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Journal of Dairy Science Vol. 50 No. 10 1679-1682
© 1967 by American Dairy Science Association ®
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Aging Phenomena in Spermatozoa. II. Estrous Cycle Length After Unsuccessful Insemination with Spermatozoa of Varying Age

G. W. Salisbury and F. H. Flerchinger1

Department of Dairy Science and the Statistical Service Unit, University of Illinois, Urbana

ABSTRACT

A statistical study of the length in days of a total of 159,038 intervals between inseminations following an initial, eventually unsuccessful insemination, classified by the age of the spermatozoa used for that in-insemination (kept at about 4 C for several days after collection), revealed that the proportion of the total returns to service occurring within 24 days or 30 days after insemination increased significantly as the age of the spermatozoa increased from two to five days after collection. This change reflected the decreasing capacity of the spermatozoa to initiate fertilization. Such observations of an increasing proportion of cows displaying an estrous cycle approximately of the normal length, after insemination with aged spermatozoa, have been interpreted by others as indicating that the aging of spermatozoa was associated only with decreasing fertility and not with an increasing incidence of embryonic and early fetal death. However, the longer the spermatozoa were aged before use, the higher the proportion of cows seeming to be pregnant at the time of initial assay which later came back into estrus. It is emphasized that it is this highly significant statistical change in the proportion of apparently pregnant cows which later are in estrus and reinseminated which constitutes the appropriate estimate of faulty embryogenesis in cattle.

FOOTNOTES

1 Present address: Office of the Superintendent of Public Instruction, Olympia, Washington.






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Copyright © 1967 by the American Dairy Science Association ®.