BACKGROUND: Antioxidant compounds and unsaturated fatty acids play an important role in improving the immune response and intestinal microflora in broiler chickens. Objectives: The aim of this study was to investigate the effects of different sources of antioxidant and soybean and rapeseed oils on humoral immune responses, intestinal microflora and some of the blood parameters of broiler chicken. Methods: A total of 480 male broiler chicks (Ross 308) were randomly allocated in a factorial arrangement (2×5) based on a completely randomized design with 10 treatments and 4 replicates during 42 days of age. Experimental factors consisted of different sources of antioxidant (rosemary, thymus and satureja essential oils at level of 300 ppm and vitamin E at concentration 200 mg/kg and without antioxidant) and vegetable oils (soybean and rapeseed oils at concentration of 4 percent of diet). Immune characteristics and intestinal microflora population were evaluated. Results: The use of different soybean and rapeseed oils had no significant effect on antibody titer (P>0.05) but the use of antioxidants improved immune responses against Newcastle disease (P<0.01). Also, the use of rosemary, thymus and satureja essential oils increased serum level of blood high density lipoprotein and reduced blood low density lipoprotein (P<0.001).  Furthermore, the concentrations of cholesterol and triglyceride increased in without  antioxidant treatment (P<0.001).Also, use of antioxidant treatments caused significant decrease of heterophil to lymphocyte ratio (P<0.05), then these result are consistent with the immune response against Newcastle disease. Furthermore, escherichia coli to lactic acid bacteria ratio increased in rosemary and thymus essential oils treatments compared with without antioxidant treatment (P<0.05). Conclusions:The use of dietary soybean and rapeseed oils did not have a significant effect on different traits of broiler chicken, but adding dietary antioxidants improved immune responses and intestinal microflora and in between different antioxidants, the use of essential oils compared with vitamin E  induced significant improvement of traits.

BACKGROUND: Chicken major histocompatibility complex region (MHC) is important in the productive traits, immune responses, resistance to infectious diseases and phylogenetic relationships. OBJECTIVES: This study was investigated for single nucleotide polymorphisms of MHC region related to the immune system in commercial broiler and layer chickens. METHODS: One hundred blood samples were taken from commercial broiler and layer chickens and genomic DNA was extracted by salting out method. The allelic polymorphisms were investigated in B-L, B-F and B-G loci using PCR-RFLP and MspI enzyme. RESULTS: For two commercial broiler and laying populations, in the 374 bp locus of B-L, only BB genotype was detected but in the 1048 bp locus of B-F, two genotypes of CG and GG were identified in broiler chickens. The C allele contained four bands of 515, 410, 75 and 47 bp, and the G allele with five bands of 410, 302, 213, 75 and 47 bp. In B-G (401 bp) locus, three genotypes of MM, MN and NN and two alleles of M with one band (401 bp) and N with two bands (350 and 51 bp) were identified. In total populations, the Shannon information index was calculated to be 0.45 and 0.73 in markers loci of B-F and B-G, and the fixation index values were -0.20 and 0.34, respectively. The highest observed heterozygosity index for B-F and B-G loci was 0.34 and 0.23, respectively. CONCLUSIONS: Considering the confirmation of the presence of polymorphism in two loci of the B-F (in commercial broiler population) and B-G (in commercial broiler and layer populations), these sites can be used as genetic marker in breeding programs to increase resistance to diseases.