INTAKE, DIGESTIBILITY, RUMEN METABOLISM AND GROWTH PERFORMANCE OF GOAT KIDS RAISED UNDER DIFFERENT PRODUCTION SYSTEMS

Abstract

Forty-five wether goat kids (BW of 21.76 + 0.76) were randomly assigned to one of three production systems for 14 weeks to evaluate intake, digestibility and goat performance. Production systems were: 1) feedlot (FL), housed in individual pens and fed 40% protein pellets, 40% soybean hulls and 20% bermudagrass hay; 2) grazing continuously on 1 hectare bahiagrass pasture (BP) supplemented daily with 150 g of protein pellets/hd; and 3) browsing rotationally on 4, 0.5 hectare mimosa (MB) supplemented daily with 100 g cracked corn/hd. Body weights were recorded every two weeks. Feed intake and digestibility were measured on eight goats from each treatment groups. Goats were fitted with canvas fecal collection bags, allowed for 3 days of adjustments followed by 5 days of fecal collection. Feces, feed offered, pasture and browse samples were analyzed for acid insoluble ash to determine digestibility and predict intake. Rumen fluid and blood samples were collected to measure volatile fatty acids and blood urea nitrogen (BUN). Total feed and medication costs also were recorded. Goats on FL system gained faster (P < 0.05) and reached highest (P < 0.05) final BW in less days as compared with MB and BP, with BP goats having the lowest (P < 0.05) growth performance. Estimated DMI and digestibility for goats on FL system was highest (P < 0.05) when compared to other systems, with goats on MB having the least (P < 0.05) intake and digestibility. However, gain efficiency was highest (P < 0.05) for goats on MB when compared to others, with goats on BP having the least (P < 0.05) gain efficiency. Rumen pH was lowest (P < 0.05) for FL goats and highest (P < 0.05) for MB goats. Molar proportion of acetate was lowest (P < 0.05), and isobutyrate and isovalerate were highest (P < 0.05) for MB goats with no change (P > 0.10) in butyrate and valerate. However, acetate: propionate was lower (P < 0.05) for FL goats. Blood urea nitrogen was higher (P < 0.05) for MB goats before feeding, one, or two hours after feeding. Goats on FL and BP system had similar (P > 0.10) BUN. Numerically, browse system was most cost effective and bahaigrass pasture was most expensive in terms of animal production.