Effects of feed restriction and subsequent realimentation on tissue and mohair fiber by growing Angora goats

R. Puchala, A. Patra, A. L. Goetsch, G. Animut, and T. Sahlu

Journal of Animal Science 85(Supplement 1):502. 2007

Forty-eight Angora goat wethers (16.7 ± 0.43 kg initial BW and 6 mo of age) were used in a 24-wk experiment to evaluate effects of level of feed intake on current and subsequent tissue (non-fiber) and mohair fiber growth. In Phase 1, 12 wk in length, different amounts of dehydrated alfalfa pellets were fed to provide ME according to NRC requirements adequate for tissue and mohair fiber growth (g/d) of 0 and 0 (0L), 15 and 1.5 (15L), 30 and 3.0 (30L), 45 and 4.5 (45L), 60 and 6.0 (60L), and 75 and 7.5 (75L), respectively. Alfalfa pellets were consumed ad libitum in Phase 2. Digestibility of OM was similar among treatments in both phases. In both phases ME intake (MEI) increased linearly (P < 0.05) with increasing level of DMI in Phase 1 (Phase 1: 5.40, 5.24, 6.00, 7.15, 7.89, and 8.04 MJ/d; Phase 2: 10.93, 11.00, 12.02, 13.50, 13.59, and 16.32 MJ/d for 0L, 15L, 30L, 45L, 60L, and 75L, respectively). Energy expenditure in Phase 1 increased linearly (P < 0.05) with increasing level of DMI (3.67, 3.87, 3.91, 4.18, and 5.20 MJ/d for 0L, 15L, 30L, 45L, 60L, and 75L, respectively) and was similar among treatments in Phase 2 (6.45 ñ 0.40 MJ/d). Tissue growth increased linearly (P < 0.05) with increasing DMI in Phase 1 (15.3, 30.9, 49.2, 58.9, 62.5, and 72.1 g/d) and was similar among treatments in Phase 2 (105.6, 108.3, 91.9, 81.9, 76.0, and 97.0 g/d for 0L, 15L, 30L, 45L, 60L, and 75L, respectively). Mohair fiber growth was similar among treatments in Phase 1 (6.6, 6.6, 6.0, 6.2, 7.8, and 7.0 g/d) and in Phase 2 (6.6, 6.8, 5.5, 6.1, 9.2, and 7.3 g/d for 0L, 15L, 30L, 45L, 60L, and 75L, respectively). Mohair diameter increased linearly (P < 0.05) with increasing DMI in Phase 1 (21.7, 21.8, 22.1, 23.4, 23.8, and 23.0 m) and in Phase 2 (25.4, 25.5, 26.0, 27.1, 27.0, and 27.1 m for 0L, 15L, 30L, 45L, 60L, and 75L, respectively). In conclusion, growing Angora goats partition nutrients to maintain mohair fiber growth with limited MEI and decrease ene rgy expenditure to lessen the ME requirement for maintenance, resulting in compensatory tissue growth upon realimentation.