Estádio de maturidade sexual e estimativas de parâmetros genéticos e fenotípicos de características reprodutivas e ponderais, em touros da raça Nelore

• Ano de defesa: 2004
• Autor(a) principal: Silveira, Thiago da Silva
• Orientador(a): Paula, Tarcízio Antônio Rego de
• Banca de defesa: Guimarães, José Domingos , Torres, Robledo de Almeida , Guimarães, Simone Eliza Facioni , Eler, Joanir Pereira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Medicina Veterinária
• Departamento: Biotecnologia, diagnóstico e controle de doenças; Epidemiologia e controle de qualidade de prod. de
• País: BR
• Palavras-chave em Português: Touro; Reprodução; Herdabilidade
• Palavras-chave em Inglês: Bulls; Reproduction; Heritability
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::REPRODUCAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/5042

The objectives of this study were: 1) to study the stage of sexual maturity, testicular format and the Pearson simple correlations among the reproductive and growth traits in young Nellore bulls with average of age of 21,5 months, appraised andrologicamente among the years from 1999 to 2003. This population had 78% of sexually matures bulls during the experimental period, and the long testicular formats (99,93%), mainly the moderate long format (66,19%) it went predominate in to population in every appraised year. The correlations in favorable sense, verified in this study were of the scrotal circumference and of the testicular volume with all the reproductive traits of testicular mensuration (scrotal circumference at 450 days of age, lengths and widths of the right and left testicles and testicular format), physical (volume, aspect, individual motility, gross motility and vigor of the ejaculated) and morphologic aspect of the ejaculated (larger, smaller, total defects and head, midpiece and tail defects) and growth (birth weight, weaning weight, weight and hip height at 550 days of age). 2) to esteem heritability values and genetic correlations among the reproductive (evaluated in the occasion of the breeding soundness evaluation) and growth traits. The heritability were: birth weight (0,22 ± 0,04), weaning weight (0,15 ± 0,03) and weight at 550 days of age (0,18 ± 0,04), hp height at 550 days of age (0,16 ± 0,04), scrotal circumference to the 450 days of age (PE450) (0,24 ± 0,05) and at breeding soundness evaluation (PE) (0,37 ± 0,05), length of the left (0,24 ± 0,05) and right testicle (0,26 ± 0,05), width of the left (0,29 ± 0,05) and right testicle (0,31 ± 0,05), testicular format (0,12 ± 0,04), testicular volume (0,33 ± 0,06), length (0,18 ± 0,04) and width (0,41 ± 0,06) of the seminal vesicles, testicular consistency (0,73 ± 0,06), volume (0,05 ± 0,02) and aspect (0,07 ± 0,03), gross motility (0,11 ± 0,03), motility (0,08 ± 0,03) and vigor (0,05 ± 0,02) of the ejaculated, larger (0,20 ± 0,04), smaller (0,03 ± 0,02), total (0,19 ± 0,04) spermatic defects and head (0,15 ± 0,04), midpiece (0,02 ± 0,01) and tail (0,17 ± 0,04) spermatic defects. The genetic correlations between the PE and the growth traits, physical and morphologic traits of the ejaculated was favorable. The PE is a good trait to evaluate and select young Nellore bulls due to its high heritability and favorable genetic correlations with growth and reproductive traits. 3) it esteems heritability value and genetic correlation among the trait Andrologic Aptitude (AA) in Nellore bulls at 21 months of age and the scrotal circumference at 450 days of age. For being a categorical trait (value of 0 and 1 was given to sexually immature and mature animals, respectively), to be considered the component of addictive genetic variance the method R was used. Heritability estimates for AA in a single trait analysis was 0,22 ± 0,0067, and 0,56 ± 0.23 in the two traits analysis with the scrotal circumference adjusted to 450 days (PE450). It can be inferred that the studied population presents genetic variability for trait AA, and that presented a favorable genetic correlation with the PE450.