Good body condition critical for calving, rebreeding

Written by Dr. Jim White on .

After several months of marginal forage and harsher environmental conditions, spring-calving herds often have lower body condition scores (BCS) than fall-calving herds. Body condition scores describe the relative fatness of a cow herd using a nine-point scale. A cow with a BCS of 5 is average and represents a logical target. A BCS 1 cow is ex­tremely thin, while a BCS 9 cow is extremely fat and obese. Evaluating body condition in midsummer and at weaning are important to ensure good BCS at calving. Good body condition is most important during the last trimester, but there are few economical ways to increase it once winter has arrived.

If your cows fall on the thin side of the BCS scale, ask yourself why. Is it because of drought, overstock­ing or parasitism? Whatever the cause, correction and supplemen­tation are necessary to improve BCS. Weaning earlier will certainly help, especially if the situation has adversely affected calf weight gains. Both cows and calves would benefit. Protein supplementation along with a bit of fermentable carbohydrates, such as 2 pounds of MFA Breeder Cubes, will increase dry matter intake, and weight gains of 1 to 1.5 pounds per day are reasonable.

Weaning time is also a good time to evaluate BCS in conjunc­tion with other examinations and vaccinations. Cows with low BCS scores should be separated and fed until they reach at least a level 5 at calving. All cows need to gain approximately 100 pounds to allow for fetal and uterine growth. Beyond that, cows need to gain 80 pounds for each increase in BCS.

Cows with extra body condition are better able to face severe weather. When wet and cold conditions pre­vail, normal feeding regimens may not maintain body condition, and increased energy may be necessary. Cows with BCS 6 and above have some additional stores to withstand such episodes.

BCS should be evaluated at calving and before breeding. Pairs should be moved to where more nutrient-dense feeds can be fed. The goal is to ensure that lactating cows maintain body condition and are gaining weight during the breeding season.

Thin cows will make up time on the reproductive schedule by weaning their calves early, which removes the suckling inhibition and the lactation nutrition requirement. Research has shown that thin cows with BCS 3 or 4 will respond with high cycling and con­ception rates soon after weaning. Calves must be weaned at 6 to 8 weeks of age if thin mama cows are expected to rebreed and maintain a 12-month calving interval. One method is weaning 6-week-old to 8-week-old calves every two weeks, which meets the physiologic requirements for the cows returning to estrus and ensures calves are old enough to consume dry feed.

The most critical time for early-weaned calves is the first two weeks post weaning because they are learning to eat dry feed. Offering creep feed is helpful along with attentive management and small weaning groups. Shelter and access to feed and water are requirements.

From an economic perspective, feeding the calves and salvaging the breeding season is more profitable than feeding thin cows that are still nursing calves. Cows whose calves were weaned early will have lower nutritional requirements, they will breed better, and their calves will be heavier and more uniform than if left at the side of thin dams.

Evaluating body condition in fall-calving cows is critical at the be­ginning of summer and at weaning. Cows that are thin in June may not gain sufficiently if calves continue to nurse. In this situation, the choice would be to wean the calves, per­mitting forage to be used for weight gain rather than lactation.

If fall-calving cows go into the breeding season in thin condition, economic options are limited. Early weaning is more of a risk for calf health and weight gain than for cow performance. These cows should begin calving with BCS 6 or greater and fed to maintain postpar­tum condition. An early and short breeding season gives an early and short calving season, which reduces the likelihood of bad winter weath­er affecting the breeding season.