Choline diet improves serum lipid parameters and alters egg composition in breeder ducks

Background

Choline is an important nutrient, playing key roles in numerous metabolic pathways relevant to animal health.

Objectives

The objective of this study was to evaluate the effect of dietary choline on the lipid parameters, cardiovascular health (CVH), and levels of egg trimethylamine (TMA) and cholesterol in breeder ducks during the late laying period.

Methods

A total of 60 Jingjiang ducks were randomly separated into six replicates of 10 ducks each. After peak production until 65 weeks of age, the birds were fed a control basal diet. The same ducks served as the control group until 65 weeks of age, when the same ducks served as the choline‐supplemented group, after 15 days of dietary choline supplementation at 2955 mg/kg choline above and over the basal diet initially provided. The 15 days of choline supplementation included an initial 5‐day acclimatisation period.

Results

Dietary choline supplementation increased serum TMA (p < 0.01), high‐density lipoprotein cholesterol, very low‐density lipoprotein, and triglyceride levels in older breeder ducks. However, it did not change the levels of trimethylamine N‐oxide but decreased the atherosclerosis index compared with those of the control group (p < 0.01). Moreover, it increased (p < 0.01) the egg yolk TMA levels but did not change the concentrations of cholesterol in egg yolk.

Conclusions

Dietary choline supplementation had a beneficial effect on lipid parameters and CVH in older breeder ducks, although it increased the serum and egg yolk TMA levels.

Associations of the T329S Polymorphism in Flavin-Containing Monooxygenase 3 With Atherosclerosis and Fatty Liver Syndrome in 90-Week-Old Hens

This study aimed to evaluate the effects of the spontaneous genetic mutation T329S in flavin-containing monooxygenase 3 (FMO3) on atherosclerosis (AS), fatty liver syndrome (FLS), and adiposity in 90-week-old layers. At 90 weeks of age, 27 FMO3 genotyped Rhode Island White chickens (consisting of nine AA hens, nine AT hens, and nine TT hens) with normal laying performance were selected. The AS lesions, incidence of FLS, fat deposition, metabolic characteristics, and production performance of these egg-layers with different FMO3 genotypes were assessed. The T329S mutation in TT hens reduced the AS lesions (P < 0.01) and altered the plasma metabolic indices more than it did in the AA and AT hens. Furthermore, it reduced the incidence of FLS, hepatic triglyceride deposition (P < 0.05), liver indices (P < 0.05), and fat deposition (P < 0.05) in the subcutis and abdomen of TT hens compared to those of AA and AT hens. Moreover, as an effect of T329S, TT hens laid a higher than average number of eggs and maintained a higher egg-laying rate from 68 to 90 weeks than AA and AT hens. Our study confirmed that the T329S mutation in FMO3 could reduce the development of AS lesions, the incidence of FLS, and fat deposition, which are associated with changes in plasma and hepatic metabolic indices and improvements in the laying performance of older layers. Our results may provide a new strategy for using the T329S mutation to improve the health status and production performance of layers during the late laying period.

T329S Mutation in the FMO3 Gene Alleviates Lipid Metabolic Diseases in Chickens in the Late Laying Period

Simple Summary

The lipid deposition and health status of egg-laying hens is crucial to the development of the poultry industry. This study aimed to evaluate the effects of genetic variations in the flavin-containing monooxygenase 3 (FMO3) on the lipid metabolic diseases of laying hens during the late laying period. The results showed that the T329S mutation in FMO3 moderated the lipid parameters and decreased the atherosclerotic lesions and hepatic steatosis in laying hens with homozygous T329S mutation. In conclusion, the T329S mutation in FMO3 is closely associated with the improvement of lipid metabolic diseases in laying hens during the late laying period. The results of this study may contribute to overcoming the challenge of lipid metabolic diseases in laying hens during the late laying period.

