Low sanitary housing conditions increase protein fermentation in piglets but do not aggravate the effects of protein fermentation on intestinal health

Abstract

Protein fermentation has been identified as a risk factor for the occurrence of post-weaning diarrhea. Associations between low protein digestion – provoking protein fermentation - and low sanitary housing conditions suggest that protein fermentation, low sanitary conditions, and post-weaning diarrhea are interlinked.To this end, an experiment (2×2 factorial treatment arrangement) was performed with 160 weaned female piglets (TN70 х Tempo) divided over 5 batches (4 piglets per pen, 2 pens/treatment/batch). The piglets were kept under high (HSC) or low (LSC) sanitary conditions and were fed a diet low (LiP) or high (HiP) in indigestible protein for 14 days. Fecal consistency was scored daily per piglet and after one week, digesta samples were collected to analyze protein digestibility, colonic flow of protein-derived metabolites, and digesta mean retention time in 2 piglets per pen. Furthermore, we measured intestinal permeability for Fluorescein isothiocyanate-dextran (FITC, 4 kDa) and Tetramethylrhodamine isothiocyanate–dextran (TRITC, 40 kDa), and jejunal absorption capacity for lysine, methionine, and glucose, using the everted gut sac technique.Piglets kept under LSC had 9% units lower apparent total tract protein digestibility than piglets kept under HSC (P < 0.001), mainly explained by 7% units lower apparent ileal protein digestibility in LSC piglets (P < 0.001). Since no relevant correlations were observed between digesta mean retention time and ileal N digestibility and jejunal absorption capacity did not differ between treatment groups, these factors were excluded as underlying causes. The colonic flow of protein-derived metabolites was higher for LSC piglets than for HSC piglets (NH3: +31%, BCFA: +40%, P < 0.001), and higher for HiP piglets than for LiP piglets (NH3: +76%, BCFA: +42% for LSC, +25% for HSC, P < 0.001, SC х Diet P < 0.05). Colonic N disappearance was 5.5% units higher for HiP piglets than for LiP piglets (P < 0.01), but was not affected by SC. Fecal consistency scores were reduced for both HiP (−1.5, P < 0.001) and LSC (−0.5, P < 0.001) piglets compared with LiP and HSC, but no SC х diet interaction was observed. Jejunal permeability was slightly increased for HiP piglets (P < 0.05). No negative effects of feeding HiP on colonic permeability were observed.Low sanitary conditions decrease both ileal and fecal protein digestion to a similar extent and stimulate colonic protein fermentation. It is unlikely that digesta transport or jejunal absorption rates are causal to this effect. There are no indications that housing under low sanitary conditions aggravates the effects of protein fermentation on intestinal health.