Once-A-Day Milk Feeding for Calves:
Good Gains under Certain Conditions
A research team at Penn State University set up a milk feeding trial to compare once-a-day vs. twice-a-day milk feeding. A good colostrum management program resulting in average blood serum total protein average values of 6.0 fo calves in both feeding treatments. All calves had free-choice access to both water and calf starter grain. This was a small trial with 48 calves - 24 at 2X and 24 at 1X feeding.
On days 1-7 all the calves received two equal feedings a day for a total of 6.3 quarts (6 liters).
Starting on day 7 one-half of the calves continued on this twice-a-day feeding program.
Starting on day 7 one-half of the calves were changed to one milk feeding in the morning of 6.3 quarts.
Results? There was a small trend for 1X calves to gain a bit more than the 2X calves - that is, 3.5 pounds total gain more measured at 42 days of age.
Authors conclusion was that under these conditions [(1) fed pasteurized whole milk and (2) maximum volume of milk 6.3 quarts a day] both feeding programs were equally effective.
My conclusions are:
1. under this condition - a milk source where the protein source is primarily casein (NOT milk replacer where the protein is primarily whey protein) and milk is limited to 6.3 quarts daily - this is important because the casein curds that form in the abomasum will be slowly broken down by enzymes and released gradually into the small intestine. In comparison, directly after feeding all the whey protein floods into the small intestine - this raises the question for me about the availability of protein and energy over the 24-hour feeding period.
2. under this condition - this volume of milk (6.3 qts) is estimated for a 95lb. calf to support 1.4 pounds average daily gain under no temperature stress (60 F and higher). At moderate temperature stress (40F) this projected gain drops to 1.3 and at winter temperature stress (20F) estimated gain drops to 1.0 pounds per day. The growth-limiting nutrient here is energy, not protein.
If these calves are going to double their weight in 2 months (56 days) they need to average 1.7 pounds daily gain. Six quarts of milk, especially in cold weather, are not going to provide enough energy for this gain.
Overall, if the dairy's calf rearing goals are solely to keep the calves alive and moderately healthy through the milk feeding phase with limited growth until their rumen develops enough for them to live on a grain mix, then a once-a-day milk (not milk replacer) feeding program will work about as well as a twice-a-day feeding program under conditions of limited environmental stress.
Reference: Saldana, D. J., C. M. Jones, A.M. Gehman and A. J. Heinrichs "Effects of once- versus twice-a-day feeding of pasteurized milk supplemented with yeast-derived feed additives on growth and health in female dairy calves." Journal of Dairy Science 102:3654-3660 April 2019.