The effect of dietary bentonite on post-weaning diarrhoea, growth performance and blood parameters of weaned piglets

• Bentonite had no antibacterial activity on ETEC O149:F4:LT in vitro.
• Dietary bentonite did not reduce post-weaning diarrhoea and mortality of piglets.
• Protective effect of bentonite on the small intestinal mucosa was noted.
• Bentonite diet did not affect the post-weaning growth rate of piglets.
• No adverse effects of bentonite on the serum chemistry of piglets were recorded.

The aim of this study was to investigate the effects of dietary supplementation of weaned piglets with natural bentonite on post-weaning diarrhoea (PWD), intestinal colonization by enterotoxigenic Escherichia coli (ETEC) and intestinal histopathology, growth performance, and haematological and serum biochemical parameters. The piglets in our study were obtained from a traditional farm with a high prevalence of PWD. The effects of dietary bentonite were tested on 50 weaned piglets in two trials. Piglets were allocated to two dietary groups, control and bentonite, receiving a basal diet with or without bentonite supplementation at levels of 1% and 2% for 21 days. In vitro testing of antibacterial activity of bentonite against ETEC O149:F4:LT showed that it had no ability to reduce bacterial plate counts. Dietary bentonite has not been effective in reducing the occurrence and duration of diarrhoea or mortality rates, although faecal ETEC shedding decreased (P = 0.004) in bentonite fed piglets. Histopathological examinations of the intestines demonstrated that 2% bentonite exerted a protective effect on the small intestinal mucosa, the inflammation of which was milder. Also, a beneficial effect on regenerative processes following intestinal infections was observed. A significantly lower leukocyte count (P = 0.048) in peripheral blood indicated that the infection in bentonite-fed piglets was less severe. Exposure of piglets to bentonite did not significantly affect their post-weaning growth performance. The addition of bentonite to diet had no adverse effect on biochemical blood parameters in piglets. The present study shows that the use of natural untreated bentonite as a feed additive for weaned piglets can be considered safe, but its final efficacy in preventing the occurrence and severity of PWD is low.