|
A
Comparative Assessment of Breeding Systems for Small Beef Cattle
Operations
Constantine
L. Fenderson, Anthony D. Peterson, and Mozell Byars
Cooperative
Agricultural Research Program
Seminar Series
Tennessee State University, Nashville, TN
April 7,
1999
Introduction. The maintenance of a single
bull in a small beef herd tends to limit productivity and can be
expensive, thus leading to marginal profitability to the producer.
Artificial insemination (AI) may be a method of eliminating the
purchasing price of a bull and his annual maintenance cost. Productivity
may be improved by using semen of an outstanding proven sire; however,
low conception rate is generally associated with AI in beef cattle.
Objectives. 1) To compare the reproductive
efficiency and economic returns from naturally bred and artificially
bred small beef herds. 2) To compare post-weaning growth performance and
economic returns between calves produced by naturally bred cows and
calves produced by artificially bred cows.
Methodology. Fifty Angus cows and breeding
age heifers were used in this study. They were palpated one week prior
to the breeding season (April 7, 1997 to July 8, 1997), weight
stratified, and randomly assigned to two treatments (trts.) of 25
animals each with equal numbers of heifers and cows in each trt. Trt. 1
animals were pasture mated with one mature proven Angus bull. Trt. 2
animals were injected intramuscularly with 5 ml of Lutalyse on April 7,
1997, and again 11 days later. Eighty-four hours after the second
injection, each female was artificially inseminated with a single straw
of semen from a Southeast Select Sire registered Angus bull. Inseminated
animals were observed over three cycles and those returning to heat were
again inseminated by the AM/PM rule. After the breeding season, all
animals were grouped together and pastured during spring, summer, and
fall and wintered on mixed grass hay and 48% protein beef concentrate.
Results. Conception rate (rectal palpation
at the end of the breeding season) was 12% higher in the naturally bred
(NB) animals than the AI animals (84% vs. 72%). Calf crop percent
(number of calves weaned expressed as a percent f the number of females
exposed to the bull or AI) was the same for each trt. Average (avg.)
birth weight (wt.) of calves was numerically higher for trt. 1 (37.51
kg) than for trt. 2 (34.43 kg), however, such difference was not
statistically significant. Similarly, the avg. weaning wt. of calves was
slightly higher for trt. 1 (201.88 kg) than trt. 2 (198.45 kg); however,
such difference was not significant.
Impact. The results of this study indicate
that there were no significant differences between treatments. Given
that all input costs are equal for both trts. other than the purchase
price and annual maintenance cost of the bull and the cost associated
with the AI, it would appear that the economic benefits of using AI
outweigh those of the bull breeding program used in this study.
Return
to Seminar Series
|
