Energy and protein requirements of crossbred Holstein x Zebu steers fed different levels of calcium and phosphorus in the diet
DOI:
https://doi.org/10.5433/1679-0359.2016v37n4Supl1p2665Keywords:
Comparative slaughter, Efficiency, Growth, Maintenance.Abstract
The aim of this study was to determine the energy and protein requirements of crossbred Holstein x Zebu steers fed with or without the supplementation of dicalcium phosphate in the diet. Thirty-two steers with an average initial body weight of 377.5 ± 49.4 kg were used, of which four were initially slaughtered to estimate the empty body weight (EBW) of the animals. Twenty-four steers were fed ad libitum and were distributed in a completely randomized design with two levels of concentrate (30 and 60 %), and diets with or without dicalcium phosphate and four steers were fed at maintenance level, so that the body weight gain was equal to zero. After 84 days the animals were slaughtered. The animal tissues were sampled, and composted by two samples, denominated by “carcass” (bone, muscle and fat) and “non-carcass” (head, limbs, blood, hide, organs and viscera) for determination of the body composition. The net energy requirements (NEm) and metabolizable energy for maintenance (MEm) were obtained while relating heat production (HP) and metabolizable energy intake (MEI); meanwhile, the net energy requirements for gain (NEg) and the net protein requirements for gain (NPg) were obtained as a function of empty body weight (EBW), empty body gain (EBG) and retained energy (RE) in EBW. The daily net and metabolizable energy requirements for maintenance were 76.90 and 119.36 kcal/EBW0.75, respectively. The net energy requirements for gain can be obtained by the following equation: NEg = 0.0568±0.0025 × EBW0.75 × EBG1.095. The efficiencies of use of metabolizable energy for maintenance and gain are 64.4 and 29.68 %, respectively. The metabolizable protein requirements for maintenance are 4.14 g/BW0.75. The net protein requirements for gain can be obtained through the following equation: NPg = 236.36±30.06 × EBG - 19.84±6.14 × RE. We recommend the use of the equations obtained in this experiment to calculate the energy and protein requirements of crossbred Holstein x Zebu steers.Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2016 Semina: Ciências Agrárias
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
O Copyright dos manuscritos publicados pertence ao periódico. Como são publicados em um periódico de acesso aberto, eles estão disponíveis gratuitamente, para uso privado ou para fins educacionais e não comerciais.
A revista tem o direito de fazer, no documento original, alterações referentes às normas lingüísticas, ortografia e gramática, com o objetivo de garantir as normas padrão do idioma e a credibilidade da revista. No entanto, respeitará o estilo de escrita dos autores.
Quando necessário, alterações conceituais, correções ou sugestões serão encaminhadas aos autores. Nesses casos, o manuscrito deve ser submetido a uma nova avaliação após revisão.
A responsabilidade pelas opiniões expressas nos manuscritos é inteiramente dos autores.