Transition milk

Dairy producers have long understood that providing calves with 3-5 quarts of high-quality colostrum as soon as possible after birth is critical for ensuring passive transfer of immunity and giving calves a strong start. After the first 24 hours, many producers begin feeding milk replacer or whole milk. 

However, research suggests there may be some benefits of feeding colostrum or transition milk for a longer period — even after the critical 24-hour window has passed. While calves do not absorb additional antibodies after 24 hours of age, feeding transition milk can have localized benefits within the gut, potentially reducing the incidence of illness, especially diarrhea, in calves.

What is transition milk?

Transition milk is commonly defined as the milk collected during the second through the fifth post-calving milkings. This milk is an intermediate between colostrum and whole milk. The composition of transition milk can be highly variable; in general, it contains more solids relative to whole milk. According to researchers at the University of Minnesota, milk from the second milking can contain 30% more fat, 170% more protein, 15% more calcium, 458% more vitamin A and 406% more vitamin E than whole milk.

In addition to greater nutrient content, colostrum and transition milk contain bioactive compounds, growth factors and hormones that aid in the development of the gut microbiome. For example, levels of insulin and insulin-like growth factor 1 are greatly increased in milk from the second and third milkings as compared to whole milk. These hormones play key roles in stimulating villi, mucosal and submucosal development in the small intestine, leading to better nutrient absorption in young calves.

Performance results

Recent work conducted at Michigan State University showed that feeding transition milk to calves days 2 through 4 can increase preweaning daily gains in calves. Calves were provided with colostrum and then fed 2 quarts of transition milk three times per day for nine feedings prior to receiving milk replacer on day 5 of life. These heifer calves were compared to peers fed 2 quarts of milk replacer at each feeding after the colostrum feeding. Heifers fed transition milk achieved greater weaning weights (plus 6.6 pounds on average). Additionally, both this published study as well as a follow-up study found improvements in observational health scores and blood health markers when calves were fed transition milk.

The follow-up study also showed that transition milk stimulates the development of the digestive tract through cell proliferation (increasing cell numbers), which ultimately increases small intestinal surface area and potential nutrient absorption. Calves not receiving transition milk may miss out on the opportunity for increased gut development and improved health.

Implementation strategies

If a producer is interested in feeding transition milk, they will need to weigh the benefits, feasibility and economics of implementation. The farm will need a protocol to collect the milk during the second through fifth post-calving milkings and to keep it separated from the other fresh or treated milk. The key to successful implementation will lie in how easily milkers can identify cows producing transition milk and in having an extra storage space specifically for that milk. Colored leg bands may be an effective tool to differentiate cows producing transition milk from other cows in the group. Transition milk should ideally be pasteurized to manage bacterial loads.

When collecting transition milk is not feasible, an alternative option is supplementing milk replacer with colostrum replacer. In another MSU-published study, feeding a 50:50 blend of colostrum replacer and milk replacer achieved growth and health responses like those observed when feeding transition milk. Although this approach could be more appealing from a labor standpoint, it may be difficult to justify feeding 150 grams of relatively expensive colostrum replacer per feeding on top of the milk replacer cost for three days.

Feeding an adequate amount of clean, quality colostrum within the first 24 hours of a calf’s life is the foundation for giving calves the best possible start. If it is logistically feasible to feed transition milk or supplement with colostrum replacer, producers have an opportunity to take their calves’ performance to the next level.

Barry Visser is a nutritionist for Vita Plus.