Behavioral effects of castration and testosterone propionate replacement combined with ACTH in the male domestic duck (Anas platyrhynchos L.)

Abstract

Twenty-one adult male ducks were bilaterally castrated, then injected as follows for 17 consecutive days: testosterone propionate (TP; N = 6; 5 mg/day/bird) + ACTH (20 IU/day/bird); TP + saline (N = 6); oil + ACTH (N = 5); oil + saline (N = 4).The birds were repeatedly observed under standardized conditions, before castration as well as during the hormonal treatments. Their behavioral performances were compared to those recorded in a sham-operated group (N = 6).Castration resulted in a decrease of most social activities -aggressive and sexual behavior, social displays -and of the general level of activity.TP administration resulted in a complete reversal of these effects. ACTH treatment did not by itself induce any detectable change.The results are discussed in view of the present knowledge of the endocrine regulation of behavior in ducks. Evidence is also provided that individual differences in behavioral performances cannot be directly related to differences in androgen plasma levels.

Individual variation and the endocrine regulation of behaviour and physiology in birds: a cellular/molecular perspective

“…Other studies have failed to find such correlations. For example, the amount of sexual behaviour and social displays exhibited by castrated ducks injected with a standard dose of testosterone propionate is significantly correlated with precastration activity (Deviche 1979). Similar results were observed in zebra finches (Taeniopygia guttata;Arnold 1975) and ring doves (Streptopelia risoria).…”

“…Unexpectedly, attempts to correlate, at a specific time point, individual plasma testosterone concentrations with measures of male sexual behaviour produced extremely disappointing results. For example, there was no relationship between individual variations in sexual behaviours (grabbing female neck feathers, 'pumping', mounting and actual copulations) and plasma testosterone in a large group of 30 male domestic ducks (Balthazart et al 1977), despite the fact that all these behaviours had been shown to be testosterone-dependent by the castration-replacement approach (Balthazart & Stevens 1975;Balthazart & Hendrick 1979;Deviche 1979).…”