Автор: Travis Knutson

by Sarah Morrison, Ph.D., W.H. Miner Institute

In the first three days after calving, the milk a cow produces changes in composition as it transitions from colostrum to whole milk. This transition takes approximately six milkings after calving (or three days) for this transition to occur. Transition milk provides less concentrated nutrients and bioactives than colostrum but is still more concentrated than whole milk.

Bioactives

A bioactive is defined as a component that has biological effect. This is an umbrella term but has received quite a bit of buzz as of late. Bioactives in milk or colostrum can include proteins, fatty acids, hormones, etc. that do not necessarily directly contribute to the nutrition of the calf but can interact with the calf, either at a local level (i.e. the gastrointestinal tract) or systemically for more whole-body action once absorbed by the calf. Furthermore, the extra nutrients in colostrum and transition milk can support growth of the calf and the gut to aid in earlier development.

Feeding Study

A study from Michigan State University evaluated the effect of feeding either milk replacer, transition milk, or a 50:50 mixture of colostrum replacer and milk replacer from day 2 to 4 of life. The calves were fed two feedings of colostrum replacer for their first two feedings after birth. Then on day 2 of life, calves started being fed the treatments three times a day with 2 quarts (1.89 L) per feeding. The treatments were milk replacer [27.8% CP and 10.3% fat dry matter (DM) basis which provided 1.17 Mcal metabolizable energy (ME) per feeding], pasteurized transition milk (25.9% fat, 41.8% protein DM basis, and 1.5 g/L IgG as fed, which contained 1.44 Mcal ME per feeding), or a 50:50 mixture of milk replacer and colostrum replacer which provided 14.6% fat, 38.6% protein DM basis, 15 g/L IgG, with 1.28 Mcal of ME per feeding). The figure shows fat and protein provided by the different feeds reported in this study.

The nutrient composition and IgG measured in the transition milk before pasteurization was higher than after pasteurization. This is likely a result of the pasteurization technique used. In this study, they pasteurized the transition milk at 161°F (71.7°C) for 15 seconds, which likely denatured some of the proteins in the transition milk. Recommendations from work done by Dr. Sandra Godden would indicate best practices of heat treatment for colostrum to be 140°F (60°C) for 60 minutes because of the IgG and high solids content. At Miner Institute, we have also heat-treated transition milk following recommendations for colostrum because of the higher solids content.

After four days of age, the calves were fed and managed similarly and body weights, blood samples, and health scores were measured throughout the preweaning period.

The Results

Calves that were fed both the transition milk and the 50:50 mixture had an increased body weight of 6.6 lb (3 kg) at the end of the preweaning period compared to the milk replacer group. The calves fed only milk replacer gained 1.23 lb/d (0.56 kg/d), while calves fed the transition milk and 50:50 mixture gained 1.37 lb/d (0.62 kg/d).

The different energy density between the diets fed from day 2 through 4 accounts for some, but not all, of the difference in gain. The authors estimated that the additional nutrients consumed by calves fed the transition milk and the 50:50 mixture would account for 2.84 lb (1.29 kg) of the gain for calves fed the transition milk, and (1.26 lb) 0.57 kg for the colostrum replacer mixture. Therefore, the difference between growth among the treatments would have been residual effects after the treatments ended on day 4 of age. There were no differences in health, with overall incidence of disease very low in all groups. Colostrum and transition milk have been shown to promote the maturation of the intestine, increase absorptive capacity and digestive efficiency. Therefore, some of the difference observed from feeding transition milk or colostrum replacer could be from the other bioactives and their action on development.

We continue to learn more on this topic; however, it seems like there are beneficial effects of feeding transition milk to calves in the first couple of days after colostrum feeding. As with colostrum, it is important to feed clean transition milk that is free of contamination either through heat treatment or good hygiene techniques.

About the Author

Sarah Morrison, Ph.D. is a Research Scientist at the William H. Miner Agricultural Research Institute in Chazy, NY. Sarah grew up on her family’s dairy farm in Addison County, Vermont. She has a Bachelor’s of Science degree in Animal Science from the University of Vermont and a Master’s of Science and a Ph.D. from the University of Illinois. Her research at Miner focuses on dairy cattle nutrition and management, with a focus on calves and heifers. She can be contacted with questions at morrison@whminer.com.

Reference

Van Soest, B., F. Cullens, M. J. VandeHaar, and M. Weber Nielsen.2020.Short communication: Effects of transition milk and milk replacer supplemented with colostrum replacer on growth and health of dairy calves.J. Dairy Sci. Article in press.

by Kelly Driver

Providing the newborn calf with colostrum, ideally within the first 4 hours of life, is vital to helping it achieve passive immunity. But have we considered what to do when good quality maternal colostrum is not available? A good quality colostrum replacer can provide the healthy alternative.

Failure of passive transfer is big risk. Calves that experience failure of passive transfer (FPT) are more likely to become sick or die in the first two months of life than calves that have adequate immunity. FPT is defined as a blood IgG level less than 10 mg/mL at 24-48 hours after birth. There are many factors that can influence FPT, but the most common revolve around colostrum quality, management, and feeding. Research shows that calves should be fed a minimum of 100 g of IgG within 4 hours of birth, and feeding 150-200 g of IgG is generally recommended to assure plenty of IgG is available for the calf to absorb. (Penn State) We also know that there is a lot of variability in colostrum quality between individual cows, so all colostrum should be tested to ensure only the desired quality is being fed to newborn calves. When available colostrum is low in quality, calf managers may decide to feed either a supplement or colostrum replacer.

Is it a Supplement or Replacer? Colostrum replacers are made from either bovine colostrum or serum and contain 100-150 g of IgG per dose. These products also provide fat, protein, vitamins and minerals, but there is variance among products on the market. For example, fat content can vary widely, but a colostrum replacer will provide more immunoglobulin to the newborn than a supplement product or poor-quality colostrum. When reading the labels, you may find products labeled as “real” colostrum, meaning they contain dairy cow colostrum that has been dried down and heat-treated to eliminate harmful operatives like mycoplasma or Johne’s disease. Serum-based products are the result of blood collected to serve as the antibody source for the newborn calf. These products can transfer IgG to the calf, but can be lacking in the other maternal cells and hormones that are so vital to the newborn calf’s immune system.

There is no way of guaranteeing the effectiveness of a product unless it has been licensed by the USDA Center for Veterinary Biologics. Colostrum supplements are products that are unable to raise the blood concentration of IgG above 10 mg/mL for calves. These products may be used to increase the amount of IgG fed to calves when only lower quality colostrum is available. However, research has shown that when a supplement is added to low quality colostrum, the IgG is often absorbed poorly and FPT rates are higher as shown in the table below. This table summarizes the results of 26 different research trials published in peer-reviewed journals that used nearly 90 different treatments studying colostrum replacer and supplement products and provides a good overview of the various categories performance on average.

Be certain to read the label. Too often colostrum products are selected solely on price, but with many different products on the market, it is very important to look at the labels closely. Since IgGs are the antibodies that provide the newborn calf’s early defense against pathogens, it is important to find a product that guarantees a specific IgG level. Some products may be labeled as providing 120 grams of globulin protein, but in fact deliver less than the crucial 100 g of IgG needed for the calf’s immunity. Globulin proteins actually include other proteins along with the IgG antibodies, so the number can be misleading of the actual effectiveness of the product.

