Abstract
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.
The effect of number of lactation and concentrate level on feed intake and performance of dairy cows
