J. Anim Sci.
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J. Anim Sci. 1973. 36:67-71.
© 1973 American Society of Animal Science
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Effects of Injections of a Norethandrolone Suspension on Synchronization of Estrus and Conception in Beef Cattle1

Luther E. Smith, Jr. and Charles K. Vincent

Louisiana State University

Abstract

THREE experiments were conducted to determine the effectiveness of one to four injections of norethandrolone in synchronizing estrus in beef cattle (trials I, II and III) and to determine its effects on conception (trial III). The maximum percentages of cows exhibiting estrus in 1-, 3- and 5-day intervals ranged from 22 to 58%, 42 to 78% and 64 to 92%, respectively. A comparison of one, two or three injections (trial I) indicated a linear increase in synchronization response with increasing numbers of injections of norethandrolone for the 1-day response (P<.05) and for the 3- and 5-day response (P<.10). In the comparison of three vs. four injections (trial II), it was observed that the four-injection method improved the maximum 1-day response (P<.05) over the three-injection method but did not improve the 3- or S-day response. The first service conception rate of norethandrolone-treated cows was significantly (P<.05) lower (16 and 15%) than that of untreated cows (47%). Synchronization of estrus with injections of norethandrolone did not increase the total number of cows conceiving during the total 30-day AI period over the number of untreated cows.

Footnotes

1 Published with the approval of the Director of the Louisiana Agricultural Experiment Station. Appreciation is expressed to Dr. K. L. Koonce, Department of Experimental Statistics, for assistance in the data analysis.






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Copyright © 1973 by the American Society of Animal Science.