Real Science Exchange

This episode of the Real Science Exchange podcast was recorded during a webinar from Balchem’s Real Science Lecture Series.

Dr. Goff sees three main challenges for transition cows: negative energy and protein balance, immune suppression, and hypocalcemia. About half of all older cows experience hypocalcemia, and around 3% will experience milk fever. Cows develop hypocalcemia if they are unable to replace the calcium lost in milk from either their bone or diet. Compared to the day before calving, a cow needs around 32 extra grams of protein the day of calving to meet her increased requirements. (2:00)

Dr. Goff reviews the pathways of calcium homeostasis and the actions of parathyroid hormone (PTH). Aged cows may have a harder time maintaining calcium homeostasis due to the loss of vitamin D receptors in the intestine with age and fewer sites of active bone resorption capable of responding quickly to PTH once they have finished growing. Blood pH plays a role in calcium homeostasis: when blood pH becomes alkaline, animals become less responsive to PTH. Dr. Goff reviews the impacts of high vs low DCAD diets and reviews the amount of time it takes for the kidney and bone to respond to PTH. (4:20)

There are several strategies to reduce the risk of hypocalcemia. One is to reduce dietary potassium so the cow is not as alkaline. Using forages from fields that have not had manure applied to them is one way to accomplish this. In addition, warm-season grasses (corn) accumulate less potassium than cool-season grasses, and all grasses contain less potassium as they mature (straw). A second strategy is to add anions such as chloride or sulfate to the diet to acidify the blood to improve bone and kidney response to PTH. Research has shown that sulfate salts acidify about 60% as well as chloride salts. The palatability of anionic diets has led to commercial products such as Soychlor. (13:06)

Dr. Goff then discusses the over- and under-acidification of diets and gives his opinion on the appropriate range of urine pH for proper DCAD diet management, including a new proposed DCAD equation to account for alkalizing and acidifying components of the diet. He also gives some options for pH test strips to use for urine pH data collection. (18:30)

Dr. Goff’s lab has found that as prepartum urine pH increases, the calcium nadir decreases. The inflection point is right around pH 7.5, where above 7.5 indicates a higher risk of hypocalcemia. Data from other researchers suggests that urine pH lower than 6.0 may result in lower blood calcium, indicating an overall curvilinear response. Low urine pH (under 6.0) has also been associated with a higher incidence of left-displaced abomasum. (29:02)

Moving on to other minerals, Dr. Goff discusses phosphate homeostasis and how that interacts with calcium in the close-up cow. Feeding too much phosphorus can decrease calcium absorption and feeding low phosphorus diets before calving can improve blood levels of calcium. He recommends less than 0.35% phosphorus in close-up cow diets. For magnesium,he recommends 0.4% prepartum and immediately postpartum to take advantage of passive absorption across the rumen wall. (31:08)

Another strategy to reduce milk fever risk is to reduce dietary calcium prior to calving to stimulate parathyroid hormone release well before calving. A zeolite product that binds calcium is now available and may make this much easier to achieve. (42:59)

In closing, Dr. Goff reminds the audience that some level of hypocalcemia post-calving is normal and in fact, is associated with higher milk production. The key is making sure that the cow’s blood calcium levels can bounce back to normal by day two after calving. (51:23)

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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.

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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This Real Science Exchange podcast episode was recorded during a webinar from Balchem’s Real Science Lecture Series. You can find it at balchem.com/realscience.

How can we increase milk protein and capture that income opportunity? Dr. Van Amburgh describes the seasonal drop in milk protein observed in the summer months. Heat stress may play a role in altering insulin sensitivity and how the cow partitions nutrients. What can we do to avoid that seasonal decline in milk protein? (0:01)

Simple things like cooling, fans, and sprinklers can reduce heat stress and increase cow comfort. Dr. Van Amburgh recommends promoting dry matter intake and lying time, with feed available 21-22 hours per day and more than 12 hours of lying time per day. (5:27)

Dr. Van Amburgh discusses basic formulation considerations for amino acid balancing including current feed chemical analyses that include NDF digestibility, characterizing the cows appropriately by using accurate body weights, understanding DMI and making sure actual milk lines up with ME and MP allowable milk, assessing body condition changes, and understanding the first limiting nutrient of milk production. Areas where mistakes are often made include using much lighter body weights than actual to formulate rations, not using actual DMI, and using feed library values instead of actual feed chemistry. (8:00)

Milk protein percentage and dietary energy are closely aligned. This is often attributed to ruminal fermentation and microbial yield. Sugars, starches, and digestible fiber sources drive microbial yield. While protein and energy metabolism are considered to be separate, that is an artificial divide and they should be considered together. Once adequate energy for protein synthesis is available, providing more dietary protein or amino acids can increase protein synthesis further. Dr. Van Amburgh provides some ranges of target fermentable non-structural carbohydrates, starch, sugar and soluble fiber appropriate for early peak and mid-lactation cows. He speaks about the benefits of adding sugars to the diet instead of trying to continue to increase starch. (11:15)

Dr. Van Amburgh details an experiment using more byproduct feeds in a lactation diet to successfully increase intake and subsequently, milk protein content. (24:04)

