Effects of nutrition on seasonal changes in testosterone levels in young male reindeer ( Rangifer tarandus tarandus)

1. 1. Food restriction during autumn in male reindeer calves decreased peak testosterone levels at 4–6 months, and also at 16–17 months of age. 2. 2. Peak testosterone levels at the age of 16–17 months were significantly correlated to body weight at 6 months but not to body weight at 16 months of age. 3. 3. There were small secondary testosterone peaks (1–3 ng/ml) in March or April in 11 of 16 animals. 4. 4. Testosterone levels started to increase before summer solstice in 50% of the yearlings.