Alteration of growth performance, glycolipid metabolism, and bone characteristics of broiler chickens in response to different inclusion levels of dietary wheat.

Objective: The aim of this study was to evaluate the effects of different levels of wheat inclusion on growth performance, glycolipid metabolism, and tibial properties of broiler chickens.

Methods: A total of 480 1-d-old male broiler chickens were initially fed identical starter diets until d 10. Subsequently, they were divided into 3 treatments consisting of 8 replicates with 20 birds per replicate, i.e., i) low-level wheat addition group, with wheat ratios of 15% and 25% during the grower and finisher periods, respectively; ii) medium-level wheat inclusion group, incorporating 30% and 40% wheat in the grower and finisher diets, respectively; and iii) high-level wheat addition group, containing 55.8% and 62.4% wheat in the grower and finisher diets, until d 39.

Results: When compared to the low- and medium-level wheat diet, the high-level wheat inclusion in the diet increased feed intake and reduced the feed conversion ratio (both p<0.01), which was accompanied by a longer jejunum (p = 0.031). Meanwhile, the high-level addition of wheat displayed a decreased abundance of Ruminococcin, Bacteroidetes, and Lactobacillus than the low-wheat group. With the increase of the proportion of wheat treatment, the contents of cholesterol, triglyceride, and high-density lipoprotein cholesterol were elevated in serum, whereas the concentration of serum C-terminal cross-linked telopeptide of type I collagen, a bone resorption marker, was decreased. In addition, the diet with medium and high levels of wheat improved the yield load of tibia, along with comparable bone dimension and weight.

Conclusion: The medium- and high-level wheat additions increased serum glycolipid deposition and enhanced tibial mechanical properties, whereas the high-level wheat diet compromised the growth performance of broiler chickens, which might be associated with the alteration of gut microbiota.