Milk protein increases with higher DCAD in diets, independent of protein level. Increasing DCAD can also lead to increased DMI, probably through better fiber digestion. The mechanism is not completely understood, but perhaps some rumen microbes have a higher requirement for potassium. In another study, feeding higher DCAD resulted in an 11% increase in milk protein yield and a 26% increase in milk fat yield. (32:39)

Feeding fatty acids may also improve milk protein via insulin signaling pathways. A 5.6% increase in milk protein was observed when the ratio of palmitic acid to oleic acid was around 1.5:1. (36:21)

Dr. Van Amburgh encourages the audience to pay close attention to digestibility of dietary ingredients and shares an analysis of ten different sources of feather meal that varied in digestibility from around 50% up to 75%. (40:10)

Dr. Van Amburgh details an experiment targeting optimum methionine and lysine levels for improved milk protein. In an example with 60 Mcals of ME in the diet, the targets were 71 grams of methionine and 193 grams of lysine. (42:00)

Questions from the webinar audience were addressed. They included information about the best type of sugars to add to diets, if protozoa are preferentially retained in the rumen, BMR vs conventional corn silage, amino acid supply when dietary crude protein is around 14-15%, using metabolizable energy instead of net energy, variability of animal protein blends, and methionine to lysine ratios. (48:23)

To end this podcast, Dr. Jose Santos steps in to invite everyone to the Florida Ruminant Nutrition Symposium in Gainesville held February 24-26.

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In times of limited forage, dairy producers may need to feed diets lower in forage than is typical but would like to maintain milk production. In this study, two diets similar in neutral detergent fiber (NDF), starch, and crude protein with different amounts of forage were fed to 32 mid-lactation Holstein cows in a crossover design. The control diet (CON) contained high forage (55.5% of diet dry matter) with no supplemental fatty acids or amino acids. The low-forage diet (LF) contained 36.6% forage along with supplemental fat and rumen-protected methionine and lysine. As forage was removed from the LF diet, it was replaced with byproducts and high-moisture corn was replaced with dry corn. (4:42)

Dr. Lock added fat and amino acid supplements to the LF diet to not lose milk production. The fat supplement was a palmitic-acid-rich prill. Dr. Lock does not think the response would have been the same if a different fat supplement had been used. The LF diet was higher in fat and palmitic acid, but most other fatty acids were fairly similar between the two diets. (16:25)

Milk yields were similar between the two diets. Cows on the LF diet consumed about 1 kg more dry matter each day than CON-fed cows. Cows fed the LF diet also had higher milk fat and milk protein yields and content which led to an approximately 2 kg increase in energy-corrected milk compared to cows fed the CON diet. Dr. Lock believes the fat and amino acid supplementation were a key part of achieving these results, and they would not have seen the same response if those supplements had not been added to the LF diet. The LF diet spared around 5.5-6 kg of forage per day, and cows gained body condition. (22:03)

Dr. Weiss asks Dr. Lock to speculate if low-forage diets fed for longer periods would have negative health impacts. Dr. Lock feels that usually production would be negatively impacted by cow health issues, which was not the case here. However, if high-moisture corn had been used in the LF diet, he predicts they would have seen negative impacts. (27:18)

What about low-forage diets for early lactation cows? Dr. Lock suggests looking at diets in other parts of the world where forage is limited and see how dairy producers manage diets in those instances. He speculates that lower forage could be successfully implemented in early lactation cows after the fresh period. (31:09)

Dr. Weiss and Dr. Lock discuss the apparent improved digestibility of the LF diet given the increased production. While byproduct ingredients are often more fermentable in vitro, the results don’t always translate in vivo. Palmitic acid supplementation has been shown to improve fiber digestibility, so that may have happened in this experiment. (32:12)

On the protein side, we’ve moved away from talking about crude protein in the diet and toward amino acid concentrations. Dr. Lock would like to see the same trend in the industry for fat in the diet. A good leap was made recently from ether extract to total fatty acids, and he hopes to see individual fatty acids as the next step in that evolution. He recommends two questions be asked when considering a new fatty acid supplement. What is the fatty acid profile? What is the total fat content? The appropriate fatty acid profile is going to depend on the basal diet and what type of cow is being fed. Dr. Lock’s preference is a palmitic: oleic acid blend around 70:20 or 60:30 early in lactation, with a higher palmitic blend later in lactation. He expects the current work with different oilseeds to provide some good recommendations for feed ingredients to incorporate to increase dietary fat. (35:53)

As genetics continue to improve and nutrient requirements of cows continue to increase, is it conceivable that someday we are going to purposefully decrease fiber in the diet? While that may be the case, Dr. Lock reminds listeners that about half of milk fat comes from acetate and butyrate produced in the rumen, so fiber is still going to be critical. While we may lower the forage in a diet, forage quality is going to remain very important. (39:45)

The panel wraps up with their take-home messages from this paper. Clay looks forward to more research with a factorial design to further evaluate low-forage diets. Dr. Weiss reminds listeners there’s no one recipe for diets to achieve high yields of milk components. Lastly, Dr. Lock is excited about the future of research in this area and refining diet formulation in the area of fat supplementation. (43:21)

You can find this episode’s journal club paper from JDS Communications here: https://www.sciencedirect.com/science/article/pii/S2666910223001084

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