| This research was conducted to investigate the effects of Canola meal and flavin-containing monooxygenases3(FMO3) genotype on performance, deposition of TMA in egg yolk, and cecal microbiota in hens for assessing the best additive amout of canola meal, providing the scientic basis of resonable use of Canoala meal and researching fishy egg. The present research included 3 trials which were described as follows.Experiment 1:Genotyping of fishy-egg tainting hens in a brown egg layer were studiedA total of 1 508 hens were genotyped for a A/T polymorphism at position nt 1034 of the chicken FMO3 c DNA sequence(T329S for amino acid sequence). A PCR-RFLP method was developed to analysis the distribution of the mutation in hens. Genotype of AA(wild type), AT(heterozygous type) and TT(mutant type) were found with percentage of 1.59%, 84.68% and13.73%, respectively. The allelic frequencies of T was higher than that of A, and the allelic frequencies were not in Hardy-Weinberg equilibrium(P<0.0001) in the laying hens strain.Experiment 2:Effect of Canola meal suplementation on Proformance, Egg Quality, Yolk TMA of Different FMO3 genotye in Laing HensThis experiment was conducted to investigate the effects of dietary Canola meal level on performance, egg quality, and trimethylamine(TMA) content in egg yolk of flavin-containing monooxygenases 3(FMO3) genotype laying hens. A total of 336 laying hens, consisting of 48 hens of AA genotype, 144 hens of AT genotype and 144 hens of TT genotype, were used in this study. Hens with AT and TT genotypes were randomly assigned to 4 groups with 6 replicates per group and 6 birds per replicate, and those with AA genotypes were randomly assigned to 4 groups with 6 replicates per group and 2 birds per replicate. The laying hens in four groups were fed a basal diet supplemented with 0(control), 7%, 14% and 21% Canola meal, respectively. The experimental period lasted for 6 weeks. The results showed as follows: 1) dietary Canola meal level, FMO3 genotype and the interaction of dietary Canola meal level and FMO3 genotype significantly affected average daily intake(P<0.05), but had no significant effects on average egg weight and the ratio of feed to egg(P>0.05). The average daily feed intake in 14% and 21% Canola meal level group was significantly lower than that in control group(P<0.05). The average daily feed intake and egg production in AA genotype group were significantly lower than those in the other groups(P<0.05). 2) Dietary Canola meal level, FMO3 genotype and the interaction of dietary Canola meal level and FMO3 genotype had no significant effects on egg-shape index, eggshell strength, albumen height and Haugh unit(P>0.05). But dietary Canola meal level had significant effect on the value of egg yolk color, and 21% Canola meal level group was significantly lower than control group and 7% Canola meal level group(P<0.05). 3) Dietary Canola meal level, FMO3 genotype and the interaction of dietary Canola meal level and FMO3 genotype had significant effect on TMA content in egg yolk(P<0.05). The TMA content of egg yolk was improved with increasing dietary Canola meal level, and TMA content in Canola meal groups was significantly higher than that in the control groups(P<0.05). The TMA content in TT genotype group was significantly higher than that in AA and AT genotype groups(P<0.05). According to the regression equation of the TMA content(Y) and dietary Canola meal level(X): Y=25.457X+2.852(R2=0.976 5, TT genotype), Y=7.685 7X+1.943(R2=0.952 5, AA genotype), dietary Canola meal level should be lower than 4.62%(TT genotype hens) or 20.76%(AA genotype hens) to make the TMA content of yolk lower than the estimated human olfactory threshold. The results suggest when laying hens with TT genotype feed Canola meal do not lay fishy-taint eggs, hens with AA and AT genotype will not lay the eggs, too; thus, dietary Canola meal level lower than 4.62% can not product fishy egg, and has no negative effect on performance and egg quality.Experiment 3:Effect of dietary Canola meal supplementation under different flavin-containing monooxygenase 3 genotype on caecal microbiota in laying hensTo evaluate the effect of flavin-containing monooxygenase 3(FMO3) genotype and dietary Canola meal supplementation on cecal bacteria in laying hens, a 3 × 2 two-factorial arrangement was employed with FMO3 genotype(AA, AT, and TT) and dietary Canoala meal supplemental levels(0 and 14% of diet) as main effects. At 50 wk of age, 72 hens of AT genotype and 72 hens of TT genotype were randomly allotted to one of the 2 dietary treatments, and each dietary treatment consisted of 3 replicates with 6 birds each. A total of 12 hens with AA genotype were allotted to one of the 2 dietary treatments that consisted of 3 replicates with 2 hens. Hens were fed the diet with 0% Canoala meal supplementation for one wk of adaptation followed by a 6-wk trial period. Trimethylamine(TMA) concentration in egg yolk(TT hens) and caecal chyme was significantly increased by dietary supplemental Canoala meal. A total of 1 617 operational taxonomic units(OTUs) were identified from all cecal samples. Both bacterial abundance and diversity were significantly increased by Canoala meal diets(P<0.05). Weighted Uni Frac, and Nonmetric Multidimensional Scaling(NMDS) indicated distinct clustering based on the diet types regardless of FMO3 genotype. A total of 24 phyla and 229 genera were identified from all cecal samples; Bacteroides, Firmicutes, and Proteobacteria were the most dominant phyla in all samples. Compared with control diets, the proportion of Firmicutes, Proteobacteria, Firmicutes : Bacteroides, and some low-abundance phyla was significantly higher in dietary Canoala meal, whereas the abundance of Bacteroides was considerably lower in Canoala meal diets. The abundance of 42 genus varied with diets. Seven phyla and 36 genus showed significantly positive correlation with TMA concentration of caecal chyme. This study demonstrated that dietary Canoala meal, regardless of FMO3 genotype, significantly increased bacterial diversity and changed the structure of the cecal microbiome. |
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