Read and follow the manufacturer’s instructions for feeding. Some products are mixed with water and others are added to existing colostrum, and the number of feedings recommended can also vary. Other products, including those packaged in bulk, offer the option of selecting the IgG dose by using different amounts of powder.

The difference in IgG dosage was studied by Godden et al., (2009a), to determine whether feeding two doses of a colostrum replacer (CR) had further benefit to IgG levels in calves and whether the benefits included all classes of IgG. Each treatment dose contained an IgG concentration of 66.7 g/L, so treatment one received 1.5L and treatment 2 was 3L by volume fed. Treatment group 3 was fed 3.8L of colostrum harvested 20-60 minutes after calving from the dam or stored refrigerated colostrum from one other cow if the dam’s colostrum was not available. All calves in the study were single births, weighing at least 70 lbs., with a calving ease score of less than or equal to 3 on a scale of 1 to 5. All calves were fed the same commercial milk-based replacer after their colostrum feeding. The results shown in the table below and underline that the 24-hour samples for serum protein and IgG in the calves did not differ between 2-dose CR and colostrum, but were greater than 1-dose CR. The apparent efficiency of absorption (AEA) was similar on all treatments, but much better rates of adequate passive transfer (APT) occurred on the 2-dose and colostrum treatments.

High quality maternal colostrum is still the best option for feeding newborn calves. However, there are times and circumstances when colostrum replacer or supplement products can be valuable tools to have available. When selecting a product to use, it is very important to understand if the product is USDA licensed, what the IgG level is, to follow mixing directions carefully, and how many doses should be fed to deliver the calf a minimum of 100 g of IgG within 4 hours of birth.

Kelly Driver has been involved in the New York dairy industry all her life. In addition to raising dairy calves and replacement heifers, she is the Northeast Territory Manager for Calf-Tel. Feel free to contact her at kellydriver@hampelcorp.com with your calf questions or suggest a topic you would like covered in a future blog.

Sources

Godden, S.M., D.M. Haines, and D. Hagman. (2009a). Improving passive transfer of immunoglobulins in calves. I: dose effect of feeding a commercial colostrum replacer. Journal of Dairy Science, 92:1750-1757.

Kertz, A.F. (2009). Calf colostrum replacer can meet IgG needs. Feedstuffs. September 14, p.12.

Lago, A., M. Socha, A. Geiger, D. Cook, N. Silva-del-Rio, C. Blanc, R. Quesnell, and C. Leonardi. (2018). Efficacy of colostrum replacer versus maternal colostrum on immunological status, health, and growth of preweaned dairy calves. Journal of Dairy Science, 101: 1344-1354.

Penn State Extension Service. (2020, April). Colostrum supplements and replacer. American Dairymen, vol. 45, no. 4: 28-32.

Priestley, D., J.H. Bittar, L. Ibarbia, C.A. Risco, and K.N. Galvao. (2013). Effect of feeding maternal colostrum or plasma-derived or colostrum-derived colostrum replacer on passive transfer of immunity, health, and performance of preweaning heifer calves. Journal of Dairy Science, 96: 3247-3256.

by Cari Reynolds, W.H. Miner Institute

As cooler weather sets in and the leaves begin to turn, we humans start to think about ‘sweater season’ and, perhaps even more importantly, ‘soup season’. The nip in the air invites thoughts of warm, hearty meals, and there are few things more inviting than a steaming bowl of soup on a chilly day. While the health benefits of a warm bowl of soup are anecdotal at best for humans (although homemade chicken noodle soup from one particular restaurant in my home region is my sworn go-to for kicking a cold), research continues to explore the impact of heat-treated colostrum on calf health. In fact, companion articles from Cornell University recently published in the Journal of Dairy Science provide new information on how heat treatment may affect other essential immunological components of colostrum and their contribution to calf development.

Colostrum management on farms is one area where cleanliness and quality are imperative. It is important to give the calf a good foundation for her immune system. High bacterial content in colostrum leads to a decrease in available immunoglobulin G (IgG), which lowers the amount available for absorption in the calf. Gut maturation and development are also supported by other complement components present in colostrum, such as growth factors, cytokines, hormones, enzymes, insulin, and insulin growth factor I (IGF-I). Many of these components and their mechanisms in colostrum have been understudied, but advancements in proteomics are allowing for further exploration of these components and their roles in immune and gut development. While it is well-documented that heat treatment reduces bacterial count and preserves IgG fractions, these two studies aimed to further explore what effects heat treatment may have on these other essential components and subsequent impact on the calf’s health and development.

First-milking colostrum from 11 Holstein cows, of which the average Brix percentage was 27%, were collected on one commercial dairy in New York State. Colostrum from each cow was collected 3x over one day post-parturition, homogenized, and divided into two 4-L (1 gallon) bags for a total of 22 paired batches. One bag was placed on ice for 30 min, then stored at 4°C (39° F) for up to 24 h. The second bag was heat treated at 60°C (140° F) for 60 min immediately after filling, placed on ice for 30 min, then stored at 4° C for up to 24 h. Samples from the raw and heat treated colostrum batches were analyzed for somatic cell count (SCC), bacterial contamination, IgG, IgA, complement components, proteins, insulin, and IGF-I. As exhibited in previous work, the heat treatment considerably improved the hygiene of the colostrum. Average SCC of the 11 raw colostrum samples was 470,000 (range 300,000-1,300,000); heat treatment reduced this count by 207,000 ± 68,000, or 36%, in comparison to their raw counterparts. Heat treatment also reduced bacterial counts by 93% in comparison to raw colostrum.

However, heat treatment reduced IgA (which is crucial to development of mucous membranes) by 8.5% when compared to raw colostrum, and reduced IgG by 6.6%. Heat treatment also decreased insulin by 22%, and IGF-I by 10.2%. A total of 328 distinct complement proteins were identified in the colostrum samples, many of which were decreased by heat treatment. While they may not be found in high concentrations, the presence of these complement components are important to the development of the neonatal immune system. The authors then sought to determine if whether or not a reduction in abundance of these components also translated to a biological impairment, or a reduction in their circulating concentrations.

Twenty-two Holstein calves were enrolled to be fed either the raw (R, n =11) or heat treated (H, n =11) colostrum at 8.5% of their body weight (0.87 and 0.91 gallons, respectively). Colostrum was placed in a 43°C (104° F) water bath for 20 min to warm to feeding temperature, and fed to calves within 1 hour of birth via an esophageal feeder. None of the calves received colostrum from their own dam. Calves were moved to a group pen (20 calves/pen) 8 h after feeding, where free-choice, heat-treated milk was offered ad libitum, and calves were treated similarly for the remainder of the preweaning period. Blood samples were collected from each calf immediately before colostrum feeding, and at 4, 8 and 24 h after feeding. Weaning weights were collected at a targeted 64 d.

