PSVIII-B-9 - Effects of Level and Type of Fiber Sources on Feed Intake, Average Daily Gain, Digestion, and Milk Production by Alpine Goats

Abstract: Thirty Alpine does and 32 doelings, averaging 45±1.5 days-in-milk, were used in a study with four 4-wk periods to determine effects of level and type of neutral detergent fiber (NDF) sources on feed intake, average daily gain (ADG), digestion, and milk production. The 60C, 50C, 50W20S, and 40W30S diets were 60, 50, 30, and 30% concentrate and 40, 50, 50, and 40% forage, with 20 and 30% soybean hulls in 50W20S and 40W30S, respectively. Diet NDF concentration was 36, 39, 52, and 52% for 60C, 50C, 50W20S, and 40W30S, respectively. Overall dry matter intake (DMI) was highest (P< 0.05) for 60C and 50C, but differences were greater in periods 1 (2.96, 2.76, 2.06, and 2.27) and 2 (2.67, 2.76, 2.18, and 2.35) than in periods 3 (2.60, 2.55, 2.04, and 2.28) and 4 (2.38, 2.32, 2.07, and 2.13 kg/day for 60C, 50C, 50W20S, and 40W30S, respectively; SEM=0.142). There was a three-way interaction in ADG, with values of 31, 32, -22, and -10 for doelings (SEM=15.1) and 8, 0, -22, and -11 g for does consuming 60C, 50C, 50W20S, and 40W30S, respectively (SEM=18.6). Digestion of organic matter after period 4 was 71.3, 71.3, 80.1, and 80.7% (SEM=0.95) and of NDF was 44.7, 48.8, 73.7, and 75.8% for 60C, 50C, 50W20S, and 40W30S, respectively (SEM=1.56). Milk fat concentration was highest (P< 0.05) for 40W30S (2.81, 2.92, 2.85, and 3.13%; SEM=0.051), with raw milk yield similar among treatments (3.10, 2.87, 2.64, and 2.79 kg/day 60C, 50C, 50W20S, and 40W30S, respectively; SEM=0.144). Average milk energy yield was 7.61, 7.20, 6.48, and 7.20 MJ/day (SEM=0.354) and 2.85, 2.90, 3.11, and 3.18 MJ/kg DMI for 60C, 50C, 50W20S, and 40W30S, respectively (SEM=0.130). In conclusion, high-NDF diets may limit feed intake more in mid- than late lactation and restrict ADG of doelings; however, perhaps because of differences in digestibility, they did not significantly affect milk energy yield.