Nota técnica: La actividad sexual de corderos a los ocho meses de edad como predictor de su actividad sexual adulta

Abstract

The possibility of predicting sexual activity of rams during their adult life at the earliest opportunity could be a very useful tool, especially in ram selection centers. With the aim of predicting serving capacity of adult rams by their performance at 8 months of age, 18 October-born rams were used. At 8 and 32 months of age (June) they were individually exposed for 20 min to three estrous ewes, and the num ber of approaches, attempted mountings, and mountings were recorded. Rams were ranked (1 to 18) after the calculation of their scores (total number of observed events). A regression model was applied to predict sexual rank at 32 months of age based on the 8-month ranking. Adult ram ranking and score were largely the result of the rank at 8 months of age (r2 = 0.594 and 0.365, resp.; p < 0.0001). The prediction of the rank at 30 months of age was outstanding for the worst rams, so that the worst 8 rams ranked at 8 months were the same than at 32 months of age. Serving capacity tests carried out with ram-lambs at early ages may be a tool to estimate sexual activity of adult rams, especially to eliminate the worst ram-lambs before they reach adult life.