Calves in both groups demonstrated successful passive transfer of antibodies, with serum IgG concentrations above 10 mg/mL. Weaning weights and average daily gain did not differ between the R and H groups, nor did the levels of serum IgA and IgG 24 h after feeding, despite the reduction of both by heat treatment. Insulin levels peaked at 4 h, but differed at 8 h as decline in insulin in group H was slower than that of group R. No differences in IGF-I were detected between groups. Insulin and IGF-I concentrations were of particular interest to the researchers due to the observed reductions in the heat-treated colostrum. 663 unique proteins were also identified in serum samples; a large number of these were noted to have changed in abundance between the 0 and 8 h timepoints, suggesting a change in the calf proteome following colostrum feeding. Of those serum proteins that were increased in abundance, 41% were also identified in the colostrum samples, and were classified as those involved in immune response and coagulation. These results suggest that many of these immunological factors are present in colostrum and help contribute to the establishment of the neonate immune system, and that lowered abundance in the heat-treated batches did not translate to diminished uptake or effect.

While more investigation of the calf proteome and the effects of heat treatment on complement components of the immune system is still necessary, this research continues to support the method of heat treatment for preservation of colostrum quality. Enhancing our understanding of these complement components and proteins, as well as their roles in development, will provide more opportunities to optimize calf health through management and nutrition strategies. Bring on the cold weather, and bring on those warm bottles!

Cari Reynolds earned a BS in Biology from the University of Scranton and a Master of Public Health from the University of Massachusetts – Amherst. After several years working in the public health sector, Cari returned to her agricultural interests and she is currently a research intern at W.H. Miner Institute. Cari is a Ph.D. student in Animal Science at the University of Vermont, where her research will focus on management and preventative strategies to mitigate diseases that impact both human and animal health. She can be reached at reynolds@whminer.com.

References

S. Mann, G. Curone, T. L. Chandler, P. Moroni, J. Cha, R. Bhawal, and S. Zhang. 2020. Heat treatment of bovine colostrum: I. Effects on bacterial and somatic cell counts, immunoglobulin, insulin, and IGF-1 concentrations, as well as the colostrum proteome. J. Dairy Sci. 103: 9368-9383.

S. Mann, G. Curone, T. L. Chandler, A. Sipka, J. Cha, R. Bhawal, and S. Zhang. 2020. Heat treatment of bovine colostrum: II. Effects on calf serum immunoglobulin, insulin, and IGF-I concentrations, and the serum proteome. J. Dairy Sci. 103: 9384-9406.

By Robert Corbett, DVM, PAS, DIPL. ACAN, Dairy Health Consultant

The most common calfhood disease that results in the highest economic loss to the dairyman is diarrhea. Dehydration and acidosis are the most important issues that have to be corrected in the majority of diarrhea cases. Most individuals responsible for treating sick calves understand the importance of rehydrating the calf and are generally familiar with the use of oral electrolyte solutions.

However, choosing which oral electrolyte to use, unfortunately, is often based on price, or the recommendation of the animal health route person that visits the calf operation. The dairy industry has been suffering from low milk prices for the past several years, so the emphasis on using less expensive products has been a high priority on most operations. It is common for the larger operations to purchase their oral electrolyte product in bulk to reduce the cost per treatment. Even though the bulk products usually contain a scoop that is supposed to deliver the exact dose needed for 1 treatment, this is often increased by a heaping scoop or perhaps more than one scoop on the premise that if a little bit is good, a lot would be better.

When choosing which product to use, it is generally assumed by those purchasing the electrolyte that they are all created equal, so price is the major factor in determining which product to buy. Another factor often considered is how well the calf will drink the oral electrolyte solution so that administering it by stomach tube will be less frequent. When looking at the labels, it is very difficult to compare one product to another. The ingredients in electrolyte are often expressed in different ways such as percentage, grams, milliequivalents per liter, etc., making it next to impossible for those who are purchasing the product to determine which product is the best as far as its ability to rehydrate the calf. In addition to this, there hasn’t been much information provided to the dairyman as far as what concentrations of the individual ingredients are optimum to rapidly restore the normal physiological state of electrolyte balance and hydration. Dr. Geoff Smith from the University of North Carolina has published several articles on this complicated topic for veterinarians, to help them better understand the physiology of rehydrating the calf and correcting acidosis, and thus be able to better advise their clients on this topic. The majority of the information on electrolyte formulation in this article is taken from a chapter written by Dr. Geoff Smith from Veterinary Clinics of North America 2008.

Diarrhea results in rapid loss of the extracellular fluid volume (ECF) with a slight increase in intracellular fluid (ICF). As stated by Dr. Smith “Sodium is the osmotic skeleton of the ECF and therefore of plasma”. Since sodium is the main determinant of the ECF, it must be included in a well-formulated electrolyte product in sufficient amounts to rapidly reestablish a normal state of hydration. There is not an exact amount of sodium that is recommended, but rather a range which was determined by the various research articles that have been published on the topic. Dr. Smith recommends that the sodium concentration be between 90 and 130 mmol/L (millimoles per liter).

Even though calves do lose some chloride with diarrhea, it is not lost in near the amounts that sodium is. Dr. Smith recommends that the chloride concentration be between 40and 80 mEq/L (milliequivalents per liter) with concentrations toward the lower end of the scale probably being better.

Potassium is also lost in the feces of calves with diarrhea. All calves with diarrhea will have a total body deficit of potassium. However, some calves with acute severe diarrhea may actually have a level of potassium that is higher than normal at the same time. When a calf becomes dehydrated, it releases a hormone called aldosterone from the pituitary gland which tries to conserve sodium and water in the kidneys, but at the expense of potassium. Dr. Smith recommends a potassium concentration of 10 to 30 mmol/L in oral electrolyte formulations.

The absorption of sodium in the small intestine is a passive process. There must be some other substance that is actively absorbed in the product in order to facilitate the absorption of sodium. The most common ingredient added to an electrolyte product to enhance sodium absorption is glucose. Glucose is also an important energy source in the diarrheic calf since most calves are in a state of negative energy balance during the episode of diarrhea. Neutral amino acids such as glycine, alanine and glutamine have been shown to increase sodium absorption. Glycine is the most common one added to oral electrolyte solutions. It is generally assumed that including both glucose and a neutral amino acid will further improve sodium absorption above that of glucose alone. Volatile fatty acids such as acetate or propionate have also been shown to enhance sodium absorption. It is also thought that adding a volatile fatty acid to the electrolyte will further enhance sodium absorption as well.

Osmalality is defined as the concentration of a solution expressed as the total number of solute particles per liter. The osmolality of the oral electrolyte solution is extremely important since it has a direct effect on how fast and complete the electrolyte solution is absorbed across the intestinal epithelium into the bloodstream of the calf. Osmalality is quite a complex subject, so only the basic information needed to determine which product would be recommended on farm will be provided. The osmolality of the various electrolyte products varies tremendously. Electrolyte products that are considered to be isotonic (the same osmolality as that of the ECF of the calf) would be in the range of 280-300 mOsm/L (milliosmoles per liter). Those that are extremely hypertonic (much more concentrated) may have an osmolality as high as 700-800 mOsm/L. If the osmolality of the electrolyte solution is significantly higher than the ECF the absorption of the electrolyte is greatly decreased, and could also result in the flow of fluids into the lumen of the intestine, causing the diarrhea to become more severe.

