Behaviour and physiology of sheep exposed to ammonia at a similar concentration to those experienced by sheep during export by sea

Abstract

Ammonia accumulates in livestock accommodation, which inflames mucosal tissue to cause coughing, sneezing and lacrimation and adversely affects feed intake. We aimed to find out why feed intake is reduced for sheep in ammonia conditions typical of live export by measuring nutritional behaviour and stress levels. Twelve sheep were randomly allocated to Ammonia or Control treatments in a changeover design with three 2-week periods. Ammonia exposure reduced feed intake (P = 0.005) and defecation time (P = 0.05) and slowed the rates of eating hay (P = 0.007), masticating alfalfa pellets (P = 0.00) and rumination chewing (P = 0.01). It also lengthened the pauses between swallowing and regurgitation during rumination (P = 0.002), increased faecal corticosterone metabolites concentration on day 6 (P = 0.04), increased respiratory rate (P = 0.00), and reduced yawning (P = 0.02). The increase in faecal corticosterone metabolites concentration in ammonia exposed sheep was not correlated with the reduction in feed intake. The results suggest that although sheep exposed to ammonia typical of a live export shipment are stressed, this is not the reason for reduction in feed intake. They may have an irritation in the buccal cavity which retards nutritional behaviour, and causes shallow rapid breathing to minimise irritation to the lungs.