The influence of sires used in artificial insemination on dairy cattle production traits in upper East Tennessee dairy herds
Date of Award
Master of Science
Don O. Richardson
J.T. Miles, E.W. Swanson, Joe A. Martin
The genetic Improvement of production traits in the dairy herds necessitates the use of breeding animals that are genetically superior to the average of the population. Since approximately 60 per cent of the dairy heifers born are required for normal herd replacements, genetic improvement is largely produced by the extensive use of out-standing dairy sires through artificial insemination programs. Artificial insemination (A.I.) provides an opportunity for the selection and extensive use of dairy sires that have demonstrated their genetic superiority. The extensive use possible via artificial insemi-nation is illustrated by the following figures: In 1962 (13) the average number of first services was 3155 per sire in A. I. The average number of first services varied from 1322 to 4629 per sire for organi-zations inseminating less than 100,000 cows and over 200,000 cows, respectively. The East Tennessee Artificial Breeding Association reported 25,164 first services to dairy sires with an average of 922 per dairy sire for 1963. The acceptance of artificial insemination of dairy cows has increased in the East Tennessee area in recent years. In 1963, it was estimated that over 20 per cent of the dairy cow population was insemi-nated artificially. A majority of these inseminations were to dairy sires in service in the East Tennessee Artificial Breeding Association. Since the East Tennessee Artificial Breeding Association was organized in November, 1947, there have been 332,614 inseminations to dairy sires. The best available estimates indicate that this represents over 90 per cent of the inseminations by commercial concerns in this area. It is evident that East Tennessee Artificial Breeding Association has had major responsibility for genetic improvement in dairy cattle production traits in this area. As the acceptance of A. I. continues to increase, sire selection committees will have more responsibility for the genetic improvement in dairy cattle production traits in the East Tennessee area. Therefore, it is important to determine the genetic improvement which has resulted from the use of A. I. in the upper East Tennessee area. Some preliminary studies in a few herds have shown the A. I . progeny to be superior to their dams and the DHIA herd average. Since these studies were limited to a few herds, and involved small numbers, their conclusions are inconclusive. The results could have been influenced by uncontrolled environmental conditions. Some environmental biases which could have been introduced are: the selection of herds studied, the change in the feeding and management practices, or differences in the season of freshening. This study was conducted to evaluate critically the influence on dairy cattle production traits that has resulted from the use of artificial insemination in the East Tennessee area.
Brower, John B., "The influence of sires used in artificial insemination on dairy cattle production traits in upper East Tennessee dairy herds. " Master's Thesis, University of Tennessee, 1964.