Characterisation of undigested components throughout the gastrointestinal tract of broiler chickens fed either a wheat- or maize-based diet

This study was to characterise the undigested nutrients present along the gastrointestinal tract of birds offered common wheat-or maize-based diets, with the goal of optimising utilisation of enzymes to enhance digestive efficiency. Wheat-and maize-based diets were offered to 240 mixed-sex broilers (10 birds/pen; n = 12) from 1 to 35 d post-hatch. Digestibility of dry matter, starch, crude protein and non starch polysaccharides (NSP) were measured in the crop, gizzard, duodenum, jejunum, ileum, caeca and excreta at d 12 and 35 post-hatch. Analysis of nutrient levels in the excreta presented that more than 30% of nutrients provided in the feed was wasted, irrespective of wheat or maize diet type. On average, 92 g/kg crude protein, 92 g/kg insoluble NSP and 14 g/kg oligosaccharides were not utilised by birds at d 12 post-hatch. The quantity of water-insoluble NSP in the small intestine at d 12 was lower in birds offered the wheat-based diet compared to those fed the maize-based diet (P < 0.05), with the reverse being true for water-soluble NSP (P < 0.001). On average, 84 g/kg crude protein, 79 g/kg insoluble NSP and 9 g/kg oligosaccharides remained in the excreta at 35 d of age. At this time period, accumulation of feed in the gizzard was noted for birds offered both diets, but was more pronounced in those offered the maize-based diet (P < 0.001). Birds offered the maize-based diet demonstrated improved utilisation of oligosaccharides compared to those fed the wheat-based diet at both d 12 and 35 (P = 0.087 and P = 0.047, respectively). Protein utilisation in the jejunum and ileum was greater in birds offered the wheat-based diet compared to those fed the maize-based diet (P = 0.004 and P < 0.001, respectively). Thus, while both diets supported standard growth performance of birds, the degree and flow of nutrient disappearance along the gastrointestinal tract was influenced by cereal type and bird age. (c) 2021 Chinese Association of Animal Science and Veterinary Medicine. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The study aimed to characterize undigested nutrients in the gastrointestinal tract of birds fed wheat- or maize-based diets and found that over 30% of nutrients were wasted regardless of diet type. Protein, insoluble NSP, and oligosaccharides were the main undigested nutrients, with differences observed between wheat and maize diets. The utilization of oligosaccharides and protein varied between the diets, influencing nutrient disappearance along the gastrointestinal tract.