Last month we discussed the quality differences between "stockpiled" hay and "real" hay. During the winter stockpiled hay is dormant grass and, as such, requires supplementation. Real hay, if put up right, will run 8-12% crude protein; whereas dormant grass will only be about 5-6% crude protein.
Without a laboratory analysis I can tell you that cattle fed dormant grass will require supplemental protein, unless there's some legume in the mix. In most cases, you'll probably need to supplement trace minerals. A laboratory analysis will tell you for sure. Also, a lab analysis will be needed to determine if additional phosphorous will be required.
But let's put minerals aside and talk about protein since that's the most important (and expensive) nutrient. Pregnant cows grazed on dormant grass without supplementation will lose more weight than if supplemented. The weight loss, however, is not the most serious problem. The big problem is what's known as "weak calf syndrome."
Weak Calf Syndrome We've discussed weak calf syndrome before, but in light of the emphasis being put on stockpiled hay, I think it bears repeating. The bottom line is that early in her pregnancy we can shortchange a cow on energy, as long as we provide extra energy 60-90 days before parturition. Not so with protein.
Even if deficient in protein only during the first trimester of pregnancy, the fetus will be affected. Specifically, the calf will be born with a lighter birthweight. Worse yet, the calf will be weaker and have a compromised immune system. The net result will be more stillborn calves, more scours, more respiratory problems and more death loss.
Recently, there's been a lot of research on minerals and their effect on health. Certainly, minerals are important. But to a baby calf, the most important nutrient is the protein his momma gets during pregnancy. The calf is primarily made up of protein, but his momma gets first priority. Unless her needs are met, the calf will not get all he needs.
Calf Size In setting up herd nutrition programs, I'm often asked if there is anything that can be done to reduce the size of the calf ... particularly with heifers. Some producers believe that supplementing a cow or heifer will result in bigger calves. In turn, many producers believe that withholding supplement will reduce calf size and subsequent calving difficulty.
Without a doubt, withholding supplement (protein) will result in smaller calves. But, it will not make calving easier. The reason is that the cow will be weaker and any heifer will be smaller. Likewise, the calf will be weaker and will be much less likely to survive compression from a protracted delivery. The calf will also be slower to stand and consume colostrum.
The bottom line is that withholding protein is not a means of reducing dystocia. It's a recipe for disaster. If cows are forced to graze dormant grass (or stockpiled hay), they must be supplemented with protein.
David P. Price is a consulting nutritionist specializing in feedlot and range cattle. A number of his books and a subscription newsletter are available through BEEF magazine by contacting Marilyn Anderson at 800/722-5334, ext. #710.