This study was conducted to evaluate the effect of plant polyphenols (PP) on antioxidant activity in weaned piglets. First, a uniform design, one optimising an experimental technique that can rationally arrange the concentrations of mixture components, was used to obtain the best PP mixture of apple, grape seed, green tea and olive leaf polyphenols based on in vitro antioxidant capacity and inhibitory action on bacterial growth. Second, the optimised PP mixture was tested in vivo with an efficacy trial on piglets. The optimal effects of the mix were observed in vitro when apple, grape seed, green tea, olive leaf polyphenols and a carrier (silicon dioxide) accounted for 16.5, 27.5, 30, 2.5 and 23.5%, respectively, of the mixture. Forty-eight weaned piglets were randomly allocated to two dietary treatments (6 replicates of 4 piglets each per treatment) and fed a control diet (CTR) or CTR supplemented with 0.1% of the optimised PP mixture. Dietary PP did not affect growth performance compared to the CTR group. Plasma total protein, urea nitrogen and lysozyme content were not affected by dietary treatment. No differences of E. coli or Clostridia counts in the faeces and caecum content between the CTR and PP groups were observed. A reduced malondialdehyde concentration in the PP group was observed on day 21 compared to the CTR group (P=0.02). In conclusion, the prepared PP mixture has the potential to improve plasma antioxidant activity.

The present study evaluated the effects of a novel plant extract (PE) product (Grazix TM ) on the performance and gut health of weaned piglets challenged with Escherichia coli. The PE was a standardised mixture of green tea leaves (Camellia sinensis) and pomegranate fruit (Punica granatum) obtained by using the LiveXtract TM process. A total of 144 piglets were weaned at 24 days and allocated to 8 for a 35-day experiment with a 2 × 2 × 2 factorial design comparing different treatments (water without product (CT) or 8 μl/kg per day PE in drinking water (PE)), feeding regimens (ad libitum (AD) or restricted (RE)) and oral E. coli challenges on day 9 (sham (− ) or infected ( + )). There were six pens per group with three piglets per pen. On day 35, 24 of the RE feeding piglets were slaughtered. It was found that PE supplementation increased the average daily gain (ADG) from day 28 to day 35 ( P = 0.03) and increased the gain to feed ratio (G : F) from day 7 to day 14 ( P = 0.02). RE feeding led to lower feed intake in piglets during the 1 st week ( P < 0.01), 2 nd week ( P = 0.06), 3 rd week ( P = 0.05), and throughout the course of the overall study period ( P = 0.05). E. coli challenge decreased the ADG and G : F ratio from day 7 to day 14 ( P = 0.08 and < 0.01, respectively) and increased the faecal score (higher values indicate more severe diarrhoea) on days 14, 21, 28 and 35 ( P < 0.01). PE supplementation decreased the faecal score in the challenged piglets during the 1 st week post-challenge ( P < 0.01). E. coli challenge increased the faecal E. coli level on day 14 ( P = 0.03) and increased the Enterobacteriaceae level on day 35 ( P < 0.01). Reduced faecal E. coli was observed on days 14 and 35 ( P = 0.05 and 0.02, respectively), and reduced Enterobacteriaceae ( P < 0.01) was found on day 35 in the PE animals. RE feeding increased the faecal Lactobacillus, Enterobacteriaceae and E. coli levels on day 35 ( P = 0.02, < 0.01 and < 0.01, respectively). These results suggest that PE supplementation may improve the gut health status of post-weaning piglets and counteract some of the negative effects that occur when piglets are challenged with E. coli.Keywords: Escherichia coli, gut health, performance, piglet, plant extract ImplicationsThis study investigated the effects of a novel plant extract product that was added to the drinking water for weaned piglets. Different feeding regimens were tested, and the effects of the extract on growth performance, gut health and protection against Escherichia coli challenge were observed. The results showed that the plant extract may represent a useful additive for improving gut health and microbial ecology and reducing the severity of an E. coli challenge. The results may have a significant impact on nutritional management in conventional farms. Use of the plant extract could enable piglets to better withstand the infections that are often associated with weaning.

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