DIAGNOSTIC OF BULLS REPRODUCTION CAPABILITY FROM THREE LIVESTOCK FARMS OF THE UPPER MAGDALENA

The aim of this study was to evaluate the reproductive functionality of the bulls in the colombian region “Alto Magdalena”, analyzing the effect of age and breed type on semen quality and other important reproductive characteristics. The research was made in Paicol, La plata and Nataga (Huila ? Colombia), covering tropical dry forest and tropical humid forest life zones. Sixty bulls from different ages and breeds were randomly selected and evaluated under natural breeding conditions and without previous sexual rest, using the American Society of Therigenology (AST) recommended methodology. To evaluate the breed type effect on some reproductive characteristics, a completely random design was used, with three treatments and different repetitions for treatment: T1: Bos indicus, T2: Bos indicus x Bos taurus y T3: Bos taurus. To evaluate the age effect, a design was used with seven treatments and different repetitions for treatment: T1: < 24, T2: 24.1 ? 30, T3: 30.1 ? 36, T4: 36.1 ? 42, T5: 42.1 ? 48, T6: 48.1 ? 54 y T7: > 54 months of age. In both designs it was applied the Minimal Significative Difference test, to determine the statistical differences and it was established a prediction model to the gross motility. The reproductive behavior expressed in the seminal material quality, libido and the rest of the reproductive characteristics of the bulls in the Colombian region “Alto Magdalena” was between the normal values. The breed type didn't have significant effect on the evaluated reproductive characteristics. Except on scrotal circumference and ejaculated volume did not have a transient effect on the analyzed variables. The prediction model for gross motility (Y), from a given value for scrotal circumference (X) is: Y = (1.90275)(X).