Why Body Condition is Important in the Cow Herd

By Marty New

Body condition scores of beef cows at the time of calving have the greatest impact on subsequent rebreeding performance.

One of the major constraints in the improvement of reproductive efficiency is the duration of the post-calving anestrous period. If cows are to maintain a calving interval of one year, they must conceive within 80 days to 85 days after calving. Calving intervals in excess of 12 months are often caused by nutritional stress at some point, which results in thin body condition and poor reproductive performance.

Research has shown mature and young cows that maintain body weight have ample energy reserves before parturition, exhibited estrus sooner than cows that lost considerable body weight and consequently had poor energy reserves. Body weight change during pregnancy is confounded with embryo and placenta growth. Therefore, the estimation of body fat by use of body condition scores is more useful in quantifying the energy status of beef cows. The system of body condition scoring is an excellent estimator of percentage of body fat in beef cows.

The processes of fetal development, delivering a calf, milk production and repair of the reproductive tract are all physiological stresses. These stresses require availability and utilization of large quantities of energy to enable cows to be rebred in the required 85 days.

Added to physiological stresses are the environmental stresses of cold, wet weather on spring calving cows. In normal cow diets, energy intake will be below the amount needed to maintain body weight and condition. As the intake falls short of the energy utilized, the cow compensates by mobilizing stored energy and over a period of several weeks, a noticeable change in the outward appearance of the cow takes place.

Cows that have a thin body condition at calving return to estrus slowly. Postpartum increases in energy intake can modify the length of the postpartum interval. However, increases in the quality and quantity of feed to increase postpartum body condition can be very expensive. Improvement in reproductive performance achieved by expensive postpartum feeding to thin cows may not be adequate to justify the cost of the additional nutrients.

The influence of nutrition before calving is a major factor that controls the length of time between calving and the return to estrus. Thin cows with a BCS score of four or less at calving produce less colostrum as well as give birth to less vigorous calves that are slower to stand.

The impact of quality and quantity of colostrum will effect these calves’ immunoglobulin levels, thus harming their ability to overcome early calf-hood disease challenges. It is much easier to increase condition in cows before rather than after they calve. High nutrition after calving is directed first toward milk production. Feeding cows to gain condition early in lactation therefore leads to increased milk production but has little effect on body condition.

Cows prior to calving and through breeding should have a BCS of five or higher to have good reproductive performance. First-calf heifers should have a BCS of six. Spring-calving cows are still consuming harvested forages and lactating will generally lose one BCS following calving.

Over-stocking pastures is a common cause of poor body condition and reproductive failure. Proper stocking, year-round mineral supplementation and timely use of protein supplement offer potential for economically improving body condition score and reproductive performance.

An efficient way to utilize BCS involves sorting cows by condition 90 to 100 days prior to calving. Feed each group to have condition scores of five to six at calving. These would be logical scores for achieving maximum reproductive performance while holding supplemental feed costs to a minimum.

Body condition scoring has allowed cattlemen to continually evaluate their nutritional program. By evaluating cow condition at strategic times of the year, it is possible to coordinate use of the forage resource with nutritional needs of the cow herd so supplemental feed and hay needs are reduced to a minimum.

This article originally appeared in the February 2016 issue of Oklahoma Farm & Ranch.