How does feeding free-choice, acidified milk replacer impact calf health and performance? Researcher Mark Hill and his colleagues at the Nurture Research Center, Provimi North America, Brookville, Ohio, evaluated the practice in a recent article in the Journal of Dairy Science.
The researchers conducted two feeding trials with Holstein bull calves from a single dairy starting at three to five days of age. Calves were housed and managed identically (in individual pens) except for their feeding programs, which were structured as follows:
Trial 1 – A 26% CP (whey protein), 17% fat milk replacer powder was reconstituted with warm water to 14% solids. For the first 35 days of the trial, 10 calves were fed two equal meals of thissolution daily at a feeding temperature of 113 to 115°F, for a total of 1.5 lb. of milk replacer per calf per day. The other 10 calves were fed the same milk replacer solution acidified with citric acid to a pH of 4.2. This liquid ration was reheated after acidification to 113 to 115°Fand offered to calves free-choice, with milk replacer consumption volume and temperature recorded five times per day. Both groups received free-choice water and identical, free-choice, 18% CP calf starter, which was weighed daily. Both groups received the non-acidified milk replacer in twice-per-day feedings on days 26, 27, 38 and 39. They were fed the same ration once per day on days 40, 41 and 42, after which they all were weaned.
Trial 2 –Forty-eight calves were fed one of four different milk-replacer treatments: (a) 1.5 pounds of as-fed powder per day in two equal meals; (b) free-choice milk replacer acidified with citric acid to a pH of 5.2 and offered for 2 hours in the morning and 2 hours in the evening; (c) acidified milk replacer offered free-choice at pH 5.2 for 24 hours per day for 35 days; and (d) acidified milk replacer offered free-choice at pH 4.2 for 24 hours per day for 35 days. After 35 days, all calves were weaned in the same manner as in Trial 1.
All calves in both trials were placed on identical post-weaning nutrition programs, and their performance was followed to 112 days of age. The researchers drew the following conclusions from the trials:
- Feeding free-choice, acidified milk replacer resulted in 0 to 7% improvement in average daily gain (ADG) in calves 0 to 4 months of age.
- Feeding temperature of the free-choice, acidified milk replacer dropped to as low as 50°F overnight.
- Intake of free-choice, acidified milk replacer was approximately 2.0 pounds of powder per day, compared to 1.5 pounds of powder per day for the control group that was fed non-acidified milk replacer twice per day.
- Overall intake was 10% lower for the 4.2 pH group compared to the 5.2 pH group on acidified milk replacer, as 10% of the calves refused to drink the 4.2 pH acidified milk replacer.
- Calf performance was similar between the calves fed acidified milk replacer for only 4 hours per day and those provided 24-hour access.
- Calves fed acidified milk replacer had similar health as calves fed non-acidified milk replacer.
- More than 95% of the free-choice milk replacer was consumed between the hours of 6:00 to 8:00 a.m. and 4:00 to 6:00 p.m.
- Behavior and feeding patterns of all calves fed all treatments was similar.
- Intake of acidified milk replacer was highly variable between calves.
The authors conclude that the results of these trials are consistent with several older published trials in which acidified milk replacer was compared to other types of milk replacer or milk. “In most U.S. market situations, the free-choice milk replacer options fed in these trials would have resulted in higher total feed costs and higher feed costs per unit of bodyweight gain compared to a fixed intake of 1.5 lb. of milk replacer per calf per day,” state the authors.