The main factor in determining the osmolality of an electrolyte solution is the amount of glucose in the product. The other ingredients also add to the osmolality. As mentioned previously, glucose not only enhances sodium absorption, but is an important energy source as well. The osmolality at the tip of the intestinal villus is approximately 600 mOsm/L. Therefore, the extremely hypertonic electrolyte solutions could actually result in fluid loss. Since there is already an excess secretion of fluids across the gut membrane, these extremely hypertonic solutions have the potential to increase fluid loss.

The amount of glucose in the electrolyte solution is important as an energy source, but also has a major influence on the osmolality of the product. The general recommendation is that there is between 2 and 3 grams of glucose per kg of body weight of the calf. When choosing which product to use, both the osmolality and the total amount of glucose in the electrolyte must be considered together. The extremely hypertonic electrolyte solutions often result in a slowing down of the abomasal emptying, often resulting in abomasal bloat and/or abomasitis. Dr. Smith recommends that the osmolality of an electrolyte solution be no more than 500 mOsm/L. The osmolality of the oral electrolyte solution is absolutely critical in how fast it is absorbed. For this reason, the dairyman should know what the osmolality is of the product they are using, and each company selling an oral electrolyte should know what the osmolality is. The osmolality is more important than having a high level of glucose in the product.

Almost all calves that have diarrhea will develop acidemia and metabolic acidosis. Correcting this acidosis is an important function of a well formulated oral electrolyte solution. Calves can be rehydrated but still suffer from metabolic acidosis. For this reason, it is important that an alkalinizing agent be added to the electrolyte formulation. This would include bicarbonate, acetate, and propionate. Bicarbonate is effective as an alkalinizing agent in its original state. Both acetate and propionate have to be metabolized in the liver to be effective as an alkalinizing agent. Even though this process is somewhat slower, it does not appear that there is any major difference between these two types of products as far as correcting metabolic acidosis in the calf.

Bicarbonate will lower the pH of the abomasum. If feeding whole milk, this will interfere with the normal clotting of the milk. Most milk replacers use whey protein as the protein source and these proteins do not form a clot in the abomasum, so bicarbonate will not have an effect on these types of milk replacers. Another important point is that a low pH in the abomasum is an important deterrent to bacterial pathogens such as E. coli and Salmonella. These pathogens are susceptible to a low pH and the majority of them are prevented from passing on into the small intestine if a low abomasal pH is maintained.

Acetate and propionate do not lower the abomasal pH. They also facilitate the absorption of sodium as previously mentioned. When metabolized in the liver, these volatile fatty acids are also an energy source, which bicarbonate is not. They will not interfere with the normal milk clotting process of whole milk.

Some electrolyte formulas contain Psyllium or some other gelling factor. This will slow down gastric emptying as well as absorb fluid from the intestine. However, this does not have an effect on rectifying dehydration since the fluid is still in the intestinal lumen and not in the ECF. It is generally not recommended to use these types of agents for this reason. These products will often result in less volume of diarrhea, giving the caretaker a false impression that the calf is improving, when in fact the process of improving hydration is not progressing.

Ideally, administration of oral electrolyte solutions should be spaced evenly between milk feedings to gain the maximum benefit of rehydration. This is often difficult to implement from a management aspect. Milk feedings are rarely spaced evenly apart. If feeding two times a day, it is common that the two feedings are actually spaced less than 8 hours apart so that one shift of employees can handle both feedings. This results in periods of more than 16 hours before the next morning feeding. The electrolyte feeding should be administered midway between the two milk feedings. The ideal situation would be to feed two feedings of oral electrolyte solution per day, one between the two feedings and the other after the last feeding, as far apart as possible. However, this rarely happens without having at least two shifts of employees working in the calf operation.

It is also advisable not to mix the oral electrolyte solution with milk or milk replacer. Milk products also have an osmolality, and when mixed with an oral electrolyte solution, this will increase the osmolality of the combination, likely resulting in an extremely hypertonic solution that could exacerbate the diarrhea problem. If the electrolyte solution has to be fed close to the milk feeding, it might also be advantageous to feed the milk replacer at a level of 12 to 12.5% solids.

Many dairies are feeding an increased level of solids which is beneficial for increasing growth and average daily gain. If currently feeding an increased level of solids, it would be beneficial to reduce the solids to 12 to 12.5% if it is necessary to feed the oral electrolyte solution close to the milk feeding.

There are some common mistakes that are made in the treatment of calf diarrhea. One is discontinuing the feeding of milk during treatment. The milk is the major source of nutrients for the calf and also its immune system. If treated correctly, most calves should be able to maintain a positive weight gain during a bout with diarrhea. Another is the use of oral antibiotics to treat all cases of diarrhea. In general, unless the calf has an elevated temperature, oral and systemic antibiotics are contraindicated. This will have a significant negative effect on the microbiota of the gastrointestinal tract which is important in maintaining the mucin layer of the gut lining, maintaining the gut-associated immune system, competitive inhibition of pathogens, and digestion of nutrients passing into the small intestine.

Following is a summary of the general recommendations of a well-formulated oral electrolyte solution:

• Sodium Concentration 90-130 mmol/L
• Chloride 40-80 mEq/L
• Potassium 10-30 mmol/L
• Osmalality less than 500 mOsm/L
• Strong Ion Difference at least 50 mEq/L
• Contain one or more alkalizing agents: Bicarbonate, acetate, propionate
• Glucose 2-3 grams per kg body of the calf
• Contain glucose, neutral amino acids, and volatile fatty acids to facilitate sodium absorption

In his chapter in VCNA, Dr. Smith has an excellent summary statement to veterinarians: “Practitioners should focus on selecting oral electrolytes solutions that satisfy the following four requirements: (1) supply sufficient sodium to normalize the ECF volume, (2) provide agents that facilitate absorption of sodium and water from the intestine, (3) correct the metabolic acidosis usually present in calves with diarrhea, and (4) provide energy. Additionally, the oral electrolyte should not cause any deleterious effects (such as abomasal bloat). Because veterinarians are often not directly involved with the administration of oral electrolytes to calves, it is important that they examine the electrolyte product being used in their clients’ herds and make recommendations when appropriate.”

It is important that the dairy or calf ranch is familiar with these general recommendations of the levels of ingredients in a well-formulated oral electrolyte solution so they can choose the best electrolyte product possible that is available to them. Proper administration of a high-quality product is necessary to correct dehydration and metabolic acidosis, resulting in a more rapid correction of these issues and a decreased morbidity and mortality rate in young calves. Every dairy should be able to obtain the goal <1% death loss in the milk fed calves if a good nutrition program exists along with good management, hygiene and cleanliness of the environment. This should result in a lower incidence of calfhood diarrhea as well. Implementing the proper use of a high-quality oral electrolyte solution should also be part of a well-managed calf raising operation.

Dr. Robert Corbett, DVM, PAS, DIPL. ACAN earned his B.S. and D.V.M. degrees from Washington State University. He has worked in dairy practices in Idaho, Texas and Utah, including consulting work in 13 states and several countries worldwide. He has published over 160 articles, taught over 500 seminars, and continues to consult with five major companies worldwide involved in providing supplements and additives in dairy cattle rations. This article is reprinted with permission from the March-April 2020 issue of Dairy World, published by IBA, Inc.

by James Umphrey, MS — Eastern US Udder Care & Sanitation Manager for ABS Global

In today’s profit-driven world of dairying, it is important to review all areas and find the opportunities in our operation. Where can we improve and solidify our processes that lead to a successful outcome? In the last few years, we have made unimagined advances in genetics through genomics and sexed semen, getting the best replacement heifers out of our best cows at a higher rate than ever before. High-end heifers are as valuable today as ever, but what about the offspring from the lower end of the herd? Those offspring can create opportunities to bring more value through either the use of sexed high genetic merit semen or beef semen. Either way, producers are looking at the options and making decisions right for them and their operations, then dialing in on the details critical to assuring every calf makes it to become an income stream and not a drag on the bottom line. Every calf needs to do more than survive. They must thrive.

