By Dr. Sam Leadley
Is there an ideal time to wean calves off of milk on to a solid-feed ration? Yes! The calf is ready when:
• the calf’s rumen is sufficiently mature to absorb the nutrients that come from digesting solid feeds and,
• she is eating enough calf starter grain to provide for maintenance and growth.
Unfortunately, looking at the outside of a calf will not reveal her level of rumen maturity. Maturity has to be estimated by observation. Specifically, keeping track of when calves begin to regularly eat calf starter grain. A practical way to do this is to only feed about one handful of grain a day starting on day two of age. Replace the grain each day. When the grain is all gone for three or more days in a row this equals “regularly eating grain.”
Most of my calves started eating calf starter grain within a three-to-five day window. To keep things simple, I just kept track of the calves that did not start eating grain in that narrow window. Since this was usually about 10% of the calves, it was fairly easy. And, as often as I could remember, I hand-fed grain to these laggards or tossed a little grain in their milk pail.
Three weeks later, assuming she continues to eat grain regularly, the papillae that line the inside of the rumen will be sufficiently mature to absorb the nutrients released from rumen fermentation. So, depending on your milk feeding program and how aggressively you coaxed calves to eat grain, somewhere around four to six weeks of age this three-week interval ends.
About this time, begin watching closely how much calf starter grain calves eat each day. When this consumption gets up to about one quart (assumes one quart of starter equals about one pound) of starter per day for several days in a row begin the weaning process. The calf’s rumen is now ready to absorb nutrients and she is eating enough grain to significantly supplement her milk ration.
If you cannot be bothered with all this detail, another approach is to start the weaning process when it most likely that all the calves are ready. You wait until eight to ten weeks. Then begin the weaning process. This method is less profitable than the “three-weeks-of-grain” method described above. I do not recommend abrupt “cold-turkey” weaning even for these calves.
How to cut back on milk/milk replacer? The most rapid increase in starter grain intake will come from reducing the milk volume. Labor savings are greatest by adopting a once-a-day feeding program. Continue feeding the same product (whole milk/milk replacer) at the same rate per feeding and drop one feeding.
This method is in contrast to the “dilution” and “gradual-cutback” methods. The dilution method keeps the volume constant and waters down either the milk or milk replacer. The gradual-cutback method keeps two feedings and reduces the volume fed at each feeding. Both of these methods work. Neither of these methods will make calves sick, nor keep them from increasing their grain intake. The point is that the once-a-day method cutting back to one-half milk volume has the advantage of driving grain intake up more quickly than the other two, as well as reducing labor costs.
The calves on once-a-day feeding will increase their time with their noses in the grain buckets. Within three to five days, grain consumption should at least double. That is, go from about 1.5 to 3 three quarts a day. Expect water intake to go up, also. Be sure they do not run out of either grain or water. In hot weather you might have to add an extra feeding of water.
During the week when I fed once-a-day it was necessary to watch grain intake carefully. If the occasional calf did not come up on grain as expected she needed to be tagged for extended milk feeding. Most farms stop feeding milk entirely five to seven days after starting the once-a-day feeding.
Many farms at this point stop milk feeding and continue free-choice starter grain feeding leaving the calves in hutch or pen housing. After one more week in individual housing the calves are moved to group pens. Some calf raisers will start adding a handful of hay in the top of the grain pail each day to condition the rumen to a forage ration. Others begin to feed a blend of starter and grower pelleted grain to shift calves to the transition pen ration.
By the way, an essential element in rumen development is feeding free-choice water. I prefer to feed warm water (80° summer, 100° cold weather) to young calves to promote higher intakes. This includes below-freezing weather when water feeding may have to be limited to once a day.