The Effect of source and particle size of fiber on performance and gastrointestinal ‎tract characteristics in broiler chickens up to 21 days of age

The study was conducted to evaluate the effects of fiber source and particle size on growth performance and gastrointestinal tract characteristics in broiler chickens from d 1 to 21. A total of 420 male broiler chickens were randomly distributed in 7 treatments and 6 replicates per treatment, which were arranged factorially. Experimental treatments including three insoluble fiber sources, 3% (sunflower hulls, SFH; rice hulls, RH; and camelina hulls, CH), and two sizes of fiber particles (fine (1 mm) and coarse (3 mm)), and a control group (without fiber addition). Main effects of fiber sources and particle size on feed intake, body weight gain and feed conversion ratio were not significant (P˃0.05), whereas, the inclusion of fine SFH improved body weight gain compared to the control group (P<0.05). The main effects of source and size of fibers did not affect gizzard weight, although the inclusion of coarse SFH tended to increase gizzard weight compared to control (P=0.08). The SFH and RH-containing diets improved the relative jejunum weight than the CH-containing diet (P<0.05). Experimental treatments did not influence the pH of proventriculus and gizzard, as well as the relative weights of duodenum and ileum. The main effect of fiber particle size was significant in term of cecum weight, so that coarse grinding increased cecum weight compared to fine grinding (P<0.05). Based on the results of this research, dietary inclusion 3% of sunflower hulls, rice hulls, and camelina hulls in the diet of broilers had no negative impacts on the growth performance of broiler chickens, while diluting the diet with sunflower hulls could improve body weight and gizzard weight.