The Effect of Particle Size of Different Sources of Insoluble Fiber on Energy and Protein Efficiency Ratios and Welfare Indices of Broiler Chickens Fed a Barley-Based Diet

Introduction:

 Barley is one of the cereal grains that used to supply energy in broiler diets, but high content of non-starch polysaccharides (NSP) such as β-glucans, has limited the application of it in poultry diets. It has been shown that NSP can increase intestinal viscosity, reduce litter quality, compromising the access of digestive enzymes to dietary components by protecting lipids, starch, and protein, and cause poor productive performance. Recent studies have shown the inclusion of moderate amounts of insoluble fiber or coarse particles in the diet increases the retention time of the digesta in the upper part of the gastrointestinal tract (GIT) (i.e., from crop to gizzard), improves the development and function of the gizzard, and increase the secretion of HCl in the proventriculus in broilers. The objective of this study was to determine the influence of supplementing insoluble fiber sources in different particle sizes on energy and protein efficiency ratios, intestinal morphology and welfare indicesin broiler chickens fed barley based-diets.

Materials and Methods:

 Ross 308 (n=308) were used in a completely randomized design with 7 treatments, 4 replicates and 11 chickens per replicate for 42 days. The dietary treatments included: a barley based- diet (control, CTL) or Sunflower hulls (SFH), Sugarcane bagasse (SB), and Wheat bran (WB) ground through a 1.0 (fine) or 3.0 mm (coarse) screen that were added to the control diet at 3.0%. The CTL diet included 3.0% fine silica sand as filler that was replaced by the same amount of insoluble fiber sources in the corresponding diets. The dry sieving method was used to determine the particle size distribution of diets. Body weight gain (BWG) and feed intake (FI) of each pen were recorded. Feed conversion ratio (FCR) adjusted for mortality and it was calculated by dividing FI with BWG for each period of the experiment (1-21 d and 22-42 d) in total period (1-42 d). The welfare indices were examined at 42 days of age. Litter moisture was measured on days 35 and 42 of the rearing period. For the purpose of small intestinal morphological studies, the digestive tract of slaughtered birds (two birds of each replicate) was removed at 42 days of age and from two small intestine sections including duodenum and Jejunum, two centimeter-long Isolated.

Results and Discussion:

 The results showed that different sources of insoluble fiber showed significant effect (p < 0.05) on energy and protein efficiency ratios during growth period (22-42 days of age) and whole experimental period (1-42 days of age). During the entire experimental period (1-42 d), dietary inclusion of SFH (coarse and fine) and WB (fine particle size) improved BWG as compared to the CTL diet (P < 0.05). Dietary inclusion of WB and SFH in both particle sizes (coarse and fine) and SB (coarse particle size) improved FCR as compared to the CTL diet from 1-42 d (P < 0.05). The villus height and villus height to crypt depth ratio in duodenum of treatments fed insoluble fiber with the exception of sugarcane bagasse with particle size of 1 mm showed significant increase (p < 0.05) in comparison to control diet. The number of goblet cells in jejunum of treatments fed insoluble fiber significantly decreased (p < 0.05) when compared to control group. The relative frequency of score two welfare indices was higher in control treatment. Reports have indicated that soluble and insoluble non-starch polysaccharides (NSp < /strong>) affect digestive organs and intestinal morphology of broilers. Coarse fiber and large particles may increase villi length in gastrointestinal tract. Therefore, increased villi length resulted in increased surface area for more absorption of nutrients. Currently, the control of litter moisture is a priority in the broiler industry to reduce productivity losses and minimize bird welfare issues due to footpad dermatitis (FPD), hock burn (HB), and ammonia production. Wet litter was found to increase FDP, HB, and breast irritations and reduce broiler performance. The inclusion of 3% fiber in the diet resulted in lower litter moisture content.

Conclusion:

 Overall, the results showed that dietary inclusion of three percent of different insoluble fiber sources improved energy and protein efficiency ratios, intestinal morphology, litter moisture and welfare parameters of broilers fed barley-based diet.