ADMINISTRACIÓN DE TESTOSTERONA EN ALPACAS CON ADHERENCIAS PENE-PREPUCIALES

Abstract

In order to study the effect of testosterone on penis-prepucial adherences,twenty alpacas were selected from a flock of male tuis. Fourteen and six of the selected animals were one and two years old respectively, from which 90% showed almost complete penis-prepucial adherence (0 and 1 grade) and the remaining showed a grade 2 adherence. Animals were randomly assigned to two treatment groups (T_oand T₂) according to age and adherence grade in order to achieve experimental equilibrium. Each T₂ animal received 327 mg of testosterone i.m. distributed in three doses,on a two-week interval. Both body weight and adherence releasing grade were evaluated fortnightly; testicular size and sexual behaviour were recorded weekly. A larger releasing adherence was observed in one-year-old alpacas in T₂, specially between weeks sixth and ninth, after treatment (P<0.08). There was a treatment-age interaction(P<0.05)in body weight, in which one-year-old alpacas from T₂had higher body weight gain than those from T₀(P<0.05), and than those of two-year-old alpacas from T₀ and T₂(P<0.01). Treatment-age interaction was also significative on testicular size(P<0.05) because of alarger increase in length and width in one-year-old males from T₀than in the other animals(P<0.01), while the smallest increase(P<0.01) was showed by one-year-old males from T₀ and T₂. Sexual behaviour was absent in almost all males exposed to females in heat.