The keys to raising healthy calves are many and complex. One key area is hygiene. To understand hygiene, we need to talk in a similar language. Often these words are used synonymously but truly mean different things:

• Cleaning: the process of removing any visible soils and organic matter including milk, saliva and feces off the surface. This is a great start to any hygiene process but not the end goal for our calf program. In cow prep procedures this is simply a dusting off or dry rub that might be performed before pre dipping the teats.
• Sanitizing: the process where we attempt to reduce the number of microorganisms in an area or on a surface that could be harmful to our health according to public health standards or requirements. Sanitizing reduces, not kills, the number and growth of bacteria, viruses, and fungi.
• Disinfecting: the process that eliminates many or all pathogenic (disease-causing) microorganisms, except bacterial spores, on inanimate objects. The goal of a pre-dip is to disinfect the udder but often falls short due to several factors.
• Sterilization: the process that destroys or eliminates all forms of microbial life (microorganisms). As an example, this is the process applied to surgical instruments in hospitals or in critical areas of an operation where even a small number of bacteria, viruses or spores can cause major issues. Sanitation and disinfection processes are not designed to kill spore formers due to the lack of efficacy of the germicide used or the time needed to kill them.

Numerous microorganisms concern calf raisers. There are also several articles available to review each of these pathogens, their mode of action, and causes of death in calves. A short review of each is below and at what age calves are typically infected.

• Cryptosporidium is a spore-forming pathogen that can affect calves around 5-35 days of age but most prevalent at 7-14 days of age. It is important to note that Cryptosporidium is not generally considered to be a “calf killer” but makes the calf’s immune system more fragile, allowing more opportunistic pathogens to get a stronghold and kill or weaken a calf beyond recovery.
• Rota virus and Coronavirus are both of major concern as they are also most prevalent at 7-14 days of age and are often associated with a calf dealing with a high Crypto load.
• E. coli is a very common pathogen in the calf rearing area and can impact any age but tends to be more devastating very early, with it being most prevalent at less than 7 days of age.
• Salmonella usually hits older calves but can vary greatly depending on the strain.

Hygiene Program for Calf Housing and Equipment

There are two major areas of concern; the pieces that you use to feed calves (buckets, bottles, nipples and mixing utensils) and the housing units. Both are key to keeping calves healthy.

The debate over whether to pressure wash or not is real and is a decision to be made based on your farm factors. My opinion is, if you can isolate the hutches or pen dividers to be pressure washed away from housing units with calves in them, there is little chance of cross-contamination. In general, pressure washing is a great idea and helps ensure that calf housing units are cleaned thoroughly. However, pressure washing can be a point source of bacterial spread to calves when completed within close proximity.

The proper process to sanitize a calf area:

Calf-Tel.com has a good SOP for the process and you can find it here:

Calf Hutch & Pen Cleaning Guide

Steps to the Goal (process)

1. The initial step is to remove the interfering agents like organic load and biofilms by cleaning the visible signs of organic matter with warm water at a temperature of 90^oF.
2. Scrub with a chlorinated alkaline detergent (CAD) at no less than 130^oF water. The CAD helps to breakdown the biofilms and fats that many organisms thrive in. The use of a CAD will also create a higher pH (11-12), which aids the destruction of certain organisms and the removal of the biofilms that can interfere and reduce the effectiveness of your germicide used to disinfect.
3. Rinse with a solution of Chlorine Dioxide (ClO2)/Acidified Sodium Chlorite (ASC) at a minimum of 50-75 ppm per research completed by Dr. Don Sockett, DVM, Ph.D. at of the University of Wisconsin. (Dairy Herd Management) We have seen excellent results at 240-250 ppm if any of the above steps are marginal.
4. Let it dry.
5. Rinse a second time with a solution of 50ppm chlorine dioxide (ClO2)/acidified sodium chlorite (ASC) less than two hours before use, allowing a minimum of one minute of contact with the equipment. This is especially important with nipples/bottles or buckets for milk.

Not all Chlorine Dioxide/Acidified Sodium Chlorites (ClO2/ASC) are the same. It is important to test your germicide regularly with an approved method for the specific product you are using. Understand the chemistry of the product you are using and that there is a verification process to ensure you have the germicidal killing power needed to achieve your calf hygiene goals. Application of ClO2/ASC can be through a drench, spraying or, in some cases, even foamed on calf contact surfaces. Some products on the market do have the ability to foam. Foaming can allow better coverage and will stay wet/active longer, increasing the effective kill of organisms.

Hygiene plays a big part in helping you maintain healthy calves and a healthy bottom line. Dairy operations often have a significant investment in genetics to get a live, healthy calf on the ground. Dialing in the details of the farm hygiene program is one important piece in the puzzle leading to that calf adding to the farm’s income statement.

James Umphrey is currently a Milk Quality Specialist and EUS Udder Care Account Manager for ABS Global Inc. He has worked in the Dairy industry for more than 35 years. Prior to ABS, James was on Faculty at the University of Florida for 18 years. He is a graduate of Auburn University receiving a B.S. in Animal Sciences and M.S. in Nutrition. At ABS he has focused on helping dairymen achieve their goals in all aspects of production and milk quality throughout the Eastern US. Please feel free to contact James at james.umphrey@genusPLC.com.

Source:

Dairy Herd Management. (2012, February). Clean calf feeding equipment in six easy steps. Retrieved from https://www.dairyherd.com/article/clean-calf-feedi…

by Kelly Driver

We all know how good it feels to snuggle into a clean, dry bed and breathe the crisp, fresh air that comes with the cooler evening temperatures as we head into the fall months. But let’s pause a bit and consider why these same things are just as important to our calves.

Proper housing provides a healthy environment for calves and includes four key elements: ventilation, comfort, isolation and economy, according to the CalfTrack^TM Calf Management Training System from The Pennsylvania State University.

Check the Thermometer

First, let’s consider ventilation. How do we know if it’s acceptable to keep calves comfortable and healthy? Here is a quick checklist:

1. Kneel in the calf’s living area to test the air about 6 inches above the bedding, where the calf’s nostrils would be as they rest.

2. Do you feel fresh air movement?

3. Do you feel any drafts? If yes, be sure to block the openings that are creating the draft during cold weather.

4. Do you notice any odors, like ammonia or a sour smell?

As we have talked about in earlier blogs, newborn calves have a narrow thermoneutral zone, being most comfortable at 55-70^oF. Because they are born with very little body fat to draw from for energy, it is vital to avoid both cold stress and heat stress for the youngest herd members. This chart from the CalfTrack^TM program is a good visual reminder that extra measures need to be taken to keep calves comfortable when temperatures inside calf housing are outside this range.

