Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science


Thirty-three percent of the animals which comprised the fed slaughter market in 1966 were heifers (U.S.D.S., 1967). When heifers are compared to steers, the gain at a slower rate, require more feed under similar feeding systems and sell at a lower price. These are important economic considerations in view of the large number of heifers fed for slaughter. The meat from heifers has been shown to be equal to that of steers in eating quality. It, however, sells at a lower price because heifer carcasses tend to be fatter and to have more waste as fat trim than steer carcasses when fed to the same market grade. The margin of profit on which livestock feeders operate is usually small. Profits often depend on rapid and efficient live-weight gains because of frequent negative margins between buying and selling prices of the animals. The makes it necessary to analyze the rations and methods of feeding and to study ways in which they may be improved. One method available is hormone administration which many be in the form of an additive to the feed or an implant placed under the skin of the animal. The feed additive or implant furnishes no essential nutrients but are substances used in relatively small amounts to improve gain, feed efficiency or carcass quality. Relatively little research has been published on methods of fattening heifers for market. Since heifers make up a considerable portion of the fed cattle, more research is needed to study ways of improving feedlot performance and to determine the most profitable ways to feed them. This experiment was conducted to determine the effects of spaying and the effects of diethylstilbestrol and Synovex-H (200 mg. testosterone propionate and 20 mg. estradiol benzoate) implants on feedlot performance and certain carcass characteristics of spayed and nonspayed heifers.

Library of Congress Subject Headings

Heifers -- Feeding and feeds




South Dakota State University