Effect of Dietary Supplementation with Coarse or Extruded Oat Hulls on Growth Performance, Blood Biochemical Parameters, Ceca Microbiota and Short Chain Fatty Acids in Broiler Chickens

SIMPLE SUMMARY: Oat hull (OH) is an excellent source of insoluble fiber, which may improve chickens’ gastrointestinal health by promoting the growth of beneficial bacteria. Extrusion may modify OH fiber fractions resulting in a differential effect on gut microbiota. Thus, the purpose of this study was to determine the effect of dietary supplementation with coarse or extruded OH on growth performance, blood biochemistry and cecal short-chain fatty acids (SCFA) and microbiota of broiler chickens. Broiler chickens were assigned four diets: a corn-wheat-soybean-based diet, an antibiotics diet, 3% coarse OH (COH), and 3% extruded OH (EOH) supplemented diets. Birds fed COH and EOH had reduced BWG, but there was no diet effect on FCR. There was a significant increase in relative gizzard weight among birds that were fed COH. Dietary treatments had no effect on blood biochemical parameters and SCFA concentration. Cecal microbial composition of chickens was mostly comprised of Firmicutes and Tenericutes. Seven bacteria species that were differentially abundant among treatments were identified ABSTRACT: The purpose of this study was to determine the effect of dietary supplementation with coarse or extruded oat hulls on growth performance, blood biochemistry, cecal microbiota, and short chain fatty acids (SCFA) in broiler chickens. Chickens were randomly allotted to four dietary treatments consisting of a corn-wheat-soybean meal-based diet (Basal), Basal + Bacitracin methylenedisalicylate (BMD), Basal +3% coarse OH (COH), and basal +3% extruded OH (EOH). Feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were recorded weekly. On day 36, eight chickens/treatment were euthanized, blood samples were collected, and organ weights were determined. Cecal digesta samples were collected for the determination of SCFA concentration and microbial DNA sequence. Data were subjected to ANOVA using the mixed procedure of SAS. Alpha diversity was estimated with the Shannon index, and the significance of diversity differences was tested with ANOVA. Birds fed COH and EOH had reduced (p < 0.05) BWG, but there was no effect of treatment on FCR. There was a significant increase (p = 0.0050) in relative gizzard empty weight among birds that were fed COH, compared to the other treatments. Dietary treatments had no effect on blood biochemical parameters and SCFA concentration. Cecal microbial composition of chickens was mostly comprised of Firmicutes and Tenericutes. Seven OTUs that were differentially abundant among treatments were identified. In conclusion, supplementation of broiler chickens’ diets with 3% COH or EOH did not affect the FCR, blood biochemical parameters and SCFA concentration, but modified few cecal microbiota at the species level. Dietary supplementation with COH but not EOH significantly increased the relative gizzard weight.