Source: CalfTrack^TM, The Pennsylvania State University

When the temperature inside naturally ventilated housing is no more than 10-15^oF warmer than the outside temperature, the system is working properly.

Making the Bed Clean and Comfortable

If the housing area selected for calves is ventilated, free of drafts and well-drained, we can begin to prepare a clean and comfortable bed for them. It is recommended to start by disinfecting the area and allowing it to dry. After the disinfectant dries, add 6-10 inches of bedding. One way to gauge this is that the calf caregiver should be able to drop to their knees on the surface without pain. Some herds sprinkle hydrated lime on the rearing area prior to applying bedding at a rate of 1 pound per 4×8 foot area. I recommend consulting with the herd veterinarian to determine if this is necessary at your facility.

Research studies have compared different types of calf bedding – wood shavings, sand, and long stem wheat straw, as related to the growth and health of dairy calves. The study revealed that the wheat straw bedding could absorb the most moisture and also provided the most insulation for heat. Calves on wheat straw bedding had the highest average daily gain and the lowest reported days of scours of the three bedding materials evaluated. (Viney)

The University of Wisconsin-Madison has studied the correlation between calf bedding and respiratory disease. A “nesting score” system was developed to compare results of different bedding volumes used. A nesting score of 3, where a majority of the calf’s legs are not visible in the bedding, resulted in a significant reduction in the prevalence of respiratory disease.

While feeding calves each day, be sure to inspect the bedding. Clean or top-dress with fresh bedding to assure that it remains dry. Keeping the bedding fresh and dry goes a long way toward keeping calves healthy, comfortable and clean. Dry, well-fed calves are also much less susceptible to the effects of cold stress as temperatures drop.

Ammonia is Bad

Ammonia gas is very harmful for a calf’s natural defense system in the trachea. Tiny hair-like fingers, or cilia, line the trachea, working to push foreign materials that the calf has inhaled up and out of the trachea. These cilia work in a wave action and serve as a defense system against respiratory infections. But this natural system can be weakened by persistent exposure to relatively low ammonia levels, allowing pathogens to enter the lungs, as the wave activity of the cilia are disrupted. This leaves calves at a higher risk for bacterial respiratory illness.

Many positive conditions exist in calf housing for the microbial activity that releases ammonia gas. Urine provides both nutrients and liquid, the bedding material often provides a favorable pH environment, and calves warm the soiled bedding when resting. (Leadley)

How do we slow down the ammonia causing bacteria? It’s as simple as clean dry bedding. Making sure calf housing areas are well drained prior to bedding is the first step. Then kneel in the bed for one minute, if your knees get wet, it is not dry enough to slow down ammonia production. Adding plenty of clean, dry bedding will serve two purposes: keeping calves clean and creating anaerobic conditions unfavorable to bacterial growth.

Does It Make Sense

Calf housing needs to make sense for the operation. Is it cost effective to build and maintain? Does it allow for timely and efficient care of the calves? Is it well-ventilated and comfortable for the calves? Is it easy to manage for the calf caregivers? As always, we suggest a discussion with both the herd veterinarian and calf care team members as any updates or changes are considered.

Kelly Driver has been involved in the New York dairy industry all her life. In addition to raising dairy calves and replacement heifers, she is the Eastern Territory Manager for Calf-Tel. Feel free to contact her at kellydriver@hampelcorp.com with your calf questions or suggest a topic you would like covered in a future blog.

Resources:

• Leadley, S. & Sojda, P. Ammonia is bad for calves. Calving Ease. April 2005. Retrieved from atticacows.com/library/newsletters/CEApril05.pdf
• The Pennsylvania State University CalfTrack^TM Calf Management Training System. Retrieved from https://extension.psu.edu/calftrack-calf-managemen…
• Viney, Kaylee. The importance of calf bedding. Retrieved from https://crystalcreeknatural.com/the-importance-of-…

by Cari Reynolds, W.H. Miner Institute

Colostrum management on farms is used to prevent the spread of disease, provide optimal nutrition to stimulate growth, and maximize passive transfer of immunity to newborn calves; this is no doubt a focus for every producer. Numerous publications and guidance exist reiterating the significance of clean, high-quality colostrum for calf health, growth, and sufficient transfer of antibodies, as well as best practices on-farm to maintain colostrum quality. This ‘liquid gold’ is influenced by more factors than one can count, including dam’s age, calving season, and even the length of dry period. While there are some factors outside of our control, how we manage colostrum prior to feeding is not, especially with regard to cleanliness. But, could we be potentially eliminating more than just harmful bacteria?

Contamination of colostrum with bacteria not only elevates the calf’s illness risk, but also considerably interferes with passive transfer of immunoglobulin G (IgG), one of the most important factors in immune development and calf survival. In addition to sanitized equipment and proper protocols for colostrum collection, many farms employ heat treatment (lower temperature, longer time) to reduce bacterial count. Several Journal of Dairy Science studies have investigated the effects of temperature and duration of heat treatment on colostrum, and have found that heating above the recommended 60°C (140°F) for 60 min can have a detrimental effect on IgG concentrations.

However, there are still concerns that heat treatments might influence colostrum quality across varying quality levels. Research from The Pennsylvania State University aimed to evaluate the effect of heat treatment times (no treatment, 30, or 60 min) on three different levels of colostrum quality (low, medium, and high) and its effect on passive transfer rates. The authors hypothesized that high quality colostrum would be more affected by heat treatment than lower quality colostrum.

First milking colostrum was pooled by quality according to colostrometer results, and then divided into 3 unique batches. The initial IgG concentrations used to dictate low, medium and high colostrum quality levels were 52.3, 65.7, and 98.1 mg/mL, respectively. Three uniform batches of each quality level were then created. Of these batches, one was frozen untreated at -20°C (-4°F), while 2 were heated to 60°C for either 30 or 60 min, cooled, and immediately frozen at -20°C. Samples from each batch were taken prior to treatment to determine bacterial content and initial IgG concentration. Calves (54 heifers and 54 bulls) were randomized to receive 1 of 9 colostrum batches, stratified by heat treatment (0, 30 and 60 min) and quality (low, medium, high), within 2 h of birth. Blood was collected from each calf prior to colostrum feeding and then 24 h after birth for serum IgG measurement and determination of successful passive transfer.

Results from this study found that colostrum IgG levels in the unheated batches were greater than in those that were heated. When compared to the unheated batches, those heated for 30 and 60 min demonstrated IgG concentration reductions of 9 and 12%, respectively. However, calves fed colostrum heated for either 30 or 60 minutes showed a 3.4 and 27.2% increase in serum IgG concentration over those fed unheated colostrum. Absorption was also improved in those calves fed colostrum heated for 60 min in comparison to 30 min. Ultimately, there was no significant change in IgG concentration with either 30 or 60 minutes of heating time, irrespective of initial colostrum quality.

