Effects of pasture access regime on yield and composition of milk produced by Alpine goats

TitleEffects of pasture access regime on yield and composition of milk produced by Alpine goats
Publication TypeConference Proceedings
Year of Conference2012
AuthorsKeli, A, Goetsch, AL, Gipson, TA, Puchala, R, Zeng, S, Detweiler, GD, Tesfai, K
Conference NameXI International Conference on Goats

Thirty-two Alpine does (56 ± 1.6 kg initial BW, 2.1 ± 0.13 kg initial milk production , and 2.1 ± 0.20 parity) were used to evaluate effects of different pasture access regimes on milk production and composition, as well as other conditions such as forage intake, digestion, grazing behavior, energy utilization, and internal parasitism. The experiment began at 26 ± 2.5 days in milk and lasted 24 wk. Treatments were access to grass and (or) legume pasture from 0800 h, after the morning milking at 0700 h, to 1600 h (SET), continually (CG), the time of no dew (i.e., leaf surface moisture below a threshold level) until milking at 1600 h (ND-M), and the time of no dew until sunset (ND-D). When not on pasture does were housed in confinement in treatment groups. The SET, CG, and ND-M does were supplemented with 1.5% BW (DM) of concentrate (17% CP and 86% TDN) immediately after the 1600 h milking, whereas does on ND-D were supplemented at sunset. The ND-M and ND-D does were fed alfalfa hay when length of pasture access was less than 6 h, with the level based on length of pasture access. Milk yield was recorded daily and milk samples were collected every 2 wk. Milk yield and concentrations of protein, fat, lactose, total solids, and solids-non-fat were similar among treatments (P > 0.05). Treatment did not affect (P > 0.05) milk concentrations of lauric (C12:0; 3.8 ± 0.18), myristic (C14:0; 10.5 ± 0.30), palmitoleic (C16:1; 1.2 ± 0.06), linoleic (C18:2; 1.9 ± 0.54), or linolenic acids (C18:3; 0.2 ± 0.07). However, there were differences in levels of butyric (C4:0) (2.7, 2.5, 2.9, and 2.6%; SEM = 0.08), caprylic (C8:0) (2.7, 2.4, 2.9, and 2.7%; SEM = 0.10), capric (C10:0) (8.7, 7.6, 9.5, and 8,8%; SEM = 0.40), and palmitic acids (C16:0) (29.6, 29.3, 32.2, and 29.2%; SEM = 0.57), with a low value for CG in many instances. There were differences in concentrations of stearic (C18:0) (15.3, 17.0, 14.0, and 15.3%; SEM = 0.54) and oleic acids (C18:1) (23.0, 24.0, 20.3, and 23.4% for SET, CG, ND-M, and ND-D, respectively; SEM = 0.66) as well, with generally high levels for CG (P