Seleção de touros jovens da raça Nelore através do exame andrológico e do comportamento sexual

Abstract

The reproductive capacity of the bull is one of the most excellent characteristics of the cut flock and the use of reproducers with low fertility can result in great economic losses, being thus, in this the objective of this study, was to select animal of the Nelore race, with age between 20 and 24 months, to analyze the taxes of fertility in different relations bull: cow. 98 young bulls of the Nelore race had been used, that had passed for zootécnica evaluation, being the chosen teams (N = 85/ 86,73 %), submitted to the breeding soundness examination. After this procedure, the apt ones to the reproduction (N = 70/82,35 %), had been one week evaluated how much to the sexual behavior, by 10, 15 and 20 minutes, the bulls of good and very excellent libido, had been distributed to perhaps in four groups, as it is followed: 1:25,1:40, 1:60 and 1:80 to evaluate the tax of gestation in the different relations bull/cow. The evaluation of the libido had satisfactory reply, a time that 31.12% had been classified with the excellent libido. The increase in the time of evaluation of the test of the libido of 10 for 15minutes reduced the percentage of classified bulls as questionable and good, and raised the percentage of bulls with good and very excellent libido. The frequency of moderate long forms (0,51 ≥ reason ≤ 0,625), (60,0%) and long (reason ≤ 0,5), (28,5%), had been observed with bigger constancy and minors of oval long form (0,626 ≥ reason ≤ 0,750), (11,4%), not being found animal with testicules with oval/spherical form (0,751 ≥ reason ≤ 0,875), (0,0%) and spherical (reason > 0,875), (0,0%). The correlation between the forms testicular, the scrotal perimeter, characteristic morphologic physics and of the semen and libido in this study had been next to zero and it did not have significant correlation (P > 0,05). The reproductiveefficiency of each experimental group, 1:25, 1:40, 1:60, 1:80, was evaluated by the taxes of gestation to the end of the station of sum of 90 days (86,4; 84,0; 85,3; 84,1 %), respectively, showed not to have association between treatments (P = 0,50), independently of the adopted treatment, the prenhez taxes had been to the same ones to the 30, 60 and 90 days.