Effects of water supplementation with tryptophan and vitamin B or feeding hydrogenated fat on reducing hunger-induced drinking pre-slaughter in pigs

A current food safety challenge at pig slaughter plants comes with the presence of stomachs filled with liquid induced by hunger-related drinking in lairage. With the objective to reduce hunger-related excess drinking, 30 barrows were assigned to three treatments (10 pigs per treatment): (1) unsupplemented water or feed regimen (CONT), (2) L-Tryptophan (3 g L) and vitamin B6 (10 mg L) in the drinking water for 5d (TRP-B6), (3) hydrogenated fat (HF) supplemented at 10% in the diet for the last day of feeding before pre-slaughter fasting. As compared with CONT, neither TRP-B6 nor HF supplementation influenced behaviour in lairage and water intake at anytime over the pre-slaughter fasting period as reflected on stomach weight and its liquid content at slaughter (P>0.10). However, in HF-fed pigs plasma non-esterified fatty acids concentrations tended to be lower (P=0.09) while carcass yield was higher (P>0.04) than CONT pigs. It appears, therefore, that neither drinking water supplementation with TRP-B6 for 5 d nor feeding HF the last day before slaughter can be recommended strategies to limit excess water drinking prior to slaughter and liquid stomach content at slaughter. However, dietary HF supplementation the last day before slaughter may attenuate the effects of fasting on body energy reserves and improve carcass yield.