Long-term intake of raw potato starch decreases back fat thickness and dressing percentage but has no effect on the longissimus muscle quality of growing–finishing pigs

• Consuming RPS decreases back fat thickness of finishing pigs.
• RPS increases SCFA and affects gene expression in the colon of pigs.
• RPS affects fat metabolism in the livers of pigs.

This study was conducted to investigate the effects of long-term intake of raw potato starch (RPS) on carcass quality, luminal short chain fatty acid (SCFA) concentrations, the expression of host genes involved in fat metabolism in the liver, SCFA uptake, SCFA signaling and satiety regulation in the colonic mucosa of growing–finishing pigs. Thirty-six Duroc×Landrace×Large White growing barrows (70 days of age, 23.78±1.87 kg) were randomly allocated to corn starch (CS) and raw potato starch (RPS) groups, each group consisting of six replicates (pen) with three pigs per pen. Pigs in the CS group were offered a corn–soybean based diet, while pigs in the RPS group were put on a diet in which 230 g/kg (growing) or 280 g/kg (finishing) purified corn starch was replaced with purified RPS during a 100-day trial. Results showed that long-term intake of RPS significantly increased the feed intake of the pigs, but had no effect on body weight, average daily gain or feed:gain ratio. Consumption of RPS significantly increased the weight of the stomach and large intestine and their percentage of body weight, the mucosa thickness of the cecum and colon, and SCFA concentrations in the colon of pigs. Long-term intake of RPS decreased back fat thickness and dressing percentage but had no effect on the longissimus muscle quality of growing–finishing pigs. The expression of genes MCT1, FFAR2 and FFAR3 in the colonic mucosa was significantly up-regulated in pigs fed with the RPS diet as compared to pigs fed with the CS diet. Consuming RPS significantly down-regulated the expression of genes CPT1a and PPARα, and up-regulated the expression of the SREBP1c gene in the livers of pigs. The results suggest that RPS modulates gut SCFA concentrations and the expression of host genes, which can change the adipose tissue patterning in pigs.