Feeding hay to young dairy calves is widely practiced throughout Virginia and the U.S.
Dairy Pipeline: March 1996
Tom L. Bailey
Dairy Production Medicine
Virginia-Maryland Regional College of Veterinary Medicine
In fact, a recent survey of calf management indicates that 88% of producers provide forage to young nursing calves. Of importance to note, is the nursing calf derives energy and amino acids from intestinal digestion of milk. However, after weaning most energy is derived from ruminal fermentation of dietary carbohydrates and amino acids from a combination of bacterial, protozoal, and dietary proteins. This change in nutrient source is primarily due to ruminal development, and is initiated by volatile fatty acids production, in particular butyrate. Dry feed (calf starter and hay) is the primary substance for production of volatile fatty acids. However, hay does not contribute to the production of butyrate or the initiation of ruminal development (Quigley, University of Tennessee). The primary end-product of hay or other roughages is acetate, which does not stimulate rumen growth and development. Grains, on the other hand, have as their primary end-product butyrate. Therefore, it is the consumption of grains that has a greater role in the stimulation of ruminal development and function. Because a calf can only consume so much dry matter, the addition of hay to the calf's ration greatly decreases the intake of grain, leading to a decrease in energy level from the total ration and a delay in ruminal function. Energy requirements in calves are great, and the need to develop a functional rumen is a priority, therefore the addition of forage should begin only after the calf has reached 12 weeks of age.