Sodium chloride supplements increase the salt appetite and reduce stereotypies in confined cattle

The influence of prior exposure to high salt diets on the salt appetite and the exhibition of stereotyped behaviour patterns was investigated with ind ividually penned calves and tethered dairy cows. In the first experiment on e half of a group of 12 calves received concentrates with the sodium conten t increased from 4 to 9 g/kg by the addition of NaCl up to weaning at 6 wee ks, the other half had no supplementary NaCl added to the concentrates. Add ing the NaCl increased the food intake of the calves, the time spent rumina ting and live weight. Stereotyped behaviour patterns, such as self-grooming , licking the pen or buckets and ear sucking were reduced by adding NaCl. C alves were tested for their salt preference at 6 months of age by adding va rying quantities of NaCl to silage. Exposing calves to supplementary NaCl i n the concentrate pre-weaning increased the preferred sodium concentration of silage from 3 to 9 g/kg dry matter (DM). In the second experiment 36 tet hered dairy cows received either a restricted concentrate and forage diet w ith a mean dietary sodium concentration of 2 g/kg DM, or the same diet but with the sodium content increased to either 7 or 12 g/kg DM by adding NaCl to the concentrates. There was no effect of NaCl on feeding or ruminating b ehaviour but the total amount of stereotyped behaviour, including mouthing or rubbing the tethering chain or bars, self-grooming and nosing or pawing the ground, decreased with increasing salt in the diet. It is concluded tha t increasing the sodium content of the diet of young calves from 4 to 9 g/k g increased their subsequent salt appetite and that increasing the salt con tent of the diet of calves or cows in restricted housing conditions can red uce the amount of stereotyped oral behaviour.