INTRA-TESTICULAR TEMPERATURE AND FERTILITY OF BISON, CATTALO, AND HEREFORD YEARLING BULLS

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Abstract
Intra-testicular temperatures of seven bison (Bison Americanus), eleven Hereford (Bos taurus), and eleven Cattalo (1/8-to 3/8-bison), yearling bulls were measured by means of a thermocouple technique. The mean temperatures were 93.9 ± 4.0° F, 91.0 ± 3.7° F, and 86.8 ± 5.5° F for bison, Herefords, and Cattalo, respectively.Weight of one testis (sans epididymis) was recorded for each of the fertility-tested bulls. Mean testis weights were 53.3 ± 6.8 grams for the bison, 201.3 ± 12.9 grams for the Herefords, and 89.9 ± 26.2 grams for the Cattalo. Breed differences in testis weight were significant at the 1 per cent level of probability. The Cattalo and Herefords did not differ significantly in body weight or age. However, the bison bulls weighed significantly less than the Cattalo and Herefords.Fertility estimates were obtained on four bison, four Herefords, and the eleven Cattalo by removal of a testicle from each and microscopic examination of semen taken by smear from the tail of the epididymis. No spermatozoa were present in the bison samples; all of the Herefords and one of the Cattalo had good sperm concentration; three other Cattalo bulls appeared to have a low degree of fertility, as indicated by the presence of a few spermatozoa, and no spermatozoa were present in seven Cattalo samples.The results of this study indicated that the yearling bison bulls may have been sexually immature.

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