J. Anim Sci.
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J. Anim Sci. 1979. 49:647-650.
© 1979 American Society of Animal Science
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Effect of Clitoral Stimulation and Length of Time to Complete AI on Pregnancy Rates in Beef Cattle1

R. E. Short, J. B. Carr, N. W. Graves2, W. L. Milmine and R. A. Bellows

Livestock and Range Research Station, U. S. Department of Agriculture and Montana Agricultural Experiment Station, Miles City 59301

Abstract

An experiment was conducted to determine the effects that various durations of clitoral stimulation (CS) and length of time to complete inseminations (T-AI) have on first service AI pregnancy rates (PR). The experiment was conducted over 3 consecutive years on a total of 1,544 yearling heifers and lactating cows (2 to 11 years old). Cattle were randomly assigned within age, breed and sire to receive either 0, 3 or 10 sec of CS post-AI. In cows, CS increased PR but 3-sec CS was not significantly greater than 10 sec (51.7, 59.2 and 58.2% for 0, 3 and 10 sec). In heifers, the effect of CS on PR was nonsignificant and there was no effect of 3 sec vs 10 sec (57.5, 53.9 and 54.2% for 0, 3 and 10 sec). T-AI averaged 1.33 min, was longer in cows than heifers, was shorter in inseminations resulting in a pregnancy than those that did not and tended to decrease PR when times exceeded 4 minutes. Conclusions are that: (1) CS increased PR in lactating cows but not heifers; (2) the effects of CS in cows were modified by T-AI; (3) failure to obtain a response to CS in heifers was not explained by differences in T-AI; (4) T-AI should be 2 min or less, although an acceptable PR is possible at longer times if semen placement is at least at the second cervical ring.

Footnotes

1 This study was a contribution to Western Regional Research Project W-112, Reproductive Performance in Beef Cattle. Publication has been approved by the Director of the Montana Agr. Exp. Sta., Journal Series No. 921.

2 Present address: Barnum Route, Kaycee, WY 82639.






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Copyright © 1979 by the American Society of Animal Science.