Sulfate supplementation of Angora goats: metabolic and mohair responses

K. Qi, C. D. Lu, F. N. Owens, and C. J. Lupton

Eight castrated male Angora goats were used in a repeated, simultaneous 4 × 4 Latin square designed experiment to evaluate metabolic and mohair responses of Angora goats to sulfate and mohair responses of Angora goats to sulfate supplementation. Goats had ad libitum access to isonitrogenous diets containing a 0.16 (basal), 0.23, 0.29, or 0.34% S (DM basis), which yielded N:S ratios of 12.7, 8.3, 6.8, or 5.5:1. Feed intakes were not affected (P > 0.20) by dietary S level. Quadratic increases (P < 0.05) to S supplementation were observed in grease and clean mohair production, grease and clean staple strength, and staple length. Mohair diameter, med fiber, kemp fiber, S, and cysteine contents were not affected (P > 0.05) by supplemental S. Averaged across the prefeeding, 2, 4, and 6 h postprandial sampling times, ruminal pH, ammonia N, total S, organic S, protein S, and plasma urea N and organic S concentrations were quadratically increased (P < 0.05) by supplemental S. Ruminal sulfate S, total sulfide S, and plasma sulfate S were linearly increased (P < 0.05) by supplemental S. Retention of N and mohair S yield exhibited quadratic increases (P < 0.05), but S retention exhibited a linear increase (P < 0.001) with increased S intake. Calculated by regression, the optimum dietary S concentration for maximum clean mohair production was 0.267% of dietary DM for a N:S ratio of 7.2:1, suggesting that the National Research Council N:S ratio of 10:1 is inadequate for Angora goats. The optimum level of digestible S was calculated to be 0.18% of the diet DM.