Abstract

The T329S mutation in flavin-containing monooxygenase 3 (FMO3) impairs the trimethylamine (TMA) metabolism in laying hens. The TMA metabolic pathway is closely linked to lipid metabolic diseases, such as atherosclerosis and fatty liver disease. We aimed to evaluate the effects of the T329S mutation in FMO3 on lipid metabolism in chickens during the late laying period. We selected 18 FMO3 genotyped individuals (consisting of six AA, six AT, and six TT hens) with similar body weight and production performance. The lipid metabolism and deposition characteristics of the laying hens with different genotypes were compared. The T329S mutation moderated the serum-lipid parameters in TT hens compared to those in AA and AT hens from 49 to 62 weeks. Furthermore, it reduced the serum trimethylamine N-oxide concentrations and increased the serum total bile acid (p < 0.05) and related lipid transporter levels in TT hens. Moreover, it significantly (p < 0.01) decreased atherosclerotic lesions and hepatic steatosis in TT hens compared to those in the AA and AT hens. Our findings may help improve the health status in laying hens during the late laying period.

Effects of dietary rapeseed meal supplementation on cecal microbiota in laying hens with different flavin-containing monooxygenase 3 genotypes

To evaluate the effect of dietary rapeseed meal (RM) supplementation on cecal trimethylamine and bacteria in laying hens with different flavin-containing monooxygenase 3 (FMO3) genotypes, a 3 × 2 2-factorial arrangement was employed using FMO3 genotypes (AA, AT, and TT) and dietary RM (0 and 14% of diet) as the main effects. At 50 wk of age, 36 hens of AT genotype and 36 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 0% RM in a corn-soybean (SM) diet for one wk before the 6-week feeding trial period. Dietary RM supplementation increased trimethylamine (TMA) concentrations in both egg yolks (P < 0.0001) and cecal chyme (P < 0.0001). Dietary RM supplementation increased bacterial abundance and diversity (P < 0.0001). Weighted UniFrac, Nonmetric Multidimensional Scaling, and analysis of similarity (R-ANOSIM = 0.1516; P-value = 0.014) indicated distinct clustering was dependent on diets rather than FMO3 genotypes. Twenty-four phyla (most dominant, Bacteroides, Firmicutes, and Proteobacteria) and 229 genera were identified in the cecal samples. Compared with the SM diets, RM diets increased the proportion of Firmicutes (P = 0.004), Proteobacteria (P = 0.006), and Firmicutes:Bacteroides (P = 0.001), and some low-abundance phyla (P < 0.01), whereas the abundance of Bacteroides was lower (P = 0.0002). The abundance of 42 genera varied with dietary types. Six phyla and 35 genera were positively correlated with TMA concentration in the cecal chyme. In conclusion, the major TMA-producing bacteria in cecal were from Firmicutes and Proteobacteria phyla. The major TMA-producing bacterial genera could be from the genera that positively correlated with TMA concentration.

Fishy Odor and TMA Content Levels in Duck Egg Yolks

The differences between the trimethylamine (TMA) content levels in duck and chicken egg yolks under normal dietary conditions were compared. Moreover, the association between the polymorphisms of the duck FMO3 gene and TMA content levels in duck egg yolks was analyzed. Then, to detect the mutations associated with the fish-flavor trait, duck populations were selected for a high-choline diet experiment, which was followed by full-length sequencing of the FMO3 exons. The results showed that the TMA content levels in duck eggs (3.60 μg/g) were significantly higher than those in chicken eggs (2.35 μg/g) under normal dietary conditions (P < 0.01). With regard to the high-choline diet, the average TMA content levels in duck egg yolks (9.21 μg/g; P < 0.01) increased significantly. Furthermore, 5 SNPs reported in Ensembl database were detected in duck FMO3 exons. However, no mutation loci were found to be significantly associated with the TMA content levels in duck egg yolks. Besides, duck liver FMO3 mRNA expression levels were not associated with the TMA content levels. The results indicated that excessive TMA deposition in duck eggs is one of main factors causing the fishy odor in duck eggs, and the addition of choline in the ducks' diets was responsible for inducing an increase in the TMA content levels in duck eggs.

PRACTICAL APPLICATION

Our study can help to diminish the fishy taste in duck eggs by reducing the amount of supplemented choline. Furthermore, this study laid a solid foundation for revealing the genetic factors involved in the fishy odor in duck eggs.

