Abstract

This study was conducted to evaluate the effects of replacing soybean meal (SBM) protein with canola meal (CM) protein on productive performance, nutrient digestibility, immune response, lymphoid organs, blood parameters, carcass fatty acids and cecum microbiota of broilers. A total of 160 one d-old Arbor Acres broiler chicks were randomly allocated to 4 dietary treatments of 5 replicates, where, CM protein replaced SBM protein at 0, 30, 60, and 90% for a 39 days feeding trial. The results showed no significant differences in productive performance parameters among control, 30% and 60% treatment groups, while, at 90% replacement level, all values decreased (P < 0.0001) all over the experimental period. The 90% replacement group showed depression of crude protein (P < 0.001) and crude fiber (P < 0.001) digestibility and spleen relative weight (P = 0.0386) with increase of thymus (P = 0.0555), bursa (P = 0.0334) and thyroid relative weight (P = 0.0276) as well as thyroid hormones (P = 0.0034, 0339) for T₃, T₄, respectively, while, there were no significant differences among control, 30% and 60% treatment groups for those criteria. However, CM levels had no effect on serum haemagglutination inhibition (HI) titer against Newcastle disease. CM significantly decreased serum cholesterol content (P = 0.0002) while increased HDL (P = 0.0532), compared to the control. CM levels showed an increase in carcass meat content of unsaturated fatty acids content (P < 0.0001) as the replacement level gradually increased. Erucic acid did not detected in carcass. All CM levels decreased cecum content of E. coli (P = 0.0051) while increased that of Lactobacillus (P = 4094). Conclusively, CM can be used safely in broiler diet to replace up to 60% of SBM protein without negative effects on growth and immune response of broilers.

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