Effect of moderate to high salinity in drinking water and protein supplementation on water and feed intake, digestion, energy metabolism, blood constituents, and mineral balances in yearling meat goats

The effect of saline drinking water and protein supplementation level (SL) on nutrient utilization, ruminal fermentation, blood biochemical responses, and mineral balances were determined in yearling meat goats. Eighteen Boer and 18 Spanish wethers consumed straw ad libitum supplemented with soybean meal dry matter (DM) at 0.14 or 0.28 % body weight (LP and HP, respectively) during two 4-wk phases. Phase-1 water treatments were fresh water (FW) containing 233 mg/l total dissolved salts (TDS) and FW with approximately 10,000 and 15,000 mg/l TDS via sodium chloride addition (MS and HS, respectively). The added TDS level for HS was 20,000 mg/l TDS in phase 2. Water intake increased (P < 0.05) in the HS-goats. However, feed intake, nutrient digestibility, total volatile fatty acid concentration, and molar proportions of major fatty acids were not affected by (P > 0.05) by WT and any interactions with WT. Plasma osmolality decreased (P < 0.05) in the HS group during phase 1 and was influenced by the interaction between WT and SL in phase 2, accompanied by reduced plasma sodium and creatinine concentrations in the HS group. Oxygen saturation of hemoglobin decreased in Boer goats consuming HS water, but not in Spanish goats in phase 1. Plasma bicarbonate levels were decreased (P < 0.05) by WT for Boer goats in both SL and for Spanish goats in low SL. Mineral metabolism was influenced by WT and SL; saline water intake increased (P < 0.05) urinary excretion of sodium, calcium, iron, and zinc, with effects varying by SL and breed. In conclusion, while saline water intake has minimal impact on nutrient utilization and ruminal fermentation, it affected blood acid-base balance and oxygen-carrying capacity, with some differences between Boer and Spanish goats in their physiological adaptation to salinity. Protein supplementation helps mitigate some of the negative effects of saline water.