effect of barley and enzyme on performance, carcass, enzyme activity and digestion parameters of broilers

introduction corn has been recently used for producing ethanol fuel in the major corn-producing countries such as the us and brazil. recent diversion of corn for biofuel production along with the increased world's demand for this feedstuff has resulted in unprecedented rise in feed cost for poultry worldwide. alternative grains such as wheat and barley can be successfully replaced for corn in poultry diets. these cereal grains can locally grow in many parts of the world as they have remarkably lower water requirement than corn. wheat and barley are generally used as major sources of energy in poultry diets. though the major components of these grains are starch and proteins, they have considerable content of non-starch polysaccharides (nsps), derived from the cell walls (olukosi et al. 2007; mirzaie et al. 2012). nsps are generally considered as anti-nutritional factors (jamroz et al. 2002). the content and structure of nsp polymers vary between different grains, which consequently affect their nutritive value (olukosi et al. 2007).wheat and barley are generally used as major sources of energy in poultry diets. the major components of these grains are starch and proteins, they have considerable content of non-starch polysaccharides (nsps), derived from the cell walls. nsps are generally considered as anti-nutritional factors. the content and structure of nsp polymers vary between different grains, which consequently affect their nutritive value. the major part of nsps in barley comprises polymers of (1→3) (1→4)-β- glucans which could impede growth factors and consequently carcass quality through lowering the rate and amount of available nutrients in the mucosal surface of the intestinal. materials and methods this experiment was conducted to evaluate the effect of corn and barley based diets supplemented with multi-enzyme on growth, carcass, pancreas enzyme activity and physiological characteristics of broilers. a total number of 375 one day old ross-308 broiler chickens were allocated randomly to 3 treatments with 5 replicates using a crd statistical design. treatments were included control, barley and barley+ enzyme. the experimental diets were formulated to have similar contents of crude protein, metabolizable energy, total non-starch polysaccharides (nsp). results and discussion according to the results, effect of barley with or without enzyme on growth performance at starter, grower and the entire period and also on carcass characteristics, pancreas enzyme activity and measures of ileal acidity and viscosity at the age of 42 were significant (p<0.01). birds fed barley diets gained significantly lower weight and carcass quality than those fed corn or supplemented with enzyme. the best growth performance and carcass characteristics belonged to control and the worst belonged to barley treatment, but enzyme supplementation of barley resulted in significant improvement of the traits (p<0.01). results indicated that birds on barley diet supplemented with multi-glycanase consumed significantly (p<0.01) higher feed than those fed corn. birds fed barley diets gained significantly lower weight and higher feed conversion ratio (fcr). also results indicated that birds on barley diet supplemented with multi-glycanase gained significant (p<0.01) higher dressing percentage as well as higher breast and leg percentage than those fed on barley. among all treatments the highest pancreas weight and the longest gut length belonged to barley treatment. the growth performance data are consistent with the viscosity of ileal digesta. the viscosity of intestinal digesta in chicks fed barley showed the highest value, which was significantly (p<0.01) greater than the control group fed on corn. the highest acidity and lowest viscosity of ileal content belonged to control and barley+ enzyme respectively, but reversely lowest acidity and highest viscosity related to barley treatment (p<0.01). in fact, nsp of barley increased digesta viscosity in the intestine. increased viscosity per se creates ideal environment for maximal proliferation of anaerobic and gram negative bacteria as resulted high nutrient consumption rate by the bacterial population and low absorption of digested nutrients in the gut by host. supplementation of barley diet with multi-glycanase significantly reduced the negative effects of nsp on proliferation of desirable bacteria (especially on probiotic-type bacteria) in the intestine through breakdown of nsp polymers. barley treatment had the highest activity of amylase and lipase in the pancreas, but enzyme supplementation significantly reduced the enzyme activity (p<0.01). this finding reflects the fact that water soluble nsp of barley impede pancreatic α-amylase and lipase activities in the intestinal lumen, which necessitate greater secretion of these enzymes from pancreas. research has shown that intestinal enzyme activity depends on dietary nutrient source and presence of anti-nutrients in the gut. conclusion in conclusion, nsp components of barley have adverse effects on digesta physicochemical properties of the gut and subsequent transmission of hydrolyzed products to the enterocyte cells and nutrient absorption. besides, nsp polymers of barley decrease the growth rate and carcass traits but increase the pancreatic α-amylase and lipase activities. such changes are remarkably restored by supplementing nsp-degrading enzymes to broiler diets.