Managing Nutrition and Body Condition
A successful heifer development program produces females who will conceive early, calve without difficulty, and breed back in a timely fashion. None of these are achievable if body condition is neglected. Nutrition is an essential component to heifer development that is often completely under the control of the producer.
Contrary to some beliefs, it is important to provide heifers with adequate nutrition for growth and development. Although it was once thought that feeding heifers too much prior to breeding or prior to calving would lead to an increase in calving difficulties, this is not recommended today. Replacement heifers certainly should not be over-conditioned, but inadequate body condition as a heifer will hinder the lifetime production and performance of the cow. Replacement heifers should be fed so that they reach approximately 65% of their mature body weight at the time of breeding. Mature body weight can be estimated by averaging the body weights of the mature cow herd that they heifers came from. For example, if the average mature body weight of the cow herd is 1300 lbs, heifers should be at least 845 lbs. at breeding. Dividing this figure by the number of days until the start of breeding season will give you a target average daily gain for heifers to reach breeding weight.
Puberty in beef heifers is initiated when a critical body weight is achieved. This critical weight varies among breed-types, and the age at which it is achieved may also vary. Crossbred beef heifers without brahman influence have been reported to reach puberty at 10-14 months of age, depending on breed type and plane of nutrition. Brahman-influence heifers may take longer to reach puberty. The first ovulation following onset of puberty is typically not associated with visible signs of heat, and conception rates for this ovulation are typically low.1 It is generally recommended that a heifer experience 2-3 heat cycles prior to the start of breeding season in order to help ensure she conceives early in the breeding season.
As discussed in previous blog posts, body condition score is an effective method of measuring nutritional intake in in beef cattle. Replacement heifers that are fed to achieve 65% of their mature body weight by approximately 15 months of age are typically a BCS of 5 or 6. Heifers should be in a BCS of 6 when they deliver their first calf. This added body condition helps prevent dramatic loss of condition as the heifer begins lactating while continuing to grow towards her mature body weight. Also, first-calf heifers in a body condition score of 6 will have higher conceptions rates during their second breeding season, compared to those first-calf heifers in lower body condition scores (i.e. BCS of 4 or 5).2
For more information on body condition scoring in beef cattle, visit the following website
https://extensionpublications.unl.edu/assets/pdf/ec281.pdf
or check out the Body Condition Score in Cattle Series.
References:
- Larson RL, White BJ, Laflin S. Beef Heifer Development. Vet Clin North Am – Food Anim Pract 2016;32:285–302.
- DeRouen SM, Franke DE, Morrison DG, et al. Prepartum body condition and weight influences on reproductive performance of first-calf beef cows. J Anim Sci 1994;72:1119–1125.