days produced 0.8 kilograms more milk than control cows. Increasing lysine as a percentage of metabolizable protein linearly increased milk and component yield. (20:11)

During the transition period, cows not only experience negative energy balance but also negative protein balance, estimated at one kilogram of protein loss from skeletal muscle during that time. Plasma lysine starts to decrease around 21 days before calving but bounces back after seven days in milk. This suggests that lysine utilization by the mammary gland and other tissues is high during the prepartum period. Supplementing lysine before calving and during early lactation should improve the efficiency of protein synthesis and may explain the difference between early and mid-lactation responses observed in the meta-analysis. (24:10)

Lysine supplementation improved feed efficiency. Dr. Arshad discusses potential reasons for this and also points out that somatic cell counts were lower for lysine-supplemented cows, suggesting that this amino acid may be important for mammary gland health. He also discusses some of the interactions with methionine found in the meta-analysis. Dr. Zimmerman and Dr. Arshad also hypothesize about the mechanism of action of supplemental lysine increasing milk fat percentage. (30:44)

Dr. Arshad describes how he would design the next rumen-protected lysine study given what he learned from the different studies in the meta-analysis. In particular, he would like to see more work with primiparous cows, and dose-titration studies to pinpoint the optimal amount of lysine to supplement and to further explore the impact of lysine on immune function. (42:42)

The base diet and bioavailability of the rumen-protected lysine product are critical components to determine the supplementation rate for a particular group of cows. Dr. Arshad details the differences between this meta-analysis and previous meta-analyses regarding lysine supplementation. (46:40) 

In closing, Dr. Zimmerman was excited to see this meta-analysis and it validated observations from the field. Dr. Weiss underlines the strict inclusion criteria and regression analysis as particularly strong points in the paper. Finally, Dr. Arshad reminds the audience that creating a balanced ration should include essential and non-essential amino acids. He again emphasizes the importance of having an understanding of the bioavailability of rumen-protected products before conducting research projects with them. Lastly, he identifies a research gap regarding lysine supplementation of primiparous cows, which make up 30-35% of herd dynamics. (52:43)

You can find this episode’s journal club paper from the Journal of Dairy Science here: https://www.journalofdairyscience.org/article/S0022-0302(24)00499-5/fulltext

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Choline was discovered in 1862 in pig and ox bile (“chole” in Greek). It is a simple nutrient containing five carbons and a nitrogen. Choline is considered a quasi-vitamin since its requirements and de novo synthesis are both higher than the B vitamins it’s similar to. Pigs can synthesize more choline than chickens. Choline is considered to be a conditionally essential nutrient depending on the physiological stage and choline production ability of the species being considered. (3:29)

Choline is involved in cellular maintenance and growth at all life stages. In particular, it’s involved in neurotransmission as a component of both sphingomyelin and acetylcholine. Phosphatidylcholine is a major component of cellular and organelle membranes and is involved in lipoprotein synthesis for the transport of lipids. Choline is converted to betaine upon oxidation, and betaine plays an important role in one-carbon metabolism as a methyl group donor. (8:43)

Dietary-free choline is preferentially used for acetylcholine and phosphatidylcholine synthesis. Phosphatidylcholine is the most abundant form of choline in the body. In general, water-soluble forms of choline are absorbed faster and have a higher tissue incorporation rate than lipid-soluble forms. (14:58)

 

Clinical signs of choline deficiency include reduced growth and reproductive performance. In pigs and chickens, choline-deficient diets lead to lipid accumulation in the liver. In broiler chickens, perosis is a classic choline deficiency sign and may progress to slipped tendons. From human studies, we know that insufficient methylation capacity during early development increases the risk of neural tube defects and impaired cognitive function. (16:44)

As animals age, their dietary source of choline transitions from water-soluble forms to lipid-soluble forms. Mammalian young receive water-soluble choline from milk, and avian species from the egg yolk. After weaning in pigs and at the hatch in chickens, the dietary choline source transitions to lipid-soluble forms found in oilseed meals. Dr. Dilger goes on to describe choline concentrations in common feedstuffs and supplements. Feedstuff type and processing methods have a profound influence on bioavailable choline content. (19:16)

