Researchers want to develop better industry-wide calf raising programs on farms and reduce overall morbidity and mortality rates
While colostrum is the first milk produced after calving, transition milk refers to the milk in the days after calving before it becomes whole milk. The production of colostrum by the cow ends at birth, but transition milk still contains elevated concentrations of immunoglobulins, hormones and growth factors. The concentration of these non-nutrient factors in transition milk rapidly declines over the first week after giving birth.
The importance of getting calves off to a strong, healthy start depends on getting colostrum into the calf in the first few hours after birth. The benefits of heat treating colostrum before feeding to calves and the critical timing for absorption of immunoglobulins by the calf was described in the article entitled Healthier Calves in the August 2015 Ruminations column.
Why the interest in transition milk? A few reasons have driven this focus. First, there is a desire to develop better industry-wide calf raising programs on farms and reduce overall morbidity and mortality rates. Secondly, there is a need to understand how transition milk can positively impact calf digestive tract development. Thirdly, there exists a desire to find approaches that could lead to reduced antibiotic use.
Research indicates colostrum helps activate many important developmental aspects in a calf's gut, including cell growth, increased surface area and, in particular, lactose digestion and glucose absorption.
The immunoglobulins in transition milk, even though they cannot be absorbed by calves beyond 24 hours after birth, may still create immune benefits against pathogens in the intestine. The intestine permits the large immunoglobulin molecules to be absorbed in the first few hours after birth, but it must rapidly close to create a strong barrier against pathogens that could otherwise be absorbed.
Recently, a study was done in Ireland by Muireann Conneely and colleagues that looked at the effects of feeding different volumes of colostrum and a subsequent number of transition milk feedings on immune and health status in dairy calves.
Ninety-nine calves were fed colostrum within two hours of birth. They received one of three colostrum feeding rates, based on their body weight (seven, 8.5 or 10 per cent) and then assigned to receive zero, two or four additional feedings of transition milk.
Whole milk was provided to calves not receiving transition milk or when their assigned amount of transition milk was completed. The researchers balanced the calves in the experiment based on breed (Holstein-Friesian, Jersey cross, Holstein-Friesian x Norwegian Red cross), sex and body weight.
The research used pooled colostrum and transition milk from freshly calved cows and second milk for transition milk. This was done to ensure consistency between treatments. Pooled colostrum was refrigerated and a fresh pool was created after one day. Pooled transition milk was used for up to two days and stored at ambient temperature, which averaged 6.9 degrees Celsius. Under normal farming conditions in Ontario, you would not do this since milk is a perfect breeding ground for bacteria.
Overall health status of the calves was good as determined by blood serum immunoglobulin results and health status observations done by a veterinarian who recorded health scores for nasal, eye and ear, cough and fecal score.
The blood serum immunoglobulin (IgG) results indicated at 24, 48 and 72 hours, the group fed colostrum at 8.5 per cent of bodyweight had higher serum values than both the seven per cent and 10 per cent colostrum feeding groups. It was interesting to note the 10 per cent level wasn't best, but efficiency of absorption and abomasal emptying can affect immunoglobulin uptake by the calf. Serum IgG levels peaked at 24 hours and declined at 48 and 72 hours for all groups.
The lowest IgG measures were recorded at four weeks of age, which corresponds to a vulnerable time between passive immunity acquired from colostrum fading and calf immunity increasing antibody concentration. Weaning close to eight weeks helps avoid this low point in the immune system.
The study showed some benefits of transition milk feeding, with calves fed transition milk being less likely to have a worse nasal, and eye and ear health score. The points-based health scoring system used in the study was developed at the University of Wisconsin-Madison.
In Canada, Professor Michael Steele in the Department of Agriculture, Food and Nutritional Science at the University of Alberta is starting a research project on pre-weaning intestinal development that will add to our understanding of feeding transition milk to pre-weaned calves.
Make sure your calf feeder considers the importance of transition milk feeding before switching calves over to whole milk or milk replacer feeding programs on your farm.
This article was originally published in the Milk Producer Magazine.
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