Exigências energéticas e proteícas de ovinos Santa Inês em crescimento

• Ano de defesa: 2009
• Autor(a) principal: Regadas Filho, José Gilson Louzada
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Zootecnia; Composição corporal; Mantença; Ganho de peso corporal; Exigências energéticas e protéicas; Corporal composition; Maintenance; Profit of corporal weight; Energy and proteinic requirements
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/18767

This study was conducted to evaluate the influence of four concentrations of metabolizable energy in the diet of Santa Inês sheep in growing. Body composition, energy and protein requirements, efficiency of utilization of metabolizable energy for maintenance (km) and gain (kg), and evaluation of Small Ruminant Nutrition System - SRNS model in predicting dry matter intake (DMI) and average daily gain (ADG) were studied. Twenty-four Santa Inês sheep, non-castrated, with age of 50 days and average body weight of 13.00 ± 0.56 kg were used. After an adaptation period of 10 days, four reference animals were slaughtered to estimate the initial empty body weight (EBW) and body composition of the others animals. The remaining animals were distributed in a randomized block design with the treatment consisting of diets containing different concentrations of metabolizable energy (2.08, 2.28, 2.47 and 2.69 Mcal/kg of DM), with five replicates. The animals were fed until reach the slaughter weight of 28 kg. The net energy requirements for maintenance (kcal/kg EBW0.75/day) were estimated extrapolating the regression equation of heat production (HP) logarithm, in function of the metabolizable energy intake (MEI) to the zero level of MEI. The N daily excretion was estimated extrapolating regression equations of N consumption (g/kg BW0.75/day) in function of the N retention (g/kg BW0.75/day) for the zero consumption level, the negative intercept of the Y axis was considered as the endogenous N losses. Regression equations were adjusted between the logarithm of the fat, protein and energy contents and the logarithm of EBW. The derivatives of these equations enabled the estimation of net energy and protein for the gain of empty body weight (EBWG). The km and kg were estimated by the equations recommended by the Agricultural and Food Research Council - AFRC (1993)and by Harris (1970). Validation of SRNS model used the DMI and ADG observed and predicted by the model for each of the experimental animals. Model inputs were given for each animal individually as BW, DMI observed and also data of chemical composition of diets and environmental conditions. Validation was performed by using a model of simple linear regression between the predicted and observed values. The net energy requirement for maintenance was 50.72 kcal/kg EBW0.75/day. The N daily excretion was estimated at 277 mg/kg BW0.75/day and the net protein requirement for maintenance (NPm) at 1.73 g/kg BW0.75/day. The contents of energy and fat in EBW of animals increased from 1.91 and 85.18 to 2.78 Mcal/kg and 221.23 g/kg of EBW respectively, when the animals increased from 15 to 30 kg of BW. The content of protein in EBW decreased from 157.83 to 144.33 g/kg of EBW when animals increased their BW from 15 to 30 kg, respectively. The fat and energy concentrations deposited in the EBWG increased as the animals elevated their BW. The net energy for EBWG increased from 2.94 to 4.28 Mcal/kg of EBWG for body weights of 15 and 30 kg, respectively. The protein deposited in the gain decreased from 137.47 to 125.71 g/kg of EBWG for animals with 15 to 30 kg, respectively. The km estimated was 0.71. The estimation of km from the metabolizability (qm) of the diet, suggested by the AFRC (1993) equations, varied from 0.68 to 0.73 for the diet with ME concentration from 2.08 to 2.69 Mcal/kg of DM, respectively. The efficiency of use of ME to gain (kg), showed to be inversely proportional to the increase of ME concentration in the diet, ranging from 0.52 to 0.28 for the diets containing 2.08 to 2.69 Mcal/kg of DM, respectively. The demands of total dietary energy increased with the elevation of BW within the same range of gain. The total metabolizable protein requirement of an animal of 20 kg of BW and a gain of 200 g/day is 52.64 g/day, about 34% lesser than the recommended by NRC (2007). The DMI predicted by the SRNS model did not differ (P≤ 0.05) from the DMI observed, but the model overestimated the ADG at 5.18%. The present work together to build a database, which in future could be condensed to several others in a predictive model of performance and food planning, is useful in formulating rations more economically viable to set up Santa Inês sheep