Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Paul V. Fonnesbeck


Paul V. Fonnesbeck


James A. Bennett


Fred D. Provenza


Clell V. Bagley


Twenty-six range beef cattle ranches in southern Utah were surveyed by personal interview to obtain production data. The data were used to characterize the level of production efficiency in terms of calving rate, weaning rate, weaning weight, and net weaning weight in these operations; and to identify factors associated with differences in productivity.

The data revealed that productive efficiency was generally lower than the potential.

Mean calving rate of cows exposed for breeding was 83.4%. Stepwise regression involving calf death losses at or shortly after birth and heifer replacement rate accounted for 98.3% of the variance in calving rate. Calving rate differed (p< .05) with cow condition and herd type. Crossbred herds averaged the highest calving rate (90.3±6.3) compared to the straight bred herds (76.1±9 .9 ). Mean weaning rate was 80.1%. The difference of 3.2% between calving rate and weaning rate reflects pre-weaning death losses. Mean calving date, age of replacement heifer at first breeding and calving assistance influenced weaning rate but only for 31.5% of the total variance of weaning rate (p < .25). Crossbred herds had higher weaning rates (86.7±7.3) vs. straightbred herds (72.6±12.5). Also cows in moderate condition during lactation had higher weaning rates (83.0±10.2) compared to cows in borderline condition (76.2±12.9).

An average weaning weight of 20 1.6 kgs was obtained by the herds surveyed. Weaning age (p < .05) herd size, (p < .175) and herd type (p < .25) were important source of variation in weaning weight.

Mean net weaning weight of calves (pounds of calf weaned per cow exposed) was 178 kgs. Mean calving date and cow condition affected (p < .05) net weaning weights. Crossbred herds averaged net calf weaning weight 70.1 lbs higher than straightbred herds.

Positive correlations (.18 < r < .32) were observed between cow condition, range condition, and calving rate, weaning rate, weaning weight and net weaning weight. Correlations between calving rate, weaning rate, length of breeding season, number of cows per bull and heifer replacement were negative (-.25 < r < -.08).

A flowchart of a range beef cattle production system was conceptualized. The chart may be used to examine management alternatives.