Exigências nutricionais de cordeiros da raça Somalis brasileira

Abstract

The objective of the following work to determine the nutritional requirements of energy and protein in Brazilian Somali sheep. We used 48 sheep Brazilian Somali growing, non-castrated, age and body weight (BW) average of 60 days and 13.47 ± 1.76 kg respectively. After a 20 day adaptation period, eight animals were slaughtered and used as a reference for estimates of empty body weight (EBW) and initial body composition of other animals. The remaining animals were distributed in a randomized block design, with the treatments, diets with different levels of metabolizable energy (1.18; 2.07; 2.25; 2.42 and 2.69 Mcal/kg DM), with eight repetitions. The weight of slaughter animals was determined when the weight average of the five treatments was 28 kg. The net energy requirement for maintenance was estimated extrapolating the logarithmic regression equation of heat production, depending on the metabolizable energy intake (MEI) to the zero level of MEI. The daily excretion of nitrogen (N) was estimated by extrapolating to N consumption regression equation (g/BW0.75 kg/day) as a function of the N retention (g/BW 0.75 kg/day) for consumption zero. They were adjusted regression of log equations fat content, protein and energy in the logarithm of EBW animals. The concentration of net energy for maintenance diet was obtained by dividing the heat production in fasting, the DMI to maintain energy balance in g DM/kg EBW0.75. The validation of the SRNS model was performed using the simple linear regression model fit between the predicted values (independent variable) and observed (dependent variable), variables were analyzed DMI and BWG. The body composition was determined using the composition of the right half carcass, as well as a sample of the section HH, obtained from the left crankcase half. In middle housing cooled left, retreated cutting the section HH, the cross section of the 9th-10th-11th rib at the point corresponding to 61.5% of the distance between the sectioned vertebrae and the beginning of the 12th rib cartilage in then, the HH section was ground in grinder industrial and homogenised meat. The average daily gain and empty body weight gain increased linearly with increasing metabolizable energy levels. But the final body weight, body weight at slaughter, empty body weight, dry matter intake and metabolizable energy intake showed a quadratic effect (P<0.001) with increasing energy level. Energy and fat EBW of the animals increased from 2.77 Mcal/kg to 209.17 g/kg to 3.47 Mcal/kg to 294.08 g/kg EBW, respectively, and increased the BW 13.00 to 28.70 kg. Consumption of nitrogen showed quadratic effect with point of maximum of 2.59 Mcal/kg DM of metabolizable energy, corresponding to the maximum consumption of N of 2.90 g/kg BW0.75/day. As for the nitrogen retained daily, there was a positive linear correlation with the increase in metabolizable energy levels in the diets. There was a decreased amount of protein in the empty body of animals with increased EBW, from 143.71 to 122.52 g/kg EBW, when the animals increased the body weight of 13.00 to 28.70 kg. The daily excretion of N was estimated at 0.128 g/BW0.75 kg/day. The body composition of Brazilian Somali sheep ranges from 538.28 to 593.93 g/kg EBW for water, from 228.17 to 353.13 g/kg EBW for fat, 114.53 to 157.93 g/kg EBW for protein and from 17.94 to 31.68 g/kg of EBW of mineral matter, for diets containing 1.18 to 2.69 Mcal/kg DM, respectively. The net energy requirement for maintenance is 45.63 g/kg EBW0.75/day. The increase in animal weight of 13.00 to 28.70 kg BW increases the deposition of fat from 283.75 to 398.93 g/kg EBW and energy of 3.42 to 4.30 Mcal/kg EBW. The protein requirement for maintenance is 0.80 g/BW0.75 kg/day, with a decreased protein requirement for EBW of 119.72 to 102.07 g/kg EBW, as the weight increases by 13.00 to 28.70 kg. The use efficiency of metabolizable energy for maintenance is 0.67. Already use efficiency of metabolizable energy for gain varies from 1.85 to 0.43 for diets containing 1.18 to 2.69 Mcal/kg DM, respectively. The net requirements of energy and protein increase with increasing body weight and increase in body weight gain of Brazilian Somali sheep. The model Small Ruminant Nutrition Systems is sensitive to predict dry matter intake, however, underestimated in 5.18% the average daily weight gain. The section HH satisfactorily estimated the chemical composition of water, protein and fat in the carcass and empty body, while the mineral content was underestimated around 27.07% 14.91% housing and empty body. The water content, crude protein and carcass fat can be predicted by section HH. Finally, the chemical composition of section HH can be used to replace the chemical composition of the carcass to predict chemical composition of empty body in Brazilian Somalis sheep.