Observations on the adaptation by sheep to saline drinking water

Abstract

The extent of adaptation by sheep and rumen micro-organisms to saline drinking water was investigated in two experiments. In the first experiment, eleven sheep were introduced suddenly to drinking water containing 2 per cent NaCl. Food intakes fell sharply for three days, but then increased again, and by five to seven days reached a stable level 160 g below the food intake on fresh water. In the second experiment, rumen liquor for in vitro digestion studies was taken from sheep conditioned to saline drinking water (2 per cent NaCl) and from sheep with no experience of saline drinking water. The amount of dry-matter (ryegrass) digested decreased with increasing concentration of the medium, but there was no evidence of adaptation by the rumen micro-organisms to this increased concentration. When the concentration was increased by the addition of NaCl alone, the decrease in amount digested was less than when the concentration of all ions was increased.