Singh, Amit Kumar
Jha, Rajesh
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Feed and gut health management expenses of the flock account for over 70% in poultry production. To reduce the cost of production, nutritionists formulate broiler chickens feed with relatively cheaper alternative feedstuffs. Most of these alternative feedstuffs have high fiber content and low digestibility of nutrients. Thus, it is essential to test different exogenous enzymes to maximize nutrient utilization and enhance feed efficiency of fibrous feedstuffs for profitable broilers production. Better feed utilization also depends on improved gut health and microbial balance in the GIT of the birds. To reduce the load of pathogenic bacteria and maintain gut health for improved productivity, several antibiotic growth promoters (AGP) are used at a subtherapeutic level in poultry feed. However, due to the public health concern and risk of growing antibiotic resistance, the use of AGP has been restricted or regulated in several jurisdictions around the world. This further necessitates the finding of alternatives to AGPs and explore other effective nutritional strategies to modulate the gut health of broilers. Investigation and validation of several additives and functional foods for improving gut health and nutrient utilization are crucial to conveying the mechanistic understanding of these agents for nutritional programming in broilers. The principal objective of this dissertation research was to evaluate the effects of xylanase enzyme in feed and that of prebiotics application in ovo and post-hatch on broiler performance and gut health. To explore the effect of xylanase enzyme on broiler performance, two separate studies were conducted where xylanase was added to a corn-soybean meal (corn-SBM) based diet containing wheat bran in the first study and xylooligosaccharides (XOS) in the second study. Likewise, to examine the effect of prebiotics on gut health and production of broilers, two more studies were performed where oligosaccharides were applied in ovo in the third study, and resistant starch was fed during early post-hatch in the fourth study. The first study focused on the effect of xylanase supplementation on growth performance and cecal short chain fatty acid (SCFA) production in broilers fed corn-SBM diet containing different levels of fiber incorporated through wheat bran addition. The results from this study indicated that high fiber diets containing more wheat bran are more responsive to xylanase enzyme for improvement in feed efficiency while xylanase can equally improve SCFA production in both corn-based and wheat bran containing diet. The second study determined the effects of supplemental xylanase and XOS (as prebiotics) on growth performance, cecal SCFA production, and intestinal morphology of broilers fed corn-SBM diet. The results for this study demonstrate that xylanase can improve body weight gain without improving the feed efficiency of corn-SBM diets while both xylanase and XOS can lead to increased cecal fermentation in broilers. Thus, xylanase enzyme could be used in different basal formulations to improve growth performance of broilers, and it can potentially be used along with XOS prebiotics for better cecal fermentation capacity of broilers that might be more useful in a challenged environment. The third study was conducted to investigate the beneficial role of four different oligosaccharides (differing in chain length) as prebiotics when fed in ovo to the embryo of broilers through their amniotic fluid. The gene expression and histomorphometric study demonstrated the potency of xylotriose in stimulating T-cell based adaptive immunity and cecal SCFA compared with controls. The fourth study concentrated on evaluating the effect of resistant starch type 2 and type 4 feeding as prebiotics during early post-hatch in broilers. The results of this study revealed that resistant starch type 4 can be a candidate for immunomodulation in early post-hatch feeding but may not provide persistent benefit if used for a short duration. The in ovo oligosaccharides and early post-hatch resistant starch feeding can support the build-up of immunity in premature birds, but further studies are warranted to ascertain their effects to be used in combination with regular vaccine programs. Collectively, this dissertation elaborates on the application of xylanase enzyme, oligosaccharides, and resistant starch as alternative resources to improve gut health in broilers, but in the present form, they do not exhibit a greater potency to completely replace the AGPs in feed. However, further research is required to unravel the mechanistic role of existing additives to be used as an alternative to AGP and additional improvement in their potency and efficacy is required to promote their use to obtain the specific health benefits.
Nutrition, Animal sciences, broilers, in ovo feeding, mannanoligosaccharides, resistant starch, xylanase, xylooligosaccharides
195 pages
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