Perímetro escrotal e características seminais de touros da raça Nelore selecionados para precocidade sexual

Lima, Francisco de Paula Antunes; Xavier, P.R.; Bergmann, Jose Aurélio García; Júnior, A.P. Marques

doi:10.1590/s0102-09352013000600003

Cited by 5 publications

(2 citation statements)

References 13 publications

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“…O mesmo foi observado para defeitos totais onde os tourinhos com 14 meses apresentaram o maior percentual com (43,2%), seguido pelos tourinhos de 16 meses (42,4%) e o menor percentual foi registrados para os touros com 18 meses com (18,2%). Lima et al (2013) em seu estudo sobre perímetro escrotal e características seminais de touros da raça Nelore selecionados para precocidade sexual, verificaram maior percentual de patologias maiores e menores em animais super precoces, isto é, àqueles com idades entre 14 e 16 meses. Em conformidade com os dados apresentados no presente estudo, os autores afirmam ainda que o número de defeitos espermáticos diminuiu para os animais precoces, àqueles com 18 meses, indicando progressiva estabilização das características seminais após a puberdade, devendo esta estabilização se manter até que o animal atinja a maturidade sexual.…”

Section: Resultsunclassified

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

et al. 2020

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O presente trabalho tem por objetivo avaliar a ecogenicidade do parênquima testicular de touros jovens correlacionando com puberdade precoce. O estudo foi desenvolvido com 39 tourinhos puros de origem (PO) da raça Nelore, com idade entre 12 a 18 meses. A coleta foi realizada mensalmente, onde foi registrado peso, medida da circunferência escrotal e ultrassonografia testicular. A coleta do sêmen foi realizada apenas em animais nas faixas etárias de 14, 16 e 18 meses. Os dados coletados foram organizados em planilha do programa Microsoft Office Excel 2010, para posterior analise utilizando-se o programa estatístico Minitab. Os animais foram separados em dois grupos, os que produziram sêmen e os que não produziram e então classificados em precoces, super-precoces e normais, as médias geradas pela anova foram comparadas pelo teste de Tukey. As variáveis foram correlacionadas pelo método de Pearson. A ecogenicidade do parênquima testicular não influenciou na produção espermática e na precocidade. Os animais precoces apresentaram peso e CE superior aos super-precoces e normais. Peso e idade apresentaram alta correlação, não houve correlação entre peso e média da escala de cinza e, circunferência escrotal e média da escala de cinza. Touros com 18 meses apresentaram percentual de defeitos total inferior a 30%. realização da ultrassonografia testicular não é adequada como indicador de precocidade sexual e produção espermática. A aferição do peso corporal e circunferência escrotal são ferramentas mais eficazes para predizer o potencial reprodutivo de touros Nelore (PO) jovens, sendo estas também, ferramentas de seleção economicamente mais eficientes.

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Section: Resultsunclassified

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

et al. 2020

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“…According to Lima et al (2013), this change in sperm morphology should decrease with life stage owing to the maturation of the seminiferous epithelium and consequent progressive stabilization of seminal characteristics, thus, reducing the percentage of defective spermatozoa. At D60, there was a reduction in physical semen parameters in vaccinated animals (P < 0.05), with 80% and 70% azoospermia in the groups that received 1.0 and 0.5 mL, respectively.…”

Section: Seminal Fluid Production and Qualitymentioning

confidence: 99%

Reproductive parameters of lambs immunocastrated with anti-GnRH vaccine

et al. 2021

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The objective of this study was to evaluate the testicular biometric, seminal, and plasma testosterone levels in lambs subjected to an anti-GnRH vaccine as a method of castration. Thirty entire, crossbred Santa Inês male lambs were randomly distributed into three treatment (T): T1 was the control group, with the administration of 1 mL of saline solution subcutaneously (SC); 1.0 and 0.5 mL of an anti-GnRH vaccine were administered SC in T2 and T3, respectively. Testicular biometric variables, physical and morphological variables of semen, and plasma testosterone concentrations were evaluated. At D60, there was a reduction in testicular length, width, thickness, and scrotal circumference of the immunocastrated animals regardless of the vaccine dose used (P < 0.05). A reduction in semen physical variables at both dosages (P < 0.05) was observed, with azoospermia, in 80% and 70% of animals in the T2 and T3 groups, respectively. At D60, the immunocastrated animals also showed an increase in spermatozoa defects (P < 0.05), whereas plasma testosterone concentration decreased (P < 0.05). Immunocastration of lambs using the Bopriva vaccine at doses of 1.0 and 0.5 mL is efficient in inducing azoospermia in up to 80% of animals, although two doses in a 30-day interval are necessary for it to be an effective and safe method. Efficacy was demonstrated through a reduction in serum testosterone levels, testicular biometry, and seminal fluid analysis. Considering the efficacy of both doses in this study, we recommend using the lower dose (0.5 mL), which will allow for a 50% reduction in vaccine costs.

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Weak genotype x environment interaction suggests that measuring scrotal circumference at 12 and 18 mo of age is helpful to select precocious Brahman cattle

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Carvalheiro

Teixeira

et al. 2022

Journal of Animal Science

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The aim of this study was to evaluate the genotype x environment interaction (GxE) for scrotal circumference (SC) measured at different ages using pedigree-based (A -1) and pedigree and genomic-based (H -1) relationship matrices. Data from 1,515 Brahman bulls, from the Cooperative Research Centre for Beef Genetic Technologies (Beef CRC) experimental dataset were used in this study. SC was adjusted to age and body weight measured at 6 months (SC6), 12 months (SC12), 18 months (SC18) and 24 months of age (SC24). Body weight (BW) measured at 6 months (BW6), 12 months (BW12), 18 months (BW18) and 24 months of age (BW24) were used as criteria to describe the environment for SC in each age. All the animals measured were genotyped using medium-density SNP chips (“50k” or “70k” SNP) and their genotype were imputed using a reference panel with 729,068 SNP. The environment gradient (EG) was obtained by standardizing the solutions of the contemporary groups obtained by Animal Model with BW as the dependent variable. Then, the reaction norms (RN) were determined through a Random Regression Model. The breeding values (EBV) were estimated using either A -1 or H -1. The rank correlation was obtained using Spearman’s correlation among the EBV estimated for the traits in analysis. For SC6 and SC24, higher estimates of heritability (h²) were obtained using A -1, when compared to those observed with H -1. In those ages, the improvement of the environment decreases the h² coefficient. On the other hand, the h² for SC12 and SC18 increased as the environment became more favorable, regardless of the matrix used. The RN for SC6 and SC24 estimated using A -1 and H -1 showed a decrease of variance from the worst to the best environment, an indication of existence of GxE. On the other hand, for SC12 and SC18, there were no significant differences between the EBV estimated in the lower and in the higher environments, regardless of the kinship matrix used, suggesting absence of GxE on those ages. Spearman’s correlation among EBV estimated using A -1 and H -1 in different EG were practically equal to unity for all traits evaluated. In our study, there was weak evidence of GxE effect on SC in ages suitable for selection for sexual precocity. So, the absence of GxE at 12 and 18 months means these ages are advantageous for measuring SC to selection for sexual precocity. The advantage is that no changes in classification were observed when the sires were evaluated in different environments.

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Perímetro escrotal e características seminais de touros da raça Nelore selecionados para precocidade sexual

Cited by 5 publications

References 13 publications

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

Reproductive parameters of lambs immunocastrated with anti-GnRH vaccine

Weak genotype x environment interaction suggests that measuring scrotal circumference at 12 and 18 mo of age is helpful to select precocious Brahman cattle

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