effect of guar meal and beta-mannanase on growth performance and carcass quality of broiler chickens

this experiment was carried out to evaluate the effect of different levels guar meal and β-mannanase on broilers male chicken. in this experiment , four hundred ross day old broiler chicks were randomly assigned to a 4×2 factorial design to feed broiler chickens diets containing guar meal at 4 level of guar meal (0, 3, 6 and 9%) with five replications of each treatment with or without β-mannanase. ten chicks were assigned to each pen. the diets were based on maize-soybean meal were used: starter, 8-19 days; grower, 19-35 days; and finisher, 35-42 days. all starter, grower and finisher diets were formulated to have 21.5, 20.5 and 19% cp and 3050, 3100 and 3150 kcal/kg metabolizable energy, respectively. average daily gain and daily feed intake were recorded over 19 and 42 days. results indicated that addition of the guar meal to rations did not reduce body weight, feed consumption and feed conversion ratio. enzyme supplementation did not significantly effect on body weight, feed consumption and feed conversion ratio. relative weights of abdominal fat, thigh, gallbladder, liver and pancreas were not significantly affected by consumption of the guar meal at any level when compared with the control. inclusion of the guar meal in the diet significantly decreased breast weight. the addition of β-mannanase to the diets significantly reduced ileal viscosity compared with the control group in 19 day. the results of this study show that replacement of guar meal up to 9% significantly with and without β-mannanase in broilers diet have no adverse effects on body weight, feed intake and feed conversion ratio, but leads to a reduction in breast weight. guar meal can be used up to 3% of broiler diet with no adverse effect, but its high level (9%) reduced breast meat percentage.