Effect of Constant Environmental Temeratures, 50° and 80° F., on Appearance of Puberty in Beef Calves

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Abstract
Brahman, Santa Gertrudis, and Shorthorn heifer calves were raised from one month of age at constant environmental temperatures of 50° and 80° F., relative humidity of 50–70%, with equal periods of light and dark (experimental calves); controls were kept in an open shed exposed to Missouri weather. One outdoor Brahman did not mature; the remaining outdoor Brahmans and one 50° Brahman were apparently seasonally monestrous. All other calves were polyestrous. Brahmans at 80° reached puberty at a mean age of 463 days (19% of predicted age at mature weight); mean ages of all other experimental groups were between 290 and 440 days (11 to 14% of predicted age at mature weight). At puberty 80° Brahmans had achieved a mean of 60% of predicted mature weight (compared to means of 39 to 45% for all other experimental groups), a mean of 95% of predicted mature wither height (compared to means of 80 to 83% for all other experimental groups), and a mean of 84% of predicted mature chest girth (compared to means of 69 to 75% for all other experimental groups). One Shorthorn at 80° F. was similar to the 80° F. Brahmans in that superior heat tolerance, as indicated by rate of growth, was accompanied by delayed puberty. Copyright © . .

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