Effects of drinking water salinity on water and feed intake, nutrient utilization, physiological conditions, and mineral balances in yearling meat goats with different protein levels

The objective was to determine if effects of the level of salinity in drinking water for yearling meat goat wethers consuming low-quality roughage are influenced by level of protein supplementation and breed. The treatment arrangement was a 2 × 2 × 3 factorial, with two breeds, two supplementation levels (SL) of soybean meal (SBM), and three water treatments with goats allocated using a completely randomized design. Eighteen Boer (initial body weight: 37.9 ± 1.12 kg, age: 1.15 ± 0.009 years) and 18 Spanish goats (body weight: 33.5 ± 0.66 kg, age: 1.16 ± 0.008 years) consumed wheat straw ad libitum over two phases of four weeks each. Soybean meal was supplemented at 0.14 or 0.28% body weight (dry matter basis; Low and High, respectively) and water treatments were fresh alone (240 mg/kg total dissolved salts) or with sodium chloride added at approximately 5000 or 10,000 mg/L (FW, MS, and HS, respectively). Body weight change, total feed intake, and digestibility of nutrients were not influenced by level of protein supplementation, water treatment (P > 0.05), or their interactions. Water intake ranked (P < 0.05) FW < MS < HS (1093, 1295, and 1541 g/day; SEM = 66.6). There was an interaction (P < 0.05) in total dry matter intake between breed and water treatment because of a relatively low value for Spanish goats drinking FW (821, 733, and 811 for Boer and 636, 781, and 796 g/day for Spanish consuming FW, MS, and HS, respectively; SEM = 38.0). Ruminal total volatile fatty acid concentration and proportions of acetate, propionate, and butyrate were not affected (P > 0.05) by water treatment and its interaction with breed or protein supplement treatment. Most of the blood and serum constituents (except creatinine, urea nitrogen, anion gap, and bicarbonate) were not affected (P > 0.05) by any factor. Water treatment affected (P < 0.05) fecal and urinary excretion of several minerals including calcium, phosphorus, sodium, magnesium, sulfur, zinc, and manganese. However, there were few minimal interactions of water treatment involving breed or supplement treatment. In conclusion, these yearling meat goats displayed considerable tolerance to saline drinking water with sodium chloride additions of up to 10,000 mg/kg, without consistent breed differences. Additionally, the effects of protein supplementation did not markedly vary among the different water treatments or between the goat breeds.