Early weaning provides boost for young, thin cows

News
Sep 11, 2009
by WLJ
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Early weaning provides boost for young, thin cows

The common tradition for weaning spring-born calves is to wait until late October and even early November. Most mature cows that have been feeding on adequate summer forages will be in very good body condition, despite the pressure of nursing a rapidly growing calf. These cows will usually be in a body condition score of about 5 to 6 at weaning time each fall. However, very often, 2-year-old cows and even some 3-year-old cows will be in marginal body condition at the end of summer. They have a nutrient requirement for continued growth and in the case of the 2-year-old, they are replacing baby teeth with adult teeth and are not as effective at harvesting forage. Therefore, many of these young cows go into the fall season in a body condition score of 4 to 5 or less.

If the rancher chooses to wait until late October to wean the calves from these marginal young cows, there is very little time between weaning and the first killing frost. This is a time when a young cow could recover considerable body condition if she has access to a plentiful supply of late summer, warm season grass. Without the nutrient drain of producing and delivering milk, she can use this pre-frost period to great advantage and replenish her own body stores.

South Dakota State examined this scenario (using mature cows) by comparing the effect of weaning date on performance of the beef cows. They weaned half of the cows at the time of the first real cool spell (Sept. 14). The other half of the cows had their calves weaned at a traditional time (Oct. 23). The scientists then monitored body condition and rebreeding performance of the cows.

We should note that this study included two different nutritional levels: a low group to mimic an early winter or a dry summer; a moderate group to mimic more ideal summer and early winter seasons.

Only the data for those cows exposed to the low nutritional group are presented here. They more nearly reflect what may happen for 2- and 3-yearolds than will the moderately fed mature cows.

This data indicates that the 40 days earlier weaning allow the cows to regain 1/2 of a body condition score going into winter. More of the early weaned cows were cycling at the start of the breeding season, conceived early in the breeding season, and should wean heavier, older calves the following year. In addition, a small amount of high protein supplement (i.e. cottonseed meal or soybean meal) will enhance the cow’s ability to utilize the declining quality of the late summer forage. Therefore, this protein supplement can add more body condition to the young cows before frost arrives. This combination of management techniques should be a costeffective way to increase rebreeding rates of young spring calving cows.

The data from the cows that were in the “moderate” group indicate that middle-aged (4 to 7 years of age) in excellent body

Table 1. South Dakota study of earlier weaning on mature cows (source: Pruitt and Momont; 1994 South Dakota Beef Report) Weaning time September 14 October 23 condition in the fall did not significantly benefit from the earlier weaning. — Glenn Selk, Oklahoma State University Extension


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