Annual variation in reproductive parameters and sexual behaviour of Saint Croix rams in a semi-desert region in Mexico

The aim of this study was to determine the semen quality, sexual behaviour and testosterone (T) levels in Saint Croix rams under semi-desert climate conditions. Sixteen rams (70.6 +/- 12.5 kg; 24.1 +/- 0.3 months old) were randomly divided into a grazing group (GG, n = 8) and a supplemented group (supplemented individually with 1 kg.d(-1) of concentrate (156 g CP.kg(-1) DM and 2.5 Mcal EM.kg(-1) DM). SG, n = 8). Each group grazed on buffel, grass. Every two weeks, semen was collected, and sexual behaviour traits were evaluated. SG rams had greater body weight (P < 0.0001) and greater semen quality than the GG rams. SG rams had greater values for reaction time and lateral approaches than GG rams (P < 0.0001). No interaction was found between treatment and month for T concentration (P < 0.05); the SG rams had greater values during most of the months, but GG rams had greater values during September. Month had a significant effect on T concentration (P < 0.05) with the highest values in autumn. It can be concluded that Saint Croix rams are able to adapt to adverse environmental conditions and that supplementary feed prior to the mating season improves ram sexual behaviour.