Dr. Dilger details some of his work with choline and betaine in poultry diets. The requirement for preformed choline is relatively high for poultry because they lack capacity in a particular methyl transferase enzyme responsible for de novo synthesis. They also have relatively high choline oxidase activity which favors the formation of betaine from choline. Betaine is critical as a buffer to counteract the toxic effects of uric acid in the avian kidney. Dr. Dilger describes choline dietary requirements for avian species. (27:38)

Pigs have more efficient methyl transferase activity for de novo synthesis of choline. Sufficient choline is provided by milk and practical diets. For growing pigs consuming corn-soybean meal diets where methionine can completely spare choline, there is little benefit of choline supplementation for growth. Choline requirements increase for gestating and lactating sows. Swine requirements for choline were set in the 1940s and 1950s. Dr. Dilger believes these requirements need a second look given the great changes in pig and crop genetics since the requirements were originally established. To that end, work in his lab has shown that choline intake during gestation and lactation influences sow milk composition, body choline concentrations and forms, metabolomic profiles and brain development of pigs. (35:18)

In conclusion, Dr. Dilger considers choline a pervasive nutrient due to its crucial metabolic roles. Species-specific idiosyncrasies drive choline requirements, and analytical data for choline-related compounds is lacking. Different forms of choline have different metabolic kinetics and the potential for choline deficiency remains a practical issue. (46:15)

In closing, Dr. Dilger answers an extensive set of questions from the audience. Watch the full webinar at balchem.com/realscience. (48:32)

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Dr. Kononoff’s lab evaluated retrospective feed mixing records collected from eight commercial dairy farms. Data was divided into 28-day periods. Daily TMR nutrient deviation was automatically calculated from feed mixer data as the actual amount of a nutrient fed minus the target amount from the original diet formulation, divided by the target amount. (5:43)

Crude protein, NDF, fat, and starch were the nutrients evaluated in the study. (13:40)

Variation was positive for every nutrient on the vast majority of days. Dr. Kononoff attributes that to more feed being delivered than the diet formulation predicted animals would consume. Dry matter intake decreased with increasing positive deviation days in starch and increased with increasing positive deviation days in crude protein. NDF deviation did not impact dry matter intake. A narrow range of diets was used in the dataset and the main byproduct feed was high in NDF, so Dr. Kononoff speculates that there was not a wide enough range in NDF to have an impact on intakes. (17:04)

Milk yield increased with increased positive deviation days in starch and decreased with increased positive deviation days in NDF. The pregnancy rate increased with increasing positive deviation days in fat and decreased with increasing positive deviation days in crude protein. Unfortunately, milk urea nitrogen data was not available in the dataset to further investigate the crude protein/pregnancy rate relationship. (20:44)

There was little farm-to-farm variation in the data. (25:08)

As positive deviation days for starch increased, so did feed conversion. The opposite effect was noted for NDF. As positive deviation days for fat increased, feed conversion decreased. This result was a little surprising, as delivering more energy usually improves feed conversion. However, the dataset did not specify the source of fat or fatty acid profile, so there may have been some rumen fermentation interference from fat. (27:08)

Dr. Kononoff thinks it would be interesting to track individual cows through lactation and collect nutrient variation data. Dr. Weiss asks if the correlation between daily farm milk yield and nutrient variation was evaluated; it was not. Dr. Kononoff agrees that there may be some additional correlations that would be interesting to run. (33:22)

In closing, Dr. Zimmerman commends Dr. Kononoff’s work in tackling such a large dataset and looks forward to follow-up research. Dr. Weiss agrees and encourages more data extraction from the dataset. He was also very surprised at the low farm-to-farm variation observed and speculated if that would hold up if there were more variation in diets. Dr. Kononoff reminds the audience that taking a look at the TMR beyond the paper ration and digging into mixing techniques and TMR consistency is as important as evaluating bulk tank information or the amount of milk shipped. (37:20)

You can find this episode’s journal club paper from the Journal of Dairy Science Communications here: https://www.sciencedirect.com/science/article/pii/S2666910224000760

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Balchem sponsored several abstracts presented at the 2024 ADSA Annual Meeting. This episode consists of five segments, each focused on an abstract.

