J. Anim Sci.
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J. Anim Sci. 1975. 41:1383-1389.
© 1975 American Society of Animal Science
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Effect of Age on Testicular Growth and Consistency of Holstein and Angus Bulls1

G. H. Coulter2, L. L. Larson3 and R. H. Foote

Cornell University4, Ithaca, New York 14853

Abstract

A total of 5,909 scrotal circumference and 5,373 testicular consistency (tonometer) measurements were made on Holstein bulls in seven artificial insemination studs. Comparable measurements were made on 339 Angus bulls. The multiple regression equation, Y = –4.67 + 47.26 log X – 11.74 (log X)2), where Y is scrotal circumference in cm and X is bull age in months, described the high rate of testicular growth in young Holstein bulls, limited growth in mature bulls, and a slight decrease in the oldest bulls. Angus tended to have larger testes than Holsteins up to 3 years of age, but they were surpassed after that age by Holstein bulls.

Regression of testicular consistency on age of Holstein bulls resulted in the equation Y = 20.83 – 9.06 log X + 2.47 (log X)2, where Y is the mean deflection averaged for weak and strong spring tonometers in mm and X is bull age in months.

Footnotes

1 The authors gratefully acknowledge Richard Cole, Michael Simkin, Dr. J. Hahn, Dr. Gary B. Anderson, Dr. Peter J. H. Ball and Ms. Jacqueline Schiavo for their assistance, Eastern A. I. Coop. Inc., The National Association of Animal Breeders and the North Central Biological Research Committee for financial support and all the bull studs mentioned in the paper for their cooperation.

2 Present Address: Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J-4B1.

3 Present Address: Department of Animal Science, University of Nebraska, Lincoln 68503.

4 Department of Animal Science.






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Copyright © 1975 by the American Society of Animal Science.