| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
U.S. Department of Agriculture2,3,, Clay Center, NE 68933
Abstract
Postweaning growth and pubertal traits were studied in Hereford, Angus, Red Poll, Brown Swiss, Hereford-Angus crossbred (Hx A) and Angus-Hereford crossbred (Ax H) bulls from 7 through 13 months of age. Pubertal factors characterized included body weight, testicular size, hormone concentrations, sexual aggressiveness and sperm production. Puberty was defined as the age at which a bull first produced an ejaculate containing at least 50 x 106 spermatozoa with a minimum of 10% motility. Average pubertal age in days was 264 ± 9 for Brown Swiss, 283 ± 9 for Red Poll, 295 ± 9 for Angus, 296 ± 9 for Ax H, 300 ± 8 for Hx A and 326 ± 9 for Hereford bulls. Brown Swiss bulls were heaviest (295 kg), while Red Poll and Hereford bulls were lightest (258 and 261 kg) in body weight at puberty.
Concentrations of serum luteinizing hormone (LH) and testosterone (T), averaged across all bulls, increased linearly (P<.01) from 7 through 13 months of age. Breed differences in LH concentration were not observed from 7 months of age through puberty. Breed groups with high average T concentrations between 7 and 13 months of age reached puberty earlier than breed groups with low T concentrations. Bulls exhibited first sexual interest approximately 3 weeks before reaching puberty, and attained mating ability approximately 6 weeks after reaching puberty. Brown Swiss bulls were capable of completed matings 83 to 121 days earlier (P<.01) than other breed groups.
Although rather large differences in age and body weight at puberty existed among breeds, scrotal circumference at puberty (27.9 ± .2 cm) did not differ (P>.10). It is concluded that measurement of scrotal circumference may be a simple method of assessing puberty in beef bulls, regardless of differences in age, weight and breed, and should be a useful tool in the selection of early maturing bulls with minimal effort.
1 The authors gratefully acknowledge the laboratory expertise of Ms. Shari Ellis and the technical assistance of Mr. Ray Sampson, Mr. Steve Furman and Mr. Dave Mitchell with collection of animal data.
2 U.S. Meat Animal Research Center.
3 Mention of products of companies in this report does not constitute endorsement by the U.S. Department of Agriculture to the exclusion of others not mentioned.
This article has been cited by other articles:
|
|
 |
|
  E. Casas, D. D. Lunstra, L. V. Cundiff, and J. J. Ford Growth and pubertal development of F1 bulls from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu sires J Anim Sci, November 1, 2007; 85(11): 2904 - 2909. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Herrid, S. Vignarajan, R. Davey, I. Dobrinski, and J. R Hill Successful transplantation of bovine testicular cells to heterologous recipients. Reproduction, October 1, 2006; 132(4): 617 - 624. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E T Bagu, S Cook, C L Gratton, and N C Rawlings Postnatal changes in testicular gonadotropin receptors, serum gonadotropin, and testosterone concentrations and functional development of the testes in bulls. Reproduction, September 1, 2006; 132(3): 403 - 411. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. G. Kealey, M. D. MacNeil, M. W. Tess, T. W. Geary, and R. A. Bellows Genetic parameter estimates for scrotal circumference and semen characteristics of Line 1 Hereford bulls J Anim Sci, February 1, 2006; 84(2): 283 - 290. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
