An investigation into the effect of tryptophan on tail chewing behaviour of growing pigs

Abstract

Previous work (McIntyre and Edwards, 2001) revealed a significant correlation between plasma tryptophan (TRP) concentration and blood preference scores when pigs were fed a low CP diet. Increasing dietary TRP in rats causes increases in plasma and brain TRP, and brain serotonin concentration (Fernstrom and Wurtman, 1971), which appear to be highly localised to serotonin-containing neurones that may monitor the metabolic state and control behaviour. Uptake of TRP at the blood-brain barrier and serotonin level may also be increased by a higher TRP: LNAA (large neutral amino acids) ratio and level of dietary carbohydrate. This study aimed to determine if pigs fed diets differing in TRP and TRP: LNAA ratios differed in their behaviour or in their preference for blood during a model tail test.