Regardless of heat treatment’s impact on IgG concentrations in colostrum, there is still considerable benefit to the calf in terms of available IgG antibodies and lower bacterial counts in batches subjected to heat treatment than those that are not. The colostrum used in this study had comparably low bacterial count, so absorption rates may have been attributable to initially higher antibody availability from less bacterial interference, and less so to heat treatment. Other considerations may need to be made for colostrum with variable bacterial presence. Multiple other studies have also highlighted the improvement of passive transfer through heat treatment of colostrum. Difference in duration of heat treatment seemed to have no effect on IgG concentration, but likely still improved absorption and passive transfer rates by lowering the bacterial content of these batches. While this study was unable to positively determine the effect of heating time on colostrum quality, inferences for good colostrum management are still supported by the results. Colostrum quality should still continue to be measured when possible to ensure that IgG levels and bacterial count are within industry-recommended standards, and cleanliness should always be at the forefront from teat to tummy. So keep warming up that bottle for baby!

Cari Reynolds earned a BS in Biology from the University of Scranton and a Master of Public Health from the University of Massachusetts – Amherst. After several years working in the public health sector, Cari returned to her agricultural interests and she is currently a research intern at W.H. Miner Institute. In the fall, Cari will begin a Ph.D. program in Animal Science at the University of Vermont, where her research will focus on management and preventative strategies to mitigate diseases that impact both human and animal health. She can be reached at reynolds@whminer.com.

REFERENCES:

https://www.journalofdairyscience.org/article/S0022-0302(19)30064-5/pdf

https://www.sciencedirect.com/science/article/pii/S0749072007000758?via%3Dihub

The dairy industry has made a lot of progress in the past decade or so regarding the care and nutrition of calves. To see how far we’ve come, consider the history of milk replacer. Milk replacer was developed initially as a low-cost alternative to feeding calves whole milk, utilizing cheap fat and protein sources that were not well digested by calves. Many early formulas were very low in fat (Kertz and Loften, 2013). Eventually, formulas with 20% protein and 20% fat with feeding rates of about 0.5 kg/head/day became the norm. At this feeding rate, a 20:20 milk replacer can meet the maintenance requirements of a 50 kg calf, however there is little left for growth. As a calf gains weight, her maintenance requirements increase as well, and she would need to consume dry feed in addition to milk replacer in order to continue growing. The goal of these kinds of programs was to maximize grain intake and often wean calves early. This traditional strategy of restricting nutrients in the liquid diet is effective in keeping feed costs per day low, especially since dry feed is generally much less expensive than milk replacer.

Many producers have changed to a different strategy for raising dairy calves. Instead of trying to minimize total cost/head, they are viewing calves as an investment in the future herd. There have been several studies indicating that an increase in preweaning average daily gain (ADG) is correlated with higher milk production in the first and perhaps subsequent lactations. As a result, many veterinarians and nutritionists recommend the goal of doubling birthweight by 56 days of age, which can be achieved with an ADG of about 0.70 – 0.75 kg/day preweaning. Much of this growth comes from feeding higher amounts of milk replacer or whole milk, and therefore it is common to see feeding rates more than twice the traditional 0.5 kg/day. Along with higher feeding rates, many producers feed milk replacer with higher protein levels, often above 24% crude protein (CP) as fed. The goal with these accelerated feeding programs is to ensure early growth rates are not inhibiting future milk production.

Which strategy makes the most sense economically? It seems that the traditional strategy is to minimize costs per day, whereas the accelerated growth strategy is meant to maximize growth. Nevertheless, you’re missing out if you’re only considering costs without measuring performance or vice versa. Because calves are not yet producing milk, it’s not as easy to put a value on their performance compared to lactating cows. However, you can view each kilogram of growth as a calf’s “output.” In order to get the best value for your feeding program, you want to utilize a program that gets you the lowest cost/kilogram of gain. To calculate your feed cost/kg gain, you need to know your feed costs and your ADG.

Accelerated feeding programs often are much more expensive per day than the traditional feeding program. However, because they are designed to provide more nutrients for growth, they often cost less per kilogram of gain. With this program, you are “diluting” the maintenance costs so that your costs/kg gain are reduced. See Tables 1 and 2 to see an example of how predicted growth and cost/kg gain compare with different milk replacer feeding programs.

Table 1. Predicted growth rates according to different milk replacer programs

Table 2. Predicted milk replacer cost/kg gain according to different milk replacer programs

It’s worth noting that the predicted growth rates in Table 1. differ between the different milk replacers depending on the feeding rate. When designing a feeding program with the goal of having a low cost/kg gain, both the feeding rate and the nutrient composition of the feed must be considered. At a low feeding rate, energy is usually the limiting nutrient. Therefore, feeding a higher protein replacer like a 24:18 will not result in higher ADG compared to a 20:20 at 0.5 kg/day. Because a 24:18 is more expensive than a 20:20, your cost/kg gain will be higher with the higher protein milk replacer at the low feeding rate.

However, at a higher feeding rate like 1.0 kg/day, protein will become the limiting nutrient if you’re feeding a 20:20. For that reason, the additional protein in the 24:18 will result in higher ADG when fed at the higher feeding rate. Even though 24:18 is more expensive per kilogram, and in effect, more expensive per head per day, the additional growth you can expect from a 24:18 at a feeding rate of 1.0 kg/day will cause your cost/kg gain to be lower than it would be with the 20:20 milk replacer.

For the sake of simplicity, the above milk replacer example does not account for additional factors that will affect calf maintenance requirements. Increased bodyweight, cold environmental temperatures, and other stressors will increase energy requirements for maintenance, therefore affecting ADG. This example also did not consider starter intake. We can assume in most cases that calves will consume less starter when fed high amounts of milk replacer compared to low amounts. Each of these factors should be considered when designing a calf feeding program. You should work with your nutritionist to determine which feeds and feeding rates will work best on your farm to result in a low cost/kg gain.

The dairy industry has made great progress in the area of pre-weaned calf nutrition and growth. With so much focus on increasing preweaning ADG, many farms have adopted accelerated feeding programs resulting in larger, healthier calves at weaning. However, it seems that less focus is on the performance of calves postweaning. One of the largest challenges with feeding high rates of milk/milk replacer is that calves may not consume much starter prior to weaning. This could put them at risk for a “post wean slump,” in which calves grow more slowly or lose weight in the weeks following weaning. If this happens, it is detrimental to cost/kg gain. Unfortunately, many producers that invest a lot in growing calves quickly with an accelerated milk or milk replacer program often are at high risk for this post wean slump. It’s a good idea to not only collect calf weights at weaning, but also several weeks after weaning to identify whether calves maintain an adequate ADG.

The good news is that a post wean slump often can be avoided through good management practices. Keep in mind that change is stressful for calves, so make their transitions to new feed, groups, and facilities gradual. If you’re trying an accelerated liquid feed program, you should gradually wean calves over a minimum of 14 days. Make sure calves are eating at least 1.5 kg of starter for three consecutive days before completely weaning them, and consider continuing to feed the same starter for a week or two after weaning. Make sure feed and water are kept fresh and are easily accessible after weaning. Pay attention to all the things that are new and different to a calf in the post-weaned environment and make sure they don’t become an obstacle for eating and drinking. You may have to make modifications. For example, if calves are in a pen where they have to reach through slant bars to reach feed for the first time, you could hang a trough of feed on the inside of the pen for a few days to make sure calves can find feed easily after arriving in the new pen.

Measuring both your feed costs and your calf ADG to determine feed cost/kg gain will help you understand the efficiency of your calf program. If you don’t know your current cost/kg gain, try calculating it to see where you are today. Any time you make changes to your calf program, evaluating that number will help you decide whether those changes are worth it or not.

