The effect of graded levels of melatonin on performance and gastric ulcers in pigs

Graded concentrations of dietary melatonin were fed to examine the effects on performance and gastric ulcers in pigs. Four levels of melatonin, 0, 2.5, 5, and 10 mg kg(-1), were fed in a finely ground, corn-wheat based diet (578 +/- 1.89 mu m), designed to induce gastric ulcers, to 64 Yorkshire barrows and gilts between 22.2 +/- 2.0 and 102.5 +/- 4.3 kg. At postmortem, ulcers were scored from 0 (no ulcer) to 3 (severe ulcer). Volume, percent moisture, pH; and bile acid concentration of the stomach digesta were determined. Melatonin supplementation was associated with a decreasing severity of ulcers (P < 0.05). There were no differences in average daily gain between melatonin treatments; although 10 mg kg(-1) diet caused a reduction in feed intake. Bile acid concentration in the stomach digesta was highest in pigs receiving the control diet without melatonin (P < 0.05) and was increased with increasing ulcer severity (P < 0.05).