Twenty-six Moxotó non-castrated male kids (initial mean 15 kg LW and 7-8 month old) fed a diet with 2.6 Mcal ME were used to evaluate the body composition and protein requirements for weight gain. At the beginning of the experiment, six animals were slaughtered as reference to estimate initial body composition and initial empty body weight (EBW). Subsequently, homogeneous groups of four animals were distributed a complete randomized experimental design into two feeding regimes: ad libitum feeding (AL) and feed restriction of 85, 70 and 55% of that consumed by the AL feeding group. The animals from each feeding regime were slaughtered at the time the group of the AL feeding approached 25 kg LW. Logarithm equation of retained body protein contents (BCP) was fitted on log10 of empty body weight (EBW). By deriving this equation, the predicting equation of BCP per kg of EBW gain was obtained. The protein content of the animals remained practically constant and ranged from 205.60 to 201.69 g/kg of EBW (reduction of 1.9%) and 15 to 25 kg with the increase of live weight. Despite of small body changes of net protein requirements (19.86 to 19.49), the fat: protein ratio increased with the increase in LV from 15 to 25 kg.
empty body weight; metabolizable protein; native goats; requirement