To examine the effect of female proximity on circulating testosterone (T) concentrations, male French Alpine goats (Capra hircus; ages 4 to 5 yr old) were housed with visual contact with females (Near bucks, n = 5), or no visual contact with females (Far bucks, n = 5), prior to the onset of the breeding season (Experiment 1). After 10 wk, all males had visual contact with females. In a subsequent study (Experiment 2) Near (n = 10; ages 3 to 6) and Far bucks (n = 10; ages 3 to 6 yr old) remained in prospective housing conditions for the entire breeding season and body weight were measure weekly. To determine how T concentrations affect body weight castrated males (ages 5 yr old) were dosed with either 100 mg (n = 5), 25 mg (n = 5) or vehicle control (CON; n = 3) testosterone propionate (TP) 3x/wk subcutaneously (s.c.) and their body weight was measured every 3 mo for one year (Experiment 3). Males housed with visual contact to females had higher T concentrations than those not housed near females (P < 0.02; Experiment 1). After 10 wk, when all males were housed with visual contact with females T concentrations for the Far bucks increased significantly and were similar to those of the Near bucks. In the subsequent study (Experiment 2), Near bucks had significantly higher T concentrations and experienced a greater decrease in body weight loss compared to the Far bucks. Further, body mass loss was greater for castrated males treated with 100 mg TP compared to males treated with 25 mg or CON (Experiment 3). Taken together, these studies suggest T concentrations are lower when females are absent to minimize reproductive costs and increase when females are present.
All Science Journal Classification (ASJC) codes
- Food Animals
- Animal Science and Zoology
- Female influence
- Male body weight