| Summary: | The experiment was conducted to evaluate the growth performance of Thai indigenous male goats fed different levels of crude protein (CP) in total mixed rations (TMR). Twenty goats, average body weight of 15.84±2.35 kg were used. The four dietary treatments were randomly allocated into 5 blocks of the animals stratified on their initial body weight. Dietary treatments contained 8, 10, 12 and 14% CP (% of DM) with a concentrate: roughage ratio of 85: 15. The feeding trial lasted for 120 days. At the end of feeding trial, digestion trial was conducted by total collection method for a 7-day period. Increasing levels of CP contents (8, 10, 12 and 14%) significantly lead to increasing amount of crude protein intake (CPI), from 47.00 to 84.81 g/d and digestible crude protein intake, from 2.89 to 6.28 g/BW0.75/d (p<0.05). Increasing CP levels in TMR resulted in linearly increased goat’s final body weight (23.10, 23.42, 24.10 and 27.42 kg, respectively), weight gain(6.84, 7.37, 7.60 and 11.06 kg, respectively) and average daily gain (ADG) (56.97, 61.42, 63.30 and 92.13 g/d, respectively)(p<0.01). Crude protein digestibility (62.05, 67.39, 71.23 and 74.89%, respectively) was increased linearly (p<0.05) with increasing levels of CP levels in TMR. The results of the regression of CPI (g/BW0.75/d) on ADG (g/BW0.75/d) showed thatthe goats needed 3.57 g/BW0.75/d to maintain their body weight. The estimation of CP requirement for goat BW gain (g/g gain) was 0.49. It can be concluded that increasing levels of CP content in TMR not only improved CPI but also enhanced CP digestibility and promoted growth performance of Thai indigenous goats. According to Thai indigenous goat response linearly to levels of CP in TMR so that more research study is needed to evaluate whether feeding greater levels CP wouldimprove the growth performance.
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