Moderate levels of dietary sheep milk powder reduce experimentally induced colonic inflammation in rats

Abstract

Anecdotal evidence suggests that sheep milk may be more beneficial than cow milk for people with intestinal health problems; however, there are no published reports on the effects of sheep milk on intestinal function. Our hypothesis was that sheep milk powder can reduce the severity of colonic inflammation in rats with dextran sodium sulfate (DSS)-induced colitis. A preliminary experiment investigated the palatability of sheep milk powder in the diet of 5-week-old rats with (n = 8) or without (n = 8) DSS-induced colitis. Increasing sheep milk powder from 11 to 56% in the diet had no effect (P > 0.05) on food intake, showing that rats readily eat low and high levels of sheep milk powder in the diet, with or without DSS. Experiment 2 investigated the effects of moderate levels of sheep milk powder (11%) in rat diet on colon morphology, colonic biochemical markers of intestinal function, and caecal short-chain fatty acid concentrations, with (n = 8) or without (n = 8) DSS-induced colitis. Colon total histological injury scores decreased and caecal concentrations of butyric and propionic acids were increased (P < 0.05) in DSS rats fed moderate (11%) dietary levels of sheep milk powder. Experiment 3 investigated the effects of high levels (56%) of sheep milk powder in rat diet on colonic markers of intestinal inflammation, and caecal microbial populations, with (n = 11) or without (n = 8) DSS-induced colitis. Sheep milk powder at 56% of the diet had no effect on colonic biochemical markers of intestinal health, or on caecal short-chain fatty acid concentrations. However, the caecal digesta concentrations of beneficial microbial populations (lactobacilli, bifidobacteria and clostridia) were increased (P < 0.05) and the concentrations of potentially harmful bacteria (coliforms) were decreased (P < 0.05). These results suggest the benefits of moderate levels of sheep milk during DSS-induced colonic inflammation may be due to alterations in the caecal microbiota composition, and further investigation into its health benefits are warranted.