J. Anim Sci.
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J. Anim Sci. 1975. 40:917-923.
© 1975 American Society of Animal Science
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Reproductive Physiology of the Stallion. V. Effect of Frequency of Ejaculation on Seminal Characteristics and Spermatozoal Output1

B. W. Pickett2, John J. Sullivan and G. E. Seidel, Jr.2

Colorado State University, Fort Collins 80523 and American Breeders Service3, Deforest, Wisconsin 53532

Abstract

In experiment 1, nine stallions were ejaculated for 4 weeks at each of three frequencies, 1X, 3X and 6X/week. After the extra-gonadal spermatozoal reserves had stabilized, in the last 2 weeks of the 4-week collection period, there were no significant (P > .05) differences in seminal volume/ejaculate, mounts/ejaculate or reaction time due to frequency of ejaculation. Mean concentration of spermatozoa/ml and number of spermatozoa/ejaculate were higher (P <.01) for the 1X and 3X ejaculation frequencies than for the 6X. Total spermatozoal output/ week was nearly identical for the 3X and 6X frequencies (35.2 and 35.3 x 109) and higher (P <.01) than the 1X frequency (11.4 x 109). Therefore, collecting stallions on alternate days would be a practical ejaculation frequency for inseminating mares. Percent motility, osmolality and total solids, as measured by refractometry, were not affected (P > .05).

In experiment 2, eight mature stallions were randomly assigned to two groups in a double-switchback experiment. Increasing the ejaculation frequency from one to two ejaculates per day twice a week increased (P < .01) the number of spermatozoa/week (26.2 vs 35.1 x 109). Gel-free seminal volume (58 vs 49 ml), spermatozoa/ml (221 vs 145 x 106) and number of spermatozoa/ejaculate (12.01 vs 5.5 x 109) were higher (P <.01) in first than in second ejaculates. Two ejaculates, 2 days a week would be a practical ejaculation frequency if semen were being collected for long-term storage.

Footnotes

1 The work at Colorado State University was supported in part by grants-in-aid from American Breeders Service and the National Association of Animal Breeders. Portions of these data were presented at the "First International Symposium Upon Equine Reproduction," Cambridge, England, 1974.

2 Animal Reproduction Laboratory, Department of Physiology and Biophysics.






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Copyright © 1975 by the American Society of Animal Science.