Eighteen crossbred Anglo-Nubian does, 20 to 24 months and having a pre-trial average live weight of 20.9 +- 0.12kg were used to investigate dietary levels of energy and protein optimal for growth in the tropical environment of Samoa. The goats wereassigned on the basis of weight, to three treatment groups in a completely randomized design experiment and three experimental diets were offered at three protein and energy levels: 14.6, 13.4 and 12.4 percent crude protein (CP) and 12.3, 13.4 and 14.4 MJ GE/kg for eight weeks. The diets were designated as high protein low energy (HPLE), medium protein medium energy (MPME) and low protein high energy (LPHE). The letters P and E stand for protein and energy, respectively. Voluntary concentrate and forageintake values of 734, 680 and 650 g/doe/day and 512, 498 and 446 g/doe/day were obtained for the goats on diets HPLE, MPME and LPHE, respectively. Voluntary concentrate intake was higher (P<0.05) in goats offered HPLE followed by MPME and LPHE. Concentrate intake decreased linearly with increasing value of energy. Forage intake followed the same trend as concentrate intake (P<0.05). Total voluntary feed intake (concentrate + forage) decreased with increase in the levels of energy and not with protein levels. Average daily live weight gains were 95, 130 and 89 g/doe/day for HPLE, MPME and LPHE diets, respectively. There were significant differences (P<0.05) in daily live weight gains. The goats that had the MPME diet were higher (P<0.05) in live weightgain than those on HPLE and LPHE diets. Apparent organic matter digestibility values of 63.8 +- 0.04, 66.2 +- 0.02 and 62.2 +- 0.08 percent were obtained for the goats offered HPLE, MPME and LPHE diets, respectively. Apparent nutrient digestibility coefficients for crude protein and gross energy were significantly higher for goats on HPLE and MPME diets, respectively. However, HPLE diet was lower (P<0.05) than LPHE and MPME diets in apparent digestibility coefficients of gross energy. Crude fibre digestibility was significantly lower in the goats on HPLE diet. From these results the estimated optimal protein and energy requirements in a concentrate diet for optimum performance of crossbred Anglo-Nubian goats was 13.4 percent CP and 13.4 MJ GE/kg BW since growth rate was best at that level.
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