PSIX-19 Effects of natural sources of brackish water on milk yield and composition of Alpine dairy goats.

Abstract This study aimed to evaluate the effects of various United States Geological Survey (USGS) water classifications on the milk yield and composition of lactating Alpine dairy goats. The experiment involved 32 Alpine dairy goats over a six-week period. Drinking water treatments were categorized as fresh water (FRW), West Pasture brackish water (BRW), USGS group 2 water (GR-2), USGS group 3 water (GR-3), and an unclassified water group (G-UC). The total dissolved solids (TDS) content for these treatments measured 383±119, 6385±356, 3099±227, 5410±125, and 2567±165 g/L of water, respectively. Goats were fed a total mixed ration comprising 50% forage and 50% concentrate, delivered at 4% body weight on an air-dry basis. Daily milk production was recorded, and milk samples were collected during both morning and evening milkings at weeks 0, 3, and 6. Milk yield was similar among water treatments (P=0.180, SEM=0.238), with averages values of 2.4, 2.4, 1.88, 2.16, and 1.74 kg/day for FRW, BRW, GR-2, GR-3, and G-UC, respectively. However, milk yield varied significantly over time (P< 0.001; SEM=0.122), declining in weeks 5 and 6 compared to earlier weeks. Weekly averages were 2.31, 2.23, 2.21, 2.21, 2.14, 1.88, and 1.81 kg/day for weeks 0, 1, 2, 3, 4, 5, and 6, respectively. Milk composition parameters, including butterfat, true protein and lactose levels, were unaffected by water treatments or time. Butterfat percentages were 3.33, 3.29, 3.87, 4.30, and 3.5% for FRW, BRW, GR-2, GR-3, and G-UC, respectively; and 3.67, 3.76, and 3.52% for week 0, 3, and 6, respectively. True protein percentages were 2.64, 2.67, 2.60, 2.69, and 2.76% for FRW, BRW, GR-2, GR-3, and G-UC, respectively (P=0.844); and 2.65, 2.59, and 2.78% for week 0, 3, and 6, respectively. Lactose levels of milk samples were also similar among water treatments (4.41, 4.35, 4.54, 4.43, and 4.53%, SEM = 0.062 for FRW, BRW, GR-2, GR-3, and G-UC, respectively); and 4.48, 4.48, and 4.40% for week 0, 3, and 6, respectively. Milk urea levels, however, exhibited a trend toward variation among water treatments (P=0.055), with levels of 18.9, 18.4, 20.8, 23.9, and 20.8 mg/dl for FRW, BRW, GR-2, GR-3, and G-UC, respectively. Additionally, milk urea levels increased over time, averaging 18.96, 20.39, and 22.38 mg/dL at weeks 0, 3, and 6, respectively (P=0.025; SEM=0.917). In conclusion, drinking water treatments had no significant impact on milk yield or most composition parameters. This suggests that Alpine dairy goats exhibit resilience when consuming brackish water from West Pasture, USGS group 2, group 3, and unclassified sources.