With limited feed supplies this winter, some cows have come through the winter in thin condition. Low cow condition prior to calving reduces the quality and quantity of colostrum which lowers calf immunity. It also limits the amount of milk the cow is able to produce resulting in lighter calves at weaning. Nutrient requirements for a lactating cow are approximately 25% higher than a cow in late pregnancy. This makes it much more difficult to have a thin cow gain weight between calving and the start of the breeding season.
One experiment at Clemson University, (Journal of Animal Science, 1986. 62:300-306) pre-calving cows were fed to have a body condition between 2.0 and 3.5, on a scale of 5. At calving, the cows were placed in one of four feeding groups. High; gaining 1 pound per day, medium; maintaining weight, and low; losing 1.5 pounds per day. A second low group was flushed with 8 to 13 pounds of grain per day for a 14 day period prior to the start of the breeding season.
On average, cows with a higher body condition score started cycling 13 days sooner than those in poor condition. They also became pregnant 7 days sooner than thin cows. Flushing the thin cows did improve weight gain but did not improve reproductive efficiency.
Thin cows at calving that lost weight up to the breeding season had a 25% lower pregnancy rate compared to those that maintained or gained weight. Calf weaning weights were also 26 to 33 pounds lighter compared to calves from cows that maintained or gained weight.
A similar study conducted at the University of Alberta (Berg and McElroy, 1965) also found that cows that lost weight between calving and breeding season had a 15 to 19% reduction in pregnancy rate.
Even though feed supplies are tight and expensive; an adequate feeding program that has animals gaining some weight between calving and breeding will have a large impact on next year’s calf crop.
For additional information on feeding cows between calving and breeding season, contact Barry at 403-741-6032 or bjyaremcio@gmail.com.