Nutritional evaluation of soybean hulls with or without β-mannanase supplement on performance, intestinal morphometric and carcass yield of broilers chickens

Abstract

The objective was to evaluate the performance, intestinal morphology and carcass yield of broilers fed corn-soybean meal (SBM) diet or corn-SBM-soybean hull (SH) with or without β-mannanase supplementation. Thousand four hundred and forty Cobb Slow-male-chicks were housed design following a factorial scheme 2 x 2 (corn-SBM diet and corn-SBM-SH diet vs with and without β-mannanase), composing 4 treatments and 9 replicates each treatment, with 40 birds each replicate. At 21 days, corn-SBM diet supplemented with β-mannanase resulted in better (p<0.05) feed conversion. At 42 days, the weight gain (p<0.05) and feed intake (p<0.05) of the birds fed diets containing SH was 2.6% and 2.9% higher than that of birds fed corn-SBM diets, respectively, independent of β-mannanase supplementation. Birds supplemented with β-mannanase had a lower length of villi (p<0.05) and absorption area (p<0.05) of jejunum mucosa, and higher (p<0.05) relative liver weight. Diets with SH and without addition of β-mannanase resulted in higher relative liver weight (p<0.05) and lower percentage of fat in the carcass. It was not found statistical differences (p>0.05) in the quality of the poultry litter with the inclusion of the enzyme in the diet. The use of β-mannanase in diets with higher concentration of fiber improves the feed conversion of broilers from 1 to 21 days and can be an important nutritional and economic strategy in situations of unavailability of raw material of better quality. Corn-SBM-SH diet resulted in greater weight gain at 42 days than corn-SBM diet.