Types and dietary levels of resistant starches modulated growth performance and intestinal environment in broiler chickens

In a 21-d study, 480 Cobb 500 (off-sex) male chicks were used to evaluate the effects of feeding different types and levels of resistant starches (RS) on growth, digesta pH, digestive tract morphometry and jejunal histomorphology in broiler chickens. The birds were allocated to 10 treatments in a 3 × 3+1 factorial arrangement. The factors were 3 RS types (RST): banana starch (BS), raw potato starch (RPS), and high-amylose corn starch (HCS); each at 3 levels (RSL) 25, 50 or 100 g/kg plus a corn-SBM control. Birds and feed were weighed on d 0, 8 and 21. On d 21, samples of tissues and digesta were used for morphometry, histomorphology, and digesta pH determination. There were no significant main effects or RST × RSL for d 0 to 21 weight gain but there was a tendency for RST × RSL (P= 0.087) for feed intake. Feed intake was higher (P < 0.01) for birds receiving RPS compared with the control whereas FCR tended to be higher (P = 0.056) for birds receiving BS compared with the other RST or control. There were no RST × RSL or RST main effect for digesta pH in the small intestine or ceca but jejunal pH tended to be lower (P = 0.069) at 100 g/kg RSL. RST × RSL was significant (P < 0.05) for relative ileal length with general increase in ileal length with increasing level of all RST except HCS. There was trend for RST × RSL (P = 0.096) for relative ceca weight due to increase of ceca weight with increasing BS and RPS levels but not with HCS. Relative duodenum weight at RSL 50 and 100 g/kg tended to be greater (P = 0.085) than 25 g/kg level or the control. Jejunal villi were longer (P < 0.05) for all RST compared with control but longest villi were in birds receiving HCS diet; and villi height tended to increase (P = 0.058) with increasing RSL. Birds receiving RPS and HCS had deeper (P < 0.01) crypt than birds on control and BS. The current study showed that the effects of RS on growth performance (mainly FCR differences modulated by feed intake effects), gut morphology and villi and crypt characteristics depend on both the type and level of RS in the corn-soybean meal diet.

Key Words: resistant starches, growth, pH, histomorphology, chickens.

Presented at the 10th Symposium on Gut Health in Production of Food Animals 2022, St. Louis, USA.