2.7. Statistical analysis
Body weight, scrotal circumference, gonado-somatic index, testosterone concentrations, Sulfo-NHS-Biotin parameters and the frequency of each sexual behavioural event were compared with an ANOVA for repeated measurements. The residues of all the sperm parameters were normalised with square root transformation before the statistical analysis. The statistical model considered the group (AR or DR), age (weeks), and the interaction between group and age as fixed effects, and the lamb into each group as a random effect. Post hoc comparisons were performed with least significant difference. The age at puberty and the age at which the lambs reached their maximum scrotal circumference were compared by ANOVA.
To analyse the response to the GnRH challenge, the relative percentage of change in serum testosterone concentration (respect time 0: immediately before buserelin administration) was compared with an ANOVA for repeated measures. Separate analyses were performed for each dose of buserelin (low and high), and included the effect of group (DR vs AR), time (hour) and the interaction between both.