Segment 1: Evaluating the total mixed ration stability of rumen-protected lysine products.

Guests: Kari Estes, Balchem; Dr. Mark Hanigan, Virginia Tech

This research compared the TMR stability of a Balchem prototype, several commercially available rumen-protected lysine products and a positive control of unprotected lysine. (3:39)

A sample of TMR and the equivalent of one gram of lysine from each product were mixed and placed in a  plastic zip bag for 0, 6, 12, or 24 hours. After each time point, the sample was placed in a strainer bag, dipped in distilled water, and drip-dried. The solution was collected and analyzed for free lysine content. (5:28)

About 85% of the unprotected lysine was recovered at 0 hours. After 24 hours, around 50% was recovered. The rumen-protected lysine products varied widely; one product released nearly 87% of its lysine in 24 hours, while another only released 9%. TMR stability should be taken into account when determining feeding rates and handling of rumen-protected lysine products. (7:19)

Segment 2: Evaluating the total mixed ration stability of rumen-protected choline products.

Guests: Kari Estes, Balchem; Dr. Mark Hanigan, Virginia Tech

In this experiment, Kari evaluated TMR stability of five commercially available rumen-protected choline products, along with a positive control treatment of unprotected choline chloride. (14:04)

At 0 hours, about 80% of the unprotected choline was recovered and 50% was recovered at 24 hours. Results for the rumen-protected choline products were highly variable, ranging from 5% release to 100% release at 24 hours. Rumen-protected choline products should be evaluated for TMR stability in addition to rumen stability and intestinal release. (17:25)

Segment 3: Effect of dry period heat stress and rumen-protected choline on productivity of Holstein cows. 

Guests: Maria Torres de Barri and Dr. Geoff Dahl, University of Florida

The experiment had four treatments: heat stress with and without rumen-protected choline, and cooling with and without rumen-protected choline. Cows in the cooling treatment were provided shade, soakers, and fans, while cows in the heat stress treatment were only provided shade. (24:45)

Heat-stress cows had higher rectal temperatures and respiration rates than cooled cows. Heat-stress cows also had lower dry matter intakes, shorter gestation length, lighter calves, and produced less milk. (29:36)

For cows in the cooling group, choline supplementation increased milk production. However, cows in the heat stress group supplemented with choline produced less milk than cows who did not receive choline. (31:04)

Dr. Dahl suggests that not cooling cows in heat-stress environments when they’re receiving choline will not result in optimal results. (33:49)

Segment 4: Effects of dietary rumen-protected, ruminal-infused, or abomasal-infused choline chloride on milk, urine, and fecal choline and choline metabolite yields in lactating cows. 

Guests: Mingyang (Charlie) You and Dr. Joe McFadden, Cornell University

This experiment evaluated early and late lactation cows supplemented with choline via three different methods. Each treatment had 12.5 grams of choline ion provided daily: fed in rumen-protected form, continuously infused into the rumen, or continuously infused into the abomasum. (36:29)

Choline bioavailability was influenced by the delivery method of choline. Fecal and milk choline concentration was only observed in early lactating cows with abomasal infusion. Abomasal infusion increases the choline metabolite betaine in feces and urine. These results suggest there is potential saturation of choline metabolism in the lactating cow. (40:53)

Segment 5: The metabolic fate of deuterium-labeled choline in gestating and lactating Holstein dairy cows. 

Guests: Dr. Tanya France, University of Wisconsin; Dr. Joe McFadden, Cornell University

Dr. France explains that choline can be metabolized via two different pathways. Using deuterium-labeled choline (D-9 choline) allows researchers to know which pathway is used. If D-3 or D-6 choline is measured, the methionine cycle is used, and if D-9 choline is measured, the CDP choline pathway is used. The hypothesis was that the physiological stage (late gestation vs early lactation) would influence choline metabolism. (51:06)

Dr. France found that both choline metabolism pathways were used in both physiological stages. This experiment also confirmed that choline is a methyl donor and that choline recycling can occur. The research also evaluated the relative amounts of choline and choline metabolites in each pool. (53:40)

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