Comportamento sexual, concentrações periféricas de testosterona e perfil cromatográfico de proteínas do sêmen com afinidade a Heparina, em touros jovens da raça Guzerá
Twenty four Guzerat bulls from 24 to 34 months olds, andrologically evaluated as normal were submitted to a libido test, to study sexual behaviour in pen and pasture conditions, for periods of 10 and 15 minutes of observations and associate with andrologic (physic aspects, motility, vigour, sperm mass motility and concentration, semen volume; and morphologic aspects: major, minor and total sperm defects), scrotal circumference, breeding soundness evaluation for Zebu, body weight, age and serum testosterone concentrations. The evaluated behaviors were: 0) the bull did not show sexual interest for the female; 1) sexual interest shown only one time (example: smelling the perineal region); 2) positive interest for the female in more than an occasion (example: Flehmen reflex); 3) active persecution of the female with persistent sexual interest (example: mounting impulse); 4) one mount or attempt to mount, but no service; 5) two mounts or attempts to mont, but no service; 6) more than two mounts or attempts to mount, no service; 7) one service (complete mount or mating) followed by no sexual interest; 8) a service followed for sexual interest, including mounts or attempts to mount; 9) two services followed for no sexual interest; 10) two or more services followed by sexual interest, including mounts, attempts to mount and services; classifying the bulls in three categories: high libido - behaviors 7, 8, 9 and 10; average libido - behaviors 4, 5 and 6 and low libido behaviors 0, 1, 2 and 3. It was observed, in a general way, low reply of the animals to the tests, once that half of them were classified with average or high libido. Lower variation in the punctuation between the observation times was verified, in the individual or pen test with score 3.0 in five minutes and 3.3 in 15 minutes of evaluation (p>0.05). Otherwise, the biggest variation was registered in the collective pen test, with score 2.0 in five minutes of evaluation and 3.6 with 15 minutes (p0,05); já a maior variação ocorreu no teste coletivo em curral com escore 2,0 em cinco minutos de avaliação e 3,6 com 15 minutos (p<0,05). Quando se comparou os animais pela libido, constatou-se diferença (p<0,05) no peso corporal entre os animais de alta e baixa libido sugerindo efeito de ambiente na manifestação do interesse sexual e dos eventos comportamentais do cortejo, em touros jovens Guzerá. Encontrou-se diferença (p<0,05) nos níveis séricos de testosterona em touros com alta e média libido, quando comparados a touros de baixa libido. Buscou-se também associação entre os diferentes eventos de comportamento nos testes e tempos de avaliação utilizados, observou-se, de forma geral, associações favoráveis e de alta magnitude entre os eventos, sugerindo que touros que mais manifestam eventos em teste da libido são os com maiores chances de realizar a cópula. A associação entre a libido e idade, peso corporal e concentrações séricas de testosterona, independente do sistema de avaliação, reforçam o achado de influência direta destas características na expressão do interesse sexual em touros jovens Guzerá.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerai
