Economic implications of factors affecting weaning weight production in a herd of charolais cattle

Includes bibliographical references (leaves 142-152)The analysis of production and economic effects of calving difficulty, calf death loss, weaning weight and calving interval was based on the performance data of a herd of Charolais cattle in East Central Texas. The regression of percent calving difficulty on birth weight showed a quadratic relation to the level of calving difficulty with the lowest number of cases occurring in the 32-41 kg birth weight range. Calving difficulty in 3-year-old cows was 24.8% higher than in 5 through 8-year-olds. Cows 3 and 4 years old experienced significantly more difficult births with male calves than with female calves. Calves born in February, March, April, and May experienced 6.7 to 15.1% more difficult births than calves born in all other months. Sire effects on percent calving difficulty ranged from 0 to 29% with a mean of 8.6%. The regression of percent calf death loss on birth weight showed a quadratic relation to calf survival with more calves lost at both extremes of the birth weight range. Death loss was minimal in the 32-41 kg range. Calf death losses were 3.3, 7.5, 31.2, and 73.0% for calving scores 1, 2, 3 and 4, respectively. In births from 3-year-old cows, percent calf death loss was 10% higher than in cows 5 through 9 years old. Losses were 4.7% higher in male than in female calves. ..