Impact of single or co-dietary inclusion of native or methylated soy protein isolate on growth performance, intestinal histology and immune status of broiler chickens

Abstract

This study was designed to study the effect of single or co-dietary inclusion of native soy protein isolate (NSPI) and/ or methylated soy protein isolate (MSPI) on growth performance, small intestine histology and immune status of broiler chickens. For this purpose, 250 one-day old broiler chicks (Ross 308 broiler) were randomly assigned into five experimental groups with five replicates per group (50chicks/group). The experimental treatments include; T1: control group (basal diet without additives); T2: basal diet + 2%NSPI + 0% MSPI (2NSPI:0MSPI); T3: basal diet + 0%NSPI + 2% MSPI (0NSPI:2MSPI); T4: basal diet + 1%NSPI + 1% MSPI (1NSPI:1MSPI); T5: basal diet + 2%NSPI + 2% MSPI (2NSPI:2MSPI). The experimental period was 35 day and water and feed were provided ad-libitum. Results revealed that chickens fed diets supplemented with 2NSPI:0MSPI and 1NSPI:1MSPI had significant (P < 0.05) heavier final BW, BWG and best FCR compared to other dietary treatments. Liver, bursa and thymus percentages significantly (P < 0.05) increased in broilers fed on diets supplemented with 0NSPI:2MSPI and 2NSPI:2MSPI as compared to control group. Gamma globulins and growth hormone were significantly increased by single or double dietary supplementation with NSPI and MSPI. Inclusion of 2NSPI and 1NSPI:1MSPI resulted in broad and thickened villous tips in most intestinal villi and an increase in the absorptive surface. Taken together, single supplementation with 2% NSPI or co-dietary supplementation with 1NSPI:1MSPI had positive effect on growth performance and gut health. Both single and co-dietary supplementation with NSPI and MSPI had potential effects on the immune status of broiler chickens.