Protein requirement for maintenance of growing Boer crossbred doe

The effect of protein intake on nutrient metabolism and growth performance of female ≥ 50% Boer crossbred goats was investigated, along with protein requirements for their maintenance. Sixteen does were divided into four groups that were fed different levels of crude protein relative to the level recommended for purebred Boer by NRC (2007): 85% (0.85 M), 100% (1.00 M), 115% (1.15 M), and 130% (1.30 M). The experiment was conducted with does at 4-9 months of age. Feed intake, growth rate, nutrient digestibility, nitrogen balance, and microbial protein synthesis of the does were determined. The relationship between crude protein intake (g/kg^0.75 BW) and average daily gain (g/day) was tested using linear regression. It was found that crude protein intake, average daily gain, nitrogen balance, and microbial protein supply increased with dietary crude protein. Nutrient digestibility and nitrogen excreted via urine were not affected by treatments. At 4-6 months of age, Boer crossbred does require crude protein for maintenance to be ingested and absorbed at levels of 3.81 and 1.99 g/kg^0.75 BW, respectively, while at 7-9 months of age, does require 4.68 g/kg^0.75 BW ingested crude protein. Overall, growing does require 4.26 g/kg^0.75 BW ingested crude protein for maintenance during 4-9 months of age, which is 6.78% lower than the recommendation of NRC (2007).