Fertility is the most important factor in determining profitability of beef herd. Deficiency of vitamins and other essential nutrients can impact bull reproduction components. The aim of this study was to evaluate the reproductive characteristics of pre-pubertal bulls supplemented with vitamin A. Forty Nellore bulls aged between 18 and 20 months were used. They were allocated into two groups: treated, which received vitamin A (2 ml/animal); and control, which were not supplemented. The animals went through andrological examination. Orchiectomy was performed for histopathological evaluation of the testis. Mean motility and sperm vigor were higher in the animals present in the treated group (p <0,01). No differences were found between the groups in the other andrological parameters evaluated. The structures analyzed in the histopathological examination presented normal appearance. The data suggest that Vitamin A supplementation can have positive results on sperm quality of pre-puberty bulls.
The objective was to determine the nutritional requirement of digestible threonine and the threonine: lysine ratios for light laying hens from 29 to 45 weeks of age. Two hundred Hy-Line-36 ® hens were distributed in a completely randomized design with five replicates and 10 birds per experimental unit and four treatments (5.50, 5.77, 6.05 and 6.30 g digestible threonine kg -1 ), establishing threonine: lysine of 69, 73, 76 and 80%. Four production cycles of 28 days each were evaluated: feed intake, feed conversion (kg dz -1 ), feed conversion (kg kg -1 ), egg laying percentage, weight and egg mass, percentage of egg components, internal egg quality and shell thickness. No effect of threonine levels was observed on egg production, weight and egg mass, internal egg quality, albumen and yolk percentage, specific gravity, shell thickness, feed intake, feed conversion (kg dz -1 ) and feed conversion ratio (kg kg -1 ). The ratio of digestible threonine: lysine to light laying hens in the period from 29 to 45 weeks is 69%, which corresponds to a daily consumption of 520 mg threonine bird -1 day -1 .Key words: amino acid; performance; egg production; internal qualityRelações treonina:lisina digestíveis para poedeiras leves no período de 29 a 45 semanas RESUMO Objetivou-se determinar a exigência nutricional de treonina digestível e as relações treonina:lisina para poedeiras leves no período de 29 a 45 semanas de idade. Duzentas aves Hy-Line-36 ® foram distribuídas em delineamento inteiramente casualizado com cinco repetições e 10 aves por unidade experimental e quatro tratamentos (5,50; 5,77; 6,05 e 6,30 g de treonina digestível kg -1 , estabelecendo a relação treonina:lisina de 69, 73, 76 e 80%. Foram estudados, quatro ciclos de produção de 28 dias cada, sendo avaliados: consumo de ração, conversão alimentar (kg dz -1 ), conversão alimentar (kg kg -1 ), percentual de postura, peso e massa dos ovos, porcentagem dos componentes dos ovos, qualidade interna dos ovos e espessura de casca. Não foi observado efeito dos níveis de treonina sobre o percentual de postura, peso e massa de ovos, qualidade interna dos ovos, porcentagem de albúmen e gema, densidade específica, consumo de ração, conversão alimentar (kg dz -1 ) e conversão alimentar (kg kg -1 ) e espessura de casca. A relação de treonina:lisina digestíveis para poedeiras leves no período de 29 a 45 semanas é de 69%, que corresponde um consumo diário de 520 mg treonina -1 ave -1 dia -1 .Palavras-chave: aminoácido; desempenho; produção de ovos; qualidade interna
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