Arabinoxylan-oligosaccharides kick-start arabinoxylan digestion in the aging broiler

Abstract

While arabinoxylans (AX), an important dietary fiber fraction of wheat-based broiler diets, are known for exerting antinutritional effects in the gastrointestinal (GI) tract of broilers, the prebiotic potential of arabinoxylan-oligosaccharides (AXOS) is also well-documented. However, inconsistent performance responses as well as the effectiveness of low amounts of AXOS used in diets of previously conducted experiments put into question the classical prebiotic route being the sole mode of action of AXOS. The objective of this study was to investigate the effects of dietary AXOS addition on the rate of AX digestion in the gastrointestinal tract of broilers as a function of broiler age to gain more insight into the mode of action of these oligosaccharides. A feeding trial was performed on 480 one-day-old chicks (Ross 308) receiving a wheat-based diet supplemented with or without 0.50% AXOS, containing no endoxylanases. Digesta samples from ileum and caeca and fecal samples were analyzed for AX content, AX digestibility, intestinal viscosity, and microbial AX-degrading enzyme activities at 6 different ages (day 5, 10, 15, 21, 28, 35). Chicks fed from hatching with 0.50% AXOS demonstrated a higher ileal viscosity (P < 0.05). Also higher levels of AX solubilization and fermentation compared to control birds at 10 D were observed. This was noted by the higher total tract AX digestibility of water-extractable AX (WE-AX) and total AX (TOT-AX) at this age (P < 0.05). Although no significant difference in AX-degrading enzyme activities was observed among the dietary treatments, AXOS supplementation in young broilers was shown to stimulate or "kick-start" dietary AX digestion, thereby speeding up the development of a fiber-fermenting microbiome in the young broiler. This stimulation effect of AXOS could enable greater functional value to be extracted from dietary fiber in broiler feeds.

Keywords: arabinoxylan degradation; arabinoxylan-oligosaccharides; broiler age; dietary fiber.

Figure 1

Ileal viscosity (cP) for broilers fed a control (CTRL) and a 0.50% arabinoxylan-oligosaccharides supplemented (AXOS) wheat-based diet at 5 different broiler ages (day 10, 15, 21, 28, and 35). In I and II, the main effect of diet and broiler age is illustrated, respectively. Differing small letters a and b indicate a significant difference in ileal viscosity between dietary treatments (I) and broiler ages (II) (P < 0.05). Arrows indicate a different decline in ileal viscosity means for broilers fed a CTRL and an AXOS diet at one particular age (III).

Figure 2

Water-extractable arabinoxylan (WE-AX) and total arabinoxylan (TOT-AX) digestibility (%) at the level of the feces analyzed at 6 different broiler ages (day 5, 10, 15, 21, 28, and 35) for broilers fed a control (CTRL) and a 0.50% arabinoxylan-oligosaccharides supplemented (AXOS) wheat-based diet. Lowercase alphabets ^a,b and asterisk (*) denote significant differences between dietary treatment means at a particular age (interaction effect between diet × age, P ≤ 0.05 and P ≤ 0.10, respectively).