Effect of water restriction and dietary sodium on nutrient metabolism in lambs

Twenty-four Hampshire X Suffolk wether lambs (40 kg) were used in 2 X 2 factorial arrangement of treatments to study the influence of water restriction and high levels of dietary Na on nutrient utilization. Lambs were offered either a normal Na diet (.20% Na) or a high Na diet (1.77% Na). Additionally, the lambs were offered either a normal quantity of water (previously determined voluntary intake of lambs fed normal Na levels) or were restricted to a water intake 80% of normal. Each lamb received 800 g/d of a hay-corn diet (77.5% fescue hay) with an additional 38 g of NaCl offered to lambs on high Na treatments. The complete experiment consisted of 14 d of adjustment and 7 d of total collection with blood and ruminal characteristics measured on the last day of the collection period. A high Na intake decreased (P less than .05) the apparent digestibility of neutral detergent fiber, but tended to increase the apparent absorption of Mg. Plasma urea N concentrations were not affected (P greater than .05) by level of Na or water intake. Plasma Na and K concentrations were not affected (P greater than .05) by treatment regimen. A high Na intake increased (P less than .05) plasma Mg concentrations at 6 h post-feeding with a normal level of water intake, but decreased (P less than .05) Mg concentrations at 6 h with restricted water intake. Ruminal ammonia N and K concentrations at 2 h post-feeding were decreased (P less than .05) by a high level of dietary Na. Ruminal Na concentration was not affected (P greater than .05) by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)