Relationships of ultrasonic estimates of fatness and muscling to production factors of angus bulls at Ames Plantation

Since man has domesticated beef cattle, he has strived to gain knowledge to aid in selection of those animals that will transmit the most desirable characteristics to their progeny. Rate of gain, type score, and other visual or measurable characteristics have been used as selection criteria in many production testing programs.

Ultrasonic techniques also have been used as aids in selection of beef cattle, sheep, and hogs. Since there is variation between half siblings, it is difficult to accurately predict certain characteristics of breeding animals based on carcass evaluation of their sibs. The use of an ultrasonic device to estimate certain characteristics that sire not always discernible to the eye shows promise, especially in the field of bull selection. The production tested Angus herd on Ames Plantation provided a set of bulls on which ultrasonic techniques could be used. The success with which ultrasonic evaluation methods have been used at this and many other stations prompted this study. The objectives were:

1. To ultrasonically determine hide, fat, and muscle thicknesses of bulls calved in the fall of 1962 and spring of 1963.

2. To compare fat deposition and muscle development patterns during the bull's growth period.

3. To determine the relationships among production factors, estimates of carcass composition and sale price.