Feeding Temperature for Acidified Milk Replacer
The question I received was about the ideal temperature at which to feed acidified milk replacer to young dairy heifer calves.
The producer is set up with multiple pens. They have insulated boxes for each pen with a heater in each box for cold weather (it is a naturally-ventilated cold barn in New York State). The barrel in each box is wrapped with a thermostatically-controlled heating unit. Each box contains eight nipple feeding stations.
Fresh milk replacer is prepared twice daily and added to barrels at each pen as needed. The entire feeding system is taken apart between groups, barrel scrubbed and new tubes, check valves and nipples installed.
Now, the question. At what final temperature should the milk replacer be mixed and at what temperature should the heating units be set?
Well, it depends.
The more conservative position is to keep the acidified milk replace in the 68F to 75F (20C - 24C) range. Calves appear to self-limit meal volume at these temperatures. That is, they seem to decide they have eaten enough at somewhere between 1.5 and 2.5 quarts (1.4 - 2.4L). Supposedly the chances of indigestion are lower with smaller meals compared to larger ones assuming everything else is equal. If the farm was working with whole milk there would be a very low chance that the milk would curdle.
A more liberal position that favors higher intake levels is to keep the acidified milk replacer closer to calf body temperature (102F, 39C). Calves appear to consume larger meals when the solution is held at this temperature with slightly higher total daily intakes compared to lower-temperature feeding programs. Supposedly the chances of indigestion are higher with larger meals compared with smaller ones assuming everything else is equal.
When whole milk is used, at these temperatures I have been told that the chances of curdling are higher than when milk is held closer to 70F (21C). Neil Anderson told a story at a meeting about an acidified milk feeding demonstration at a community fair where the barrel, even though under a tent, sat in the sun and by afternoon the milk temperature went high enough to allow curdling.
Is there definitive research that compares feeding temperatures in this situation. Not that I know about at this time (June 29, 2014). Anecdotal accounts suggest good results with either temperature - thus, there are probably several variables other than meal size in the mix that predispose calves to suffer from indigestion.
Thus we go back to trying what we think is likely to work and watch the calves. They always tell us how things are going if we are willing to watch them carefully.