Prediction of metabolizable energy and protein requirements for maintenance, gain and fiber growth of Angora goats

A database was constructed for growing and mature Angora goats to estimate metabolizable energy (ME) and protein (MP) requirements for maintenance, whole BW gain (ADG), non-fiber tissue gain (TG) and fiber growth (clean fiber growth rate; CFGR). MP intake (MPI) was calculated from CP degradability properties and dietary proportions of feedstuffs. Variables, scaled by BW0.75, consisted of mean BW (kg), ME intake (MEI; kJ per day), MPI (g per day), ADG (g per day), TG (g per day; i.e., ADG corrected for grease fiber) and CFGR (g per day). For ME, the final simple regression equation for mature goats was MEI = 533 (SE = 18.8)+(43.2 (SE = 4.77)×ADG) (n = 77;R2 = 0.52). The final multiple regression equation for mature goats was MEI = 473 (SE = 49.85) + (37.2 (SE = 6.97) × TG) + (157 (SE = 52.5) × CFGR) (n = 48;R2 = 0.53). For MP, the final simple regression equation with a development data set for growing and mature goats was MPI = 4.30 (SE = 0.286) + (0.318 (SE = 0.0471) × ADG) (n = 68;R2 = 0.41), which resulted in unbiased prediction of MPI in an evaluation data set. The final multiple regression equation for growing and mature goats was MPI = 3.35 (SE = 0.440) + (0.281 (SE = 0.0486) × TG) + (1.65 (SE = 0.394) × CFGR) (n = 83;R2 = 0.46). In conclusion, ME requirements of mature Angora goats for maintenance, TG and CFGR were 473 kJ/kgBW0.75, 37.2 and 157 kJ/g (113 kcal/kgBW0.75, 8.89 and 37.5 kcal/g), respectively. MP requirements of growing and mature Angora goats for maintenance, TG and CFGR were 3.35 g/kgBW0.75, 0.281 and 1.65 g/g, respectively. © 2004 Elsevier B.V. All rights reserved.