| Abstract: | In a study to determine the relationship of pineal gland function and the onset of puberty, the size, hydroxyindole-0-methyl transferase (HI0MT) enzyme activity and melatonin content of pineal glands were measured in seventy-two Bos indicus and Bos Taurus male and female cattle. Significant differences in HI0MT activity (P < 0.05) were found in cattle 6, 12, 18 and 36 months of age. These age groups yielded 15.9, 15.5, 11.1 and 9.8 activity units, expressed as millimicromoles of melatonin synthesized per hour at 37C per gram of pineal tissue. Results also showed that enzyme activity diminished after 12 months of age in Bos taurus and after 18 months in Bos indicus cattle; this age being coincident with the onset of puberty. Melatonin contents varied inconsistently and did not follow the pattern of enzyme activity. Pineal gland size showed no differences between species, sexes or ages. |
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