Effect of oat hulls as a free choice feeding on broiler performance,short chain fatty acids and microflora under a mild necrotic enteritis challenge

Structure of fibre has been reported to enhance performance,intestinal function and modify the composition and quantity of the microbial population in the chicken gastrointestinal tract.It is hypothesised that insoluble fibre in oat hulls may improve gut health and reduce intestinal Clostridium perfringens number.This research assessed the effect of free choice oat hulls(OH) on performance and gut microbiota in broilers during a mild(subclinical) necrotic enteritis(NE) challenge.A total of 240 dayold male Ross 308 broiler chickens were assigned to 24 cages in a 2×2 factorial arrangement of treatments.Factors were challenge - or +; and OH - or +.On d 16,challenged broilers had lower weight gain and feed intake(P < 0.05) compared with unchallenged broilers.Ond 16,broilers given OH had lower feed intake(P < 0.05) and tended to have lower(P=0.062) feed conversion ratio(FCR) compared with those without access to OH.Broiler performance,however,was not affected by OH nor by challenge on d 24 and 35.The broilers given OH had heavier gizzards(P < 0.05) compared with those without OH at d 35 but not at d 13 or 16.Increased numbers of C.perfringens(P < 0.001) and reduced numbers(P < 0.05)of Lactobacillus and Salmonellae were observed in the caecal contents of challenged broilers on d 16.Challenged broilers had a lower concentration of caecal acetic acid(P < 0.01) compared with unchallenged broilers at d 16.The broilers given OH had lower concentrations of caecal acetic acid(P < 0.05),propionic acid(P < 0.05),and valeric acid(P < 0.01) compared with those without access to OH.An OH by challenge interaction on succinic acid concentration was observed on d 16(P < 0.05).Oat hulls elevated the caecal succinic acid concentration only in the unchallenged broilers.This study indicated a positive role of OH through improved gizzard function and increased succinic acid in the gut but its role in controlling NE was not conclusive.