EFFECTS OF NEONATAL ADRENALECTOMY AND CASTRATION ON HORMONAL CHANGES IN PUBERTAL BULLS

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Abstract
Plasma samples from intact, adrenalectomized, adrenalectomized and castrated and castrated bulls were assayed for LH, testosterone, androstenedione and oestradiol-17β from birth to 26 weeks of age. The adrenalectomized bulls, unlike the intact bulls, failed to show a rise in androstenedione at 14·5 weeks of age or a rise in testosterone at 20 weeks of age. Testosterone levels in the castrated animals remained below 0·4 ng/ml whereas androstenedione reached levels similar to those in intact bulls by 26 weeks of age. In all animals the concentration of oestradiol-17β in plasma remained below 25 pg/ml, although intact bulls had the highest levels. Levels of LH rose after castration but not after adrenalectomy. These data show that in bull calves absence of the adrenal glands during prepuberty delays the rise in pubertal testosterone by at least 10 weeks.

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