Genetic Variant in Flavin-Containing Monooxygenase 3 Alters Lipid Metabolism in Laying Hens in a Diet-Specific Manner

Genetic variant T329S in flavin-containing monooxygenase 3 (FMO3) impairs trimethylamine (TMA) metabolism in birds. The TMA metabolism that under complex genetic and dietary regulation, closely linked to cardiovascular disease risk. We determined whether the genetic defects in TMA metabolism may change other metabolic traits in birds, determined whether the genetic effects depend on diets, and to identify genes or gene pathways that underlie the metabolic alteration induced by genetic and diet factors. We used hens genotyped as FMO3 c.984 A>T as well as those with the homozygous normal genotype. For each genotype, hens were provided with either a corn-soybean meal basal diets (SM), which contains lower levels of TMA precursor, or the basal diets supplemented with 21% of rapeseed meal (RM), which contains higher levels of TMA precursor. An integrative analysis of metabolomic and transcriptomic was used to explore the metabolic patterns of FMO3 genetic variant in hens that were fed the two defined diets. In birds that consumed SM diets, the T329S mutation increased levels of plasma TMA and lipids, FMO3 mRNA levels, and the expression of genes involved in long chain polyunsaturated fatty acid biosynthesis. In birds that consumed RM diets, the T329S mutation induced fishy odor syndrome, a repression in LXR pathway and a reciprocal change in lipid metabolism. Variations in TMA and lipid metabolism were linked to the genetic variant in FMO3 in a diet-specific manner, which suggest FMO3 functions in TMA metabolism and lipid homeostasis. LXR pathway and polyunsaturated fatty acid metabolism are two possible mechanisms of FMO3 action in response to dietary TMA precursor.

The detection and elimination of flavin-containing monooxygenase 3 gene T329S mutation in the Beijing You chicken

In this study, using a newly developed TaqMan-based real-time PCR method for the T329S mutation in the flavin-containing monooxygenase 3 (FMO3) gene, a marker-assisted selective breeding program against the unfavorable T allele was implemented in the Beijing You chicken breeding stock from 2010 to 2012. A total of 2,359 breeder candidate chickens were detected. After 1-generation culling in both males and females and 2-generation culling only in males, genotyping results in 2013 showed that there still remained a low unfavorable allele frequency of 0.022 in this population. The results indicated that to ensure a complete eradication of the defective tainting mutation in FMO3 out of the Beijing You population, more strict breeding and management schemes should be carried out in the future.

Trimethylamine deposition in the egg yolk from laying hens with different FMO3 genotypes

The A/T polymorphism at position nt 1,034 of the chicken FMO3 cDNA sequence is associated with elevated levels of trimethylamine (TMA) in the egg yolk, which is responsible for the fishy egg flavor. This study was aimed to investigate yolk TMA deposition in eggs from different FMO3 genotype (AA, AT, TT) laying hens fed a high level of choline, and the relationship between egg yolk TMA contents and yolk acceptability. A total of 132 genotyped laying hens, 38 wk of age, were assigned to 1 of the 4 dietary treatments: 1) a control group of AA hens fed 370 mg of choline/kg of diet (practical choline level, provided by 500 mg of choline chloride/kg of diet); 2) AA hens were fed 2,960 mg of choline/kg of diet (higher dietary choline level, provided by 4,000 mg of choline chloride/kg of diet); 3) AT hens were fed 2,960 mg of choline/kg of diet; and 4) TT hens were fed 2,960 mg of choline/kg of diet. All layers were fed a 370 mg of choline/kg added diet for a period of 1-wk adaptation followed by a 6-wk trial period. A remarkable increase in yolk TMA concentration of TT hens (P < 0.001) caused by dietary choline addition at 2,960 mg/kg was observed. The relationship between TMA concentration in the egg yolk (μg/g, y) and deposition time (1~42 d, x) for TT hens is y = 0.0005x(3) - 0.0419x(2) + 1.0924x + 0.4323 (R(2) = 0.9259). The fish-flavor scores of egg yolks rose steadily (R(2) = 0.9324) as the TMA concentration increased, and there was also a corresponding decrease in the acceptance score (R(2) = 0.8276). The eggs were acceptable when the yolk TMA concentrations were less than 4.516 μg/g of yolk.