1708 Effects of pasture access regimen on grazing behavior and energy utilization by Alpine goats.

Twenty-eight Alpine goats (initially 53.2 ± 1.80 kg BW and 26 ± 2.5 days in milk; 11 primiparous) were used to evaluate effects of different pasture access regimens on grazing behavior and energy utilization in a 16-wk experiment with 4-wk periods. Treatments were access to grass and(or) legume pasture from 0800 h, after the morning milking at 0700 h, to 1600 h (SET); continually other than during milking (CG); from the time of no moisture on leaf surfaces until milking at 1600 h (ND-M); and from the time of no leaf surface moisture until sunset (ND-D). The SET, CG, and ND-M goats were supplemented with 1.5% BW (DM) of concentrate immediately after the afternoon milking, whereas ND-D goats were supplemented at sunset. The ND-M and ND-D goats were fed alfalfa hay when length of pasture access was less than 6 h, with the level based on length of pasture access. Digestibility of OM determined each period from fecal DM and AIA in feedstuffs and feces was 77.0, 79.1, 81.3, and 77.8%, respectively (SE = 1.46), and ADG was similar among treatments (−12, −15, 2, and −6 g for CG, ND-D, ND-M, and SET, respectively; SE = 10.9). Neither fecal egg count nor FAMACHA score was affected by treatment (P > 0.05). Based on data from GPS collars and leg activity monitors, treatment affected (P < 0.05) time spent grazing (7.43, 6.93, 5.86, and 6.18 h, respectively; SE = 0.343), resting while lying (8.48, 8.82, 10.63, and 9.11 h, respectively; SE = 0.480) and standing (6.33, 7.29, 6.85, and 7.82 h, respectively; SE = 0.338), and walking (1.75, 0.95, 0.66, and 0.90 h for CG, ND-D, ND-M, and SET, respectively; SE = 0.093). Intake of ME was similar among regimens (P > 0.05; 26.73, 24.54, 26.25, and 22.37 MJ/d, respectively; SE = 1.522), although heat energy determined from heart rate and heat energy per heart beat was greatest for CG (P < 0.05; 14.41, 13.11, 12.90, and 13.03 MJ/d for CG, ND-D, ND-M, and SET, respectively; SE = 0.392). Milk energy yield was similar among treatments (5.41, 5.06, 5.34, and 5.55 MJ/d, respectively; SE = 0.35), but milk energy:ME intake was greatest (P < 0.05) for SET (0.228, 0.219, 0.220, and 0.275 for CG, ND-D, ND-M, and SET, respectively; SE = 0.0104). In conclusion, restricting time of pasture access from the morning to afternoon milking appeared to favorably affect efficiency of energy utilization for lactation, not relating to internal parasitism, but rather by limiting time spent and heat energy associated with grazing.