Dr. Drackley discusses, “Nutrient Requirements of Pre-Weaning Calves” during this episode of the Real Science Exchange.
Episode 141: Nutrient Requirements of Pre-Weaning Calves
Timestamps:
Dr. Drackley begins with an overview of his presentation at the 2025 Florida Ruminant Nutrition Symposium, focusing on the NASEM requirements for pre-weaned calves. He mentions some differences in energy and protein requirement calculations compared to the NRC system, as well as increased vitamin E recommendations and a more biologically based factorial approach to calculating mineral requirements. (5:59)
Dr. Overton notes that milk replacements can be formulated differently to account for changes in mineral or vitamin requirements. In herds that feed whole milk, is there any reason to think about supplementing those calves? Dr. Drackley suggests that Mother Nature may have been smarter than us all along, as the composition of whole milk matches very well with the nutrient requirements of calves. (9:43)
Dr. Lundquist asked what the impetus was for the increase in vitamin E requirements. Dr. Drackley refers to a series of studies examining the role of vitamin E in immune function that have shown the previous requirements were too low to achieve optimum health outcomes. Many dairies give a vitamin injection after birth to help boost young calves. (11:45)
The panel discusses improved colostrum feeding efforts and the variation in successful passive immunity that still exists in the industry. (13:51)
Scott asks Dr. Overton what gaps he sees in calf nutrition from his Extension specialist perspective, and he suggests that best management for weaning is still a big topic. Dr. Drackley agrees this is an area that needs some attention. He feels the industry is doing better on the baby calf side by feeding more milk, but then that almost makes weaning more difficult because people are not changing their mindset about how to step calves down from milk or what age to wean calves. (16:39)
For people feeding more milk than the traditional 1.25 lbs of solids, Dr. Drackley recommends extending weaning time to eight instead of six weeks. He also recommends at least one step down in the amount of milk, which could be a week of feeding just once a day. Calf starter formulation and quality are also critical. Research shows that providing a small amount of forage, preferably grass hay or straw, before weaning is beneficial for buffering and rumination. (18:47)
Dr. Overton asks about the research gap in our understanding of transition cow management and how that impacts the calf in utero and after birth. The panel discusses heat stress and season of birth impacts on calf growth and first lactation performance. (26:08)
The panel wraps up with their take-home messages. Discussion includes pelleted versus texturized starters, sugars in a starter to promote rumen development, the value of increasing the quality and quantity of calf nutrition, the thermoneutral zone in baby calves, and outsourcing calf raising. (33:10)
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