Relationship of age to seasonal levels of LH, FSH, prolactin and testosterone in male, white-tailed deer

Abstract

1.1. Seasonal levels of LH, FSH, Prolactin (PRL) and testosterone (T) were determined in blood plasma of penned male white-tailed deer, ranging in age from 2 to 10yr.2.2. Peak levels of T (observed around the rutting season in November) gradually increased until the 7th yr and then they began to decline slowly; a sharp decrease was registered in the 10th yr.3.3. Peak levels of PRL (measured in June) steadily increased until the 6th yr and then dropped rapidly in the 8–9-yr-old group.4.4. Peak concentrations of FSH (observed during September–October) rose gradually until the 6th yr, decreased in 8-yr-olds and then increased again in the 9th and 10th yr of life.5.5. On the other hand LH maxima (occurring during July–September) were rising until the 4th yr and then remained steady until the 6th yr. LH peaks in the 8th and 9th yr were more than 50% higher than that of the 4–6th yr.6.6. These data indicate that increasing peak levels coincide with approaching “prime male age” around 5–7 yr.7.7. In senior bucks (9–10 yr) decreasing gonadal function may be the sign of diminished responsiveness to pituitary hormones since gonadotrophins are elevated to the “castrate-type” levels.