Research Progress Report 127
Project 1306          April, 1964
Synchronization of Estrus in the Beef Cow On the Southern Indiana Forage Farm
Robert Garrigus and R. C. Peterson, Department of Animal Sciences; C. J. Callahan, Veterinary Clinics
One management practice that would make artificial insemination more attractive to the beef cow herd man would be to control the estrus cycle in the entire cow herd so they would come "in heat" and be bred over a two, three or four-day period. This would be of special benefit to the cattleman because (1) he could breed all of his cows to one outstanding bull, and (2) the calf crop would be dropped over a short period of time. Reduced breeding and parturition intervals would improve labor efficiency and yield calves that would be of uniform age and size.
Objective
The objective of this steroid project was to evaluate the efficiency of estrus synchronization in the-beef cow herd with respect to ovulation, reproductive efficiency and post-treatment reproductive response.
Experimental Technique
Fifty-two grade Hereford cows from the Forage Farm herd were used for this project. They were allotted into two groups of 26 each on the basis of age and their most recent parturition date. These cows had calves on them during the experiment.
All cows were examined prior to the experimental period to make sure the reproduce
tive organs were functioning (cycling)properly. Those cows that were not cycling were eliminated from the final selection of experimental animals.
All cows (both groups) were fed 2 pounds of a supplement which consisted of 1 pound of ground shelled corn and 1 pound of soybean oilmeal for 5 days prior to the feeding of the hormone which was the agent that controlled estrus. This pre-experimental feeding was to get the cows accustomed to eating the supplement.
The supplement was the carrier for the primary premix containing the hormone.
The primary premix contained 1 gram of the Lilly 33324-CAP per pound. This primary premix was then mixed with equal parts of ground shelled corn and soybean oilmeal at the rate of 10 pounds per ton.
This results in 5 milligrams of hormone per pound of supplement or a daily dosage of 10 mg. of CAP per cow daily, as 2 pounds of supplement were fed daily.
The actual feeding of the supplement containing Lilly:33324CAP to the treated group and the supplement without the CAP to the control group was begun on April 26 and withdrawn on May 13. The experimental feeding period continued for 18 days.
PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana