DIETARY-PROTEIN LEVEL AND RUMINAL DEGRADABILITY FOR MOHAIR PRODUCTION IN ANGORA-GOATS

Twenty-eight Angora goat doelings (average BW 22.1 kg) were used in a 150-d study to examine the effects of dietary CP level and degradability on mohair fiber production. A 2 x 2 factorial arrangement was instituted using conventional, solvent-extracted soybean meal (high degradability) or expelled, heat-treated soybean meal (low degradability) incorporated into low-(12%) or high- (19%) CP diets. Grease and clean mohair weights were greater (P < .05) in goats fed the diets containing 19% CP. Mohair fiber diameter was not affected (P > .10) by dietary CP level. Clean mohair weight tended (P < .08) to be higher in the goats fed diets containing expelled, heat-treated soybean meal. Body weight gains were not affected (P > .10) by CP level or degradability, whereas DMI increased (P < .01) with increasing CP level. Ruminal fluid pH and total VFA concentrations were not affected (P > .10) by diet. Ruminal ammonia N concentration increased (P < .05) as CP level in the diet increased, and postprandial changes in concentrations were less noticeable in the group fed expelled, heat-treated soybean meal. Plasma urea N (P < .001) and total protein (P < .01) concentration increased as dietary CP level increased. Plasma glucose was elevated (P < .001) 2 h after feeding in the goats fed conventional, solvent-extracted soybean meal, whereas glucagon concentrations were greater at 0 and 4 h in the group fed expelled, heat-treated soybean meal. This study demonstrates the inverse relationship between the quality and quantity of mohair fiber produced, and how fiber characteristics can be affected by dietary CP level and degradability.