Animal Science, Department of
Date of this Version
2024
Citation
2024 Nebraska Beef Cattle Report
UNL Beef, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln
Abstract
A retrospective study was done utilizing 1,434 March- and May- calving Red Angus x Simmental crossbred cows and heifers from 2005 through 2019. Heifer weight as a percentage of mature body weight at breeding was used to conduct a regression analysis from 50 to 70% of mature body weight to determine the impact of body weight at breeding on reproductive performance. Heifer pregnancy rates and second pregnancy rates as 2-year-olds were greater for heifers at 60, 65, and 70% of mature body weight at breeding than heifers at 50 and 55%. However, heifer percent mature body weight at breeding did not influence pregnancy rates as 3-, 4-, and 5-year-olds. As heifer percentage of mature boy weight at breeding increased, calf birth weight and weaning weight increased. A greater percentage of heifers at a mature body weight of 50, 55, and 60% at breeding calved during the first 21d of the calving season than 65 and 70%. For producers, these results suggest that developing heifers at 60-70% of mature body weight at the time of breeding will likely have increased heifer pregnancy rates and as a 2-year-old. However, heifers below 60% of mature body weight at the time of breeding will likely have a higher percentage calve earlier in the first calving season, but calf weaning weights will not be increased. Although input costs would likely be reduced, the greatest challenge with developing heifers below 60% of mature body weight is rebreeding as 2-year-ols, however, there is no impact on subsequent pregnancy rates after 2-years of age.
Included in
Large or Food Animal and Equine Medicine Commons, Meat Science Commons, Veterinary Preventive Medicine, Epidemiology, and Public Health Commons