– Les Anderson and Jeff Lehmkuhler, Beef Extension Specialists, University of Kentucky
Many things in life make sense on the surface. Mark Twain once said “It ain’t what you don’t know that gets you in trouble. It’s what you know for sure that just ain’t so”. A great example is using water to put out a fire. On the surface this makes sense but if it’s a grease fire using water is a huge mistake. Beef cattle production has several examples of this but reducing feed to late gestation cows is one of the most common.
On the surface, reducing feed to late gestation cows makes some sense; less feed, potentially smaller calf, fewer calving problems, and a smaller feed bill. Fewer calving problems means more calves, more potential revenue, and, on the surface, this strategy is logical. But, like many things in life, the logical “just ain’t so”.
Fortunately, a great deal of research is available to help us understand the issues with nutrient intake of cows during the last trimester of pregnancy. As a pregnant cow moves from the second to the third trimester, her energy and protein requirements increase. Much of this increase is due to supporting the pregnancy and supporting the growth and development of the calf. However, we forget that during the last few weeks prior to calving the mammary tissues are growing and colostrum is being formed requiring energy and protein. “Uddering up” is one of those signs we watch for as cows near parturition, but we pay no attention that it took some groceries to support that udder development.
Dr. Arnold discussed some of the health-related issues of under-feeding late gestation cows last month in Off the Hoof. Here is a paragraph from her article. “New research has identified the role of “fetal programming of the immune system” during pregnancy as a major factor affecting calf vitality after birth. In fact, the latest research has proven there is no safe time during gestation to “short” a cow of her nutrient needs (including trace minerals) that will not impact the health of her unborn calf. A nutritionally deprived cow will produce poor quality and quantity of colostrum, have less energy to deliver her calf quickly, and she can lose a substantial amount of weight during her lactation so she will be slow to rebreed. Calves born to energy deficient dams will have less of the brown fat needed for energy to stand and nurse and more will die.”
Researchers have compared under-feeding and over-feeding with on-target feeding and observed the following in under-fed cows:
- Have smaller calves
- Have less energy stored in their bodies
- Have lower antibody concentrations in their colostrum and less nutrient dense milk
- Higher rates of dystocia (calving problems)
- Higher calf death loss
- Take longer to resume estrous cycles
- Have lower pregnancy rates in the following breeding season
To clinch the nail on feeding late gestation cows, Dr. Steve Loerch and coworkers at The Ohio State University went to the extreme and examined the impact of type of feed on calving and reproductive performance. They fed cows either a normal forage-based ration or a ground corn-based diet with both diets balanced to meet the cow’s nutrients needs. Cows fed strictly corn-based diet had larger calves by 5-6 pounds, but the dystocia rate was not impacted. Pregnancy rate and calf weaning weight tended to be higher in the cows fed the corn-based diets. These data illustrate that even feeding extreme diets, dystocia rate and calving problems are not impacted by late-gestation feeding.
Even if you are not intentionally restricting nutrient intake, you may be unintentionally. We know that a higher plane of nutrition can slightly increase birth weight, but we also know that feed intake drops prior to calving in cows. Combine this reduced intake prior to calving with feeding a hay that just meets maintenance needs of a dry, mid-gestational cow all the way through to calving, and you have unintentionally got her nutrient balance out of whack. Nutrient balance issues lead to losing body weight, more dead calves, and lower reproductive rates.
Forty+ years of data very clearly indicate that the logic of reducing feed to cows before calving is not a sound management plan. Calving performance, calf death rates, calf health, calf weaning weights are all negatively impacted by underfeeding cows before they calve. Saving that feed on late gestation cows is like throwing water on a grease fire . . . it just doesn’t work.