The nutritional status or the body condition of beef females during the breeding season has a great impact on their reproductive performance. "Thin" cows will generally experience reduced reproductive performance.
The breeding season for herds calving in late winter and early spring will be getting underway around the first of April. High-quality forage available across much of the United States during this time will stimulate gain in condition and weight, which will have a positive effect on rebreeding. Fescue and Ladino clover pastures or Orchard grass and Ladino clover pastures will be of very high quality during the spring and will stimulate gain in both condition and weight.
Mature beef cows should calve in a body condition score (BCS) of 5 to experience profitable levels of reproduction. Condition scores range from 1 to 9, with 1 being extremely emaciated and 9 being extremely fat. If cows lose condition following calving and into the breeding season, they will have reduced rebreeding rates, while those that gain in both condition and weight will experience a higher level of rebreeding.
The beef females nutritional needs are greatest following calving than at any other stage during her production cycle. The nutrient demand for milk production drastically increases both energy and protein needs. The diet should be 58 percent to 60 percent total digestible nutrients (TDN) with 10 percent to 12 percent crude protein (CP). Generally, good quality pasture will provide the nutrient needs.
Cows "thin" at calving, (BCS <4), that gain weight during the breeding season will have a better opportunity to get pregnant than if they lose weight. These cows may not get bred in a 60-day period.
It is a challenge to get first-calf heifers, especially those selected for improved weaning weight and milk production, to gain weight following calving. These females require both a higher-quality feed and a longer period of time to recover from calving to have acceptable rebreeding performance. These females will need to gain 1.5 pounds (lb.) to 2.0 lb. per day during the breeding season. They should be managed separately from the mature cow herd and may require supplementation of both energy and protein.
Without good quality pasture, mature cows will need to be supplemented with 5.0 lb. of concentrate while first-calf heifers should be provided energy and protein supplement equal to about 1.0% of their weight.
Developing the breeding season to coincide with the availability of high-quality pasture will help to ensure adequate nutrition to stimulate gain in condition and weight of the beef females. Under most Tennessee conditions, this will be from the first of April to the last of June.
James B. Neel
Professor of Animal Science and
Extension Beef Cattle Specialist
University of Tennessee