Energy and protein requirements for maintenance and weight gain of Canindé goats supplemented on pasture in the semi-arid region

Abstract

The purpose of this study was to estimate the carcass composition, and energy and protein requirements for maintenance and weight gain of Canindé goats supplemented on pasture in a semi-arid region. Forty-six castrated animals, with initial body weight (BW) of 15.7 ± 0.96 kg, grazing in Caatinga were used. Six animals were slaughtered at the beginning of the experiment representing the initial carcass composition (reference animals; 16.1 ± 1.15 kg BW), while the other animals were randomly distributed in four treatments (concentrate supplementation at 0%, 0.5%, 1.0%, and 1.5% BW), with ten animals per treatment. When one of the animals of each group reached 25 kg BW, all animals in that group were slaughtered. The whole empty body was weighed, ground, homogenized, and sampled for further chemical analyses. The level of supplementation influenced dry matter intake, retained energy, and body weight gain of Canindé goats. The energy (kcal/kg) and fat (g/kg EBW) contents in the carcass of goats of 15, 20, and 25 kg were 2.29 and 86.11, 2.39 and 113.48, and 2.47 and 140.53, respectively. The minimum nitrogen losses were 188 mg N/EBW0.75. The net and metabolizable energy for maintenance were 72.11 kcal/EBW0.75/day and 2.19 g/kg EBW0.75/day, respectively. The net and metabolizable protein requirements were 2.19 and 1.88 g/kg EBW0.75, respectively. The net energy and protein requirements for weight gain ranged from 2.61 to 2.81 Mcal/kg EBW gain and 194.37–222.55 g protein/kg EBW, respectively, for animals from 15 to 25 kg BW. It is concluded that the energy and protein nutritional requirements of Canindé goats supplemented on pasture in the semi-arid region vary according to body weight.