Alyssa Dietrich is a calf and heifer specialist with Cargill, based in Pennsylvania. She holds a B.S. in Animal Science from Penn State and M.S. in Dairy Science from Virginia Tech. She can be reached at alyssa_dietrich@cargill.com.

Sources

Kertz, A. F., and J. R. Loften. 2013. Review: a historical perspective of specific milk-replacer feeding program in the United States and effects on eventual performance of Holstein dairy calves. Prof. Anim. Sci. 29:321–332

The temperature on the thermometer is rising as spring is shifting to summer, causing calf managers to think about ways to minimize heat stress for the animals. Let’s visit about some things we might consider as ways to keep the youngest calves comfortable this season. A calf’s body will naturally attempt to maintain a constant body temperature, regardless of the temperature or weather conditions, within their thermoneutral zone; they can accomplish this without expending extra energy. Often, we think about the thermoneutral zone in conjunction with cold stress and the need for calf jackets or extra energy. However, the hot sun, climbing summer temperatures, and higher humidity can also take a calf out of its thermoneutral zone, increasing maintenance energy needs, reduced feed intakes, and lowered immune systems.

How Hot is Too Hot? When compared to cows, calves seem better able to cope with warmer temperatures. This can be attributed to their larger surface area relative to their body weight and the lower amount of heat generated compared to cows that are digesting fibrous feedstuffs and metabolizing to support high milk production levels. (Penn State) In a study completed by Gebremedhin et al., heat production by calves and water lost through evaporative cooling increased as temperatures approached 75^oF, while water lost through respiration increased when temperatures were above 68^oF. In another study, calves were exposed to treatment temperatures for seven hours and signs of heat stress were not observed until temperatures neared 90^oF with 60% relative humidity (Neuwirth et al., 1979). A 2012 study completed by Bateman et al. suggests calves may not be able to dissipate accumulated heat when daily low temperatures in calf housing exceed 77^oF. (Penn State) In all of this it is important to remember that temperature is not the sole indicator. Other factors that can influence heat stress are air movement, moisture, direct sunlight, bedding, rumination, and even hair coat.

Recognize the signs. Calves suffering from heat stress may exhibit any of these important visible signs:

• Faster breathing rate
• Open-mouthed panting
• Reduced movement
• Decreased feed intake
• Increased water consumption

Heat Stress Impacts. In a series of studies conducted by Provimi, data indicated that calves exposed to higher air temperatures (70-80^oF) had trouble dissipating heat and were unable to return to their normal body temperature during a 24-hour period. Because cattle pant and sweat to dissipate heat and this increases their maintenance energy requirement, there is less energy from the diet to advance bodyweight gains. Additionally, animals will normally experience a voluntary decrease in feed intake during times of heat stress, reducing the total energy available further. (Bateman)

Research from the University of Arizona concluded that calves in hot conditions had impaired immune systems when compared to calves living in more moderate temperatures. The study measured immunoglobulin concentrations in serum in 2- and 10-day old calves, which could cause an increase in disease for calves in hot conditions. According to Gale Bateman II of Provimi Animal Nutrition, nutritional supplements that assist in maturing the immune system may help these calves, as medium-chain fatty acids have been shown to have antimicrobial and antiviral properties. Short-chain fatty acids and linolenic acid are recognized to stimulate immune function and be anti-inflammatory. By supplementing the diet of calves in hot conditions, the number of disease-causing organisms, like cryptosporidia and rotavirus shedding, should decrease and reduce the incidence of scouring. (Bateman)

Ideas to Help Calves Beat the Heat.

Ventilation. If calves are housed in hutches, be sure to open the vents in the back or retrofit additional vents into your hutches. Calf-Tel provides a hutch vent kit that can be easily added to any style of plastic hutch. In some hot weather climates, calf managers also lift the back of the hutch 4-6 inches to provide more air movement. Some farms have had success mitigating heat stress by installing a shade cloth above the hutches. “In a Missouri study (Spain and Spiers, 1996), 80% shade cloth positioned about 3 feet above plastic hutches reduced the temperature inside the hutch by 4^oF.” (Penn State)

If calves are housed in barns or sheds, be sure the facility has plenty of air exchange and ventilation from open curtain walls, fans, or positive pressure ventilation tubes. As the summer temperatures are approaching, now is the time to clean any dust from fans and ventilation tubes to assure proper air movement. Check that all side wall curtains are working properly and that the barn ridge openings are clear of dust and debris. A few minutes of maintenance time can really assure that clean, quality air can move through the facilities as it is designed to.

Lots of clean water. Remember the 1 to 4 rules of water feeding: for each 1 pound of calf starter fed, provide at least 4 pounds (2 quarts) of water. (Leadley) Calves eating calf starter grain require plenty of clean water to efficiently ferment their feed and move their rumen contents into the other stomach compartments. In hot weather, even more water will be needed by calves to help maintain normal body temperatures. Delivering an extra feeding of cool water to any calves without access to free-choice water can really help encourage them to drink more during hot weather.

Feed good, palatable calf starter grains. During hot weather, calf starter grain containers need daily attention. The goal is to keep that fresh grain smell to encourage calves to eat more. Even small amounts of liquid, whether it is milk, water or urine, splashed in the grain can create an environment for mold and hot weather can cause the fats in grain to become rancid. (Leadley) Because calves are very sensitive to smells, keeping grain fresh is key to maintaining intake levels and keeping average daily gains levels on pace. In the hottest days of summer, it has been my experience that calves will tend to eat more during the night when the temperatures are more agreeable for them to be active and moving about. Having enough fresh water and calf starter grain available during the evening hours also will help maintain intake levels.

Bedding. Some calf raisers prefer to use inorganic bedding, such as sand, in warmer temperatures as it absorbs and then dissipates the calf’s body heat, rather than retaining it. Other producers will switch from straw bedding to dried wood shavings or sawdust as the temperatures begin to rise. Regardless of the type of bedding used, it is critical to maintain a clean, dry resting area for calves.

Work Calves in the Morning. The calf’s body temperature and the environmental temperatures are both at the lowest point for the day in the morning. This makes it the optimal time to complete any stressful activities, such as vaccinations, dehorning, and pen moves.

Kelly Driver has been involved in the New York dairy industry all her life. In addition to raising dairy calves and replacement heifers, she is the Northeast Territory Manager for Calf-Tel. Feel free to contact her at kellydriver@hampelcorp.com with your calf questions or suggest a topic you would like covered in a future blog.

Sources

• Bateman, G., II and M. Hill. 2012. How heat stress impacts the growth of dairy calves. Progressive Dairyman. 26:55-57.
• Bentley, Jennifer. (2016, July 3). Baby calves and heat stress. Dairy Herd Management. Retrieved from https://www.dairyherd.com/article/baby-calves-and-…
• Hoskins, Ann. (2019, May 17). Calf care checklist: 5 checkpoints for summer ventilation. Retrieved from https://www.vitaplus.com/blog/articles/calf-care-c…
• Leadley, Dr. Sam. (Internet). Hot weather calf care tips. Retrieved from http://atticacows.com/library/newsletters/HotWeath…
• Pennsylvania State University. (2013, June 14). Heat stress in dairy calves. Retrieved from https://extension.psu.edu/heat-stress-in-dairy-cal…