PSX-8 Effects of dietary concentrate level and limited feed access on feed intake and performance by lactating Alpine dairy goats

The objective was to determine if effects of different limited feed access treatments on performance by lactating Alpine dairy goats vary with dietary concentrate level. Primiparous (29; 55.2±0.8 kg BW) and multiparous Alpine goats (29; 70.2±1.06 kg) were used in a 24-wk study of 3 8-wk phases beginning at 7.1±0.37 d after kidding. Diets of 40 or 60% concentrate (40C and 60C, respectively) were offered free choice in Calan gate feeders, with access continuously (CON), for 8 h between morning and afternoon milkings (DAY), or for 2 h after each milking (FRH). Although there were many interactions involving phase, ADG during the entire study was greater for CON vs. FRH (P < 0.05; -20, -41, and -61 g for CON, DAY, and FRH, respectively; SEM = 8.6). Intake of DM also was greater for CON than for FRH (P < 0.05; 2.17, 2.03, 2.01, 2.29, 2.07, and 1.80 kg/d for 40C-CON, 40C-DAY, 40C-FRH, 60C-CON, 60C-DAY, and 60C-FRH, respectively; SEM=0.093). There were interactions (P < 0.02) between concentrate level and access treatment in milk yield (2.55, 2.41, 2.61, 3.21, 2.66, and 2.27 kg/d; SEM=0.103) and protein concentration (2.65, 2.55, 2.60, 2.67, 2.70, and 2.49%; SEM = 0.042), and milk fat concentration was greatest among treatments (P < 0.05) for FRH (2.79, 2.77, 3.18, 2.86, 2.89, and 3.02% for 40C-CON, 40C-DAY, 40C-FRH, 60C-CON, 60C-DAY, and 60C-FRH, respectively; SEM=0.103). As a consequence, milk energy yield was 6.14, 5.70, 6.67, 7.83, 6.58, and 5.61 MJ/d (SEM=0.251) and the ratio of milk energy to DMI was 3.01, 2.87, 3.37, 3.47, 3.28, and 3.18 MJ/kg for 40C-CON, 40C-DAY, 40C-FRH, 60C-CON, 60C-DAY, and 60C-FRH, respectively; SEM=0.123). Overall, limited feeder access treatments did not improve performance and, in fact, the shortest access treatment increased BW loss; however, efficiency of feed DM usage for milk energy yield was not adversely impacted.