Feed intake and nitrogen utilisation by growing goats fed by-product based diets of different protein and energy levels (original) (raw)

1996, Small Ruminant Research

Nine local (Guyana, South America) cross-bred, intact, growing, male goats (6 months old with mean ( f SD) initial BW of 19.9 f 2.8 kg) were used in two metabolism trials. They were fed diets formulated to be iso-caloric with protein levels of 51, 76, 91, 108 and 127 g CP kg-' DM (Trial 1). Trial 2 goats were fed diets formulated to be iso-nitrogenous with energy density values of 7, 11, 12, and 14 MJ DE kg-' DM. Diets contained ground untreated sugarcane bagasse as the sole roughage source ranging from 253 to 540 g kg-' DM. Each diet was pelleted to minimise differences in physical form and to prevent sorting and selection. The overall mean DMI values (+ SD) for Trials 1 and 2 were 25.0 + 1.4 and 29.8 _+ 4.1 g kg-' BW, respectively. Trial 1 DMI showed a (P < 0.00 I) linear increase with N intake which accounted for 56% of the variation of DMI and an increase of 33.1 g per unit increase of N. Both OM and DE intake increased (P < 0.05) with increasing dietary protein levels. However, when diets of varying energy levels (Trial 2) were fed only DE intake increased (P < 0.05).