Effects of dietary level of Leucaena leucocephala on performance of Angora and Spanish doelings.

Thirty Angora (16+/-2kg initial body weight) and 20 Spanish doelings (19+/-2kg initial body weight), approximately 8 months of age, were used in an 10 week experiment to evaluate effects of dietary level of Leucaena leucocephala on body weight (BW) gain and fiber growth. The control diet (CS) included 9% dry matter (DM) of formaldehyde-treated casein; other diets consisted of 15, 30, 45 or 60% DM of leucaena leaf meal (0.75% mimosine; 15, 30, 45 and 60l, respectively). Diets were formulated to be 2.13Mcal metabolizable energy/kg DM, and ranged in crude protein from 10 to 14% of DM. DM intake was greater (P<0.05) for 45l than for CS and 15l (710, 648, 815, 899 and 811g per day for CS, 15, 30, 45 and 60l, respectively) and similar (P>0.05) between Angora and Spanish doelings. BW gain was similar (P>0.05) among diets (48, 28, 38, 34 and 26g per day for CS, 15, 30, 45 and 60l, respectively) and between breeds. Mohair growth rate was lower (P<0.05) for 60 and 30l than for CS (1.34, 1.18, 0.94, 1.16 and 0.88mgcm(-2) per day, and mohair diameter was greatest (P<0.05) for CS and lowest (P<0.05) for 60l (27.7, 25.9, 25.1, 25.0 and 23.8µm for CS, 15, 30, 45 and 60l, respectively). Cashmere growth rate and fiber diameter for Spanish goats were similar among diets, and primary and secondary follicle activities for both Angora and Spanish goats were not affected by dietary treatments (P>0.05). Diet affected (P<0.05) plasma concentrations of urea, threonine, arginine, valine, phenylalanine, isoleucine, leucine and lysine, with concentrations increasing as dietary level of leucaena increased. In conclusion, diets of moderate to high levels (e.g., 45%) of leucaena with 0.75% mimosine can be fed to goats without adverse effects on BW gain or fiber growth. However, further study of the composition of leucaena-based diets appears necessary to achieve most efficient utilization.