PS9-21. Impacts of Saline Water on Intake and Milk Production in Alpine Goats.

Abstract This study examined how different United States Geological Survey (USGS) water classifications affect feed intake, water consumption, milk yield, and milk composition in lactating Alpine dairy goats. Thirty-two goats (61.2 ± 7.9 kg body weight) were assigned to one of five drinking water sources for six weeks: fresh water (FRW), West Pasture brackish water (BRW), USGS group 2 (GR-2), USGS group 3 (GR-3), and an unclassified groundwater source (G-UC). Total dissolved solids (TDS) concentrations were 383 ± 119, 6385 ± 356, 3099 ± 227, 5410 ± 125, and 2567 ± 165 mg/L for FRW, BRW, GR-2, GR-3, and G-UC, respectively. All goats were fed a total mixed ration containing 18.9% crude protein. Dry matter (DM), crude protein, and organic matter intakes were not affected by water treatment (P > 0.05), with DM intake ranging from 2.16 to 2.38 kg/day. Water consumption also remained consistent across treatments (P = 0.424), averaging 6.44–8.17 kg/day. Milk production differed significantly among treatments (P = 0.038). Goats consuming BRW produced more milk than those receiving GR 2, GR 3, or G-UC, while FRW goats had intermediate yields. Average milk production ranged from 1.79 to 2.69 kg/day across water treatments. Despite differences in yield, milk composition, including butterfat, protein, urea nitrogen, and lactose, did not vary among treatments (P > 0.05). Butterfat ranged from 3.33–4.12%, protein from 2.54–2.76%, urea from 18.4–22.5 mg/dL, and lactose from 4.35–4.54%. Cheese yield was also unaffected (P = 0.846), ranging from approximately 0.68 to 0.98 lb/gal. During the digestibility phase, water source had no effect (P > 0.05) on nutrient intake, digested nutrient intake, or apparent digestibility. Water intake, urinary water loss, and water retention were likewise unaffected, with intake ranging from 3.99 to 6.11 kg/day, urinary losses from 1.72 to 2.41 kg/day, and retained water from 1.62 to 2.88 kg/day. Nutrient intake varied over time (P < 0.05), peaking during weeks 0–3 (2.4–2.5 kg/day) before declining in weeks 4 and 6. Water consumption remained stable (P = 0.115), averaging 6.6–8.6 kg/day. Milk yield declined significantly over time (P < 0.001), decreasing from 2.34 kg/day at week 0 to 1.55 kg/day at week 6, while milk composition and cheese yield remained stable. Overall, intake, water consumption, milk yield, milk composition and cheese yield remained within normal ranges, indicating that goats tolerated the salinity levels without adverse effects. Notably, goats consuming BRW produced the highest milk yield despite its high TDS, suggesting mineral composition may be more important than TDS alone. These results show that short-term exposure to moderate saline groundwater does not impair performance or cheese yield and support the use of Alpine goats in semi-arid regions where saline water is common.