Studies on salt tolerance of sheep. I. The tolerance of sheep for sodium chloride in the drinking water

Abstract

Four groups, each of six sheep, were fed in pens for 15 months on an adequate diet of chaffed lucerne and wheaten hays. One group was offered rain-water to drink, whereas the others were offered similar water to which sufficient sodium chloride had been added to give concentrations of 1.0, 1.5, or 2.0 per cent. sodium chloride. The intake of water increased with concentration of sodium chloride, the mean daily intakes for the entire experiment being 2.0, 3.0, 4.4, and 3.0 1. for the groups whose water contained 0, 1.0, 1.5, and 2.0 per cent. sodium chloride, respectively. It also increased in all groups with temperature, being 50-70 per cent. higher in the hottest months than in the coldest months. The intake of sodium chloride by some sheep was very high; four of them consumed over 115 g (0.25 lb) daily for more than half the experiment, and 170-230 g daily for periods of 1-10 weeks. A concentration of 1.0 per cent. sodium chloride in the drinking water had no adverse effects on the sheep, but 1.5 per cent. TI-as detrimental to a small proportion and 2.0 per cent. was detrimental to all of the sheep. There was a decline in food consumption and body weight of the affected ammals, and several receiving 2.0 per cent. sodium chloride became very emaciated and weak and two were killed in extrentis. The only other obvious sign was an occasional diarrhoea which occurred in most of the sheep receiving 2.0 per cent. sodium chloride. Sodium chloride in the drinking water had no effect on the concentration of sodium, potassium, calcium, or magnesium in the blood plasma. It did, however, affect the chloride concentration; this was significantly higher, throughout the experiment, in the group which received water containing 2.0 per cent. sodium chloride.