Vertnin (VRTN) is involved in the variation of vertebral number in pigs and it is located on Sus scrofa chromosome 7. Vertebral number is related to body size in pigs, and many reports have suggested presence of an association between body length (BL) and meat production traits. Therefore, we analyzed the relationship between the VRTN genotype and the production and body composition traits in purebred Duroc pigs. Intramuscular fat content (IMF) in the Longissimus muscle was significantly associated with the VRTN genotype. The mean IMF of individuals with the wild-type genotype (Wt/Wt) (5.22%) was greater than that of individuals with the Wt/Q (4.99%) and Q/Q genotypes (4.79%). In addition, a best linear unbiased predictor of multiple traits animal model showed that the Wt allele had a positive effect on the IMF breeding value. No associations were observed between the VRTN genotype and other production traits. The VRTN genotype was related to BL. The Q/Q genotype individuals (100.0 cm) were longer than individuals with the Wt/Q (99.5 cm) and Wt/Wt genotypes (98.9 cm). These results suggest that in addition to the maintenance of an appropriate backfat thickness value, VRTN has the potential to act as a genetic marker of IMF.
BackgroundHamiltonian Monte Carlo is one of the algorithms of the Markov chain Monte Carlo method that uses Hamiltonian dynamics to propose samples that follow a target distribution. The method can avoid the random walk behavior to achieve a more effective and consistent exploration of the probability space and sensitivity to correlated parameters, which are shortcomings that plague many Markov chain Monte Carlo methods. However, the performance of Hamiltonian Monte Carlo is highly sensitive to two hyperparameters. The No-U-Turn Sampler, an extension of Hamiltonian Monte Carlo, was recently introduced to automate the tuning of these hyperparameters. Thus, this study compared the performances of Gibbs sampling, Hamiltonian Monte Carlo, and the No-U-Turn Sampler for estimating genetic parameters and breeding values as well as sampling qualities in both simulated and real pig data. For all datasets, we used a pedigree-based univariate linear mixed model.ResultsFor all datasets, the No-U-Turn Sampler and Gibbs sampling performed comparably regarding the estimation of heritabilities and accuracies of breeding values. Compared with Gibbs sampling, the estimates of effective sample sizes for simulated and pig data with the No-U-Turn Sampler were 3.2 to 22.6 and 3.5 to 5.9 times larger, respectively. Autocorrelations decreased more quickly with the No-U-Turn Sampler than with Gibbs sampling. When true heritability was low in the simulated data, the skewness of the marginal posterior distributions with the No-U-Turn Sampler was smaller than that with Gibbs sampling. The performance of Hamiltonian Monte Carlo for sampling quality was inferior to that of No-U-Turn Sampler in the simulated data. Moreover, Hamiltonian Monte Carlo could not estimate genetic parameters because of difficulties with the hyperparameter settings with pig data.ConclusionsThe No-U-Turn Sampler is a promising sampling method for animal breeding because of its good sampling qualities: large effective sample sizes, low autocorrelations, and low skewness of marginal posterior distributions, particularly when heritability is low. Meanwhile, Hamiltonian Monte Carlo failed to converge with a simple univariate model for pig data. Thus, it might be difficult to use Hamiltonian Monte Carlo for usual complex models in animal breeding.
Because of increasing litter size in Western pig breeds, additional teats are desirable to increase the capacity for nursing offspring. We applied genome-wide SNP markers to detect QTL regions that affect teat number in a Duroc population. We phenotyped 1024 animals for total teat number. A total of 36 588 SNPs on autosomes were used in the analysis. The estimated heritability for teat number was 0.34 ± 0.05 on the basis of a genomic relationship matrix constructed from all SNP markers. Using a BayesC method, we identified a total of 18 QTL regions that affected teat number in Duroc pigs; 9 of the 18 regions were newly detected.
BackgroundThe fatty acid (FA) composition of adipose tissue influences the nutritional quality of meat products. The unsaturation level of FAs is determined by fatty acid desaturases such as stearoyl-CoA desaturases (SCDs), which are under control of the transcription factor sterol regulatory element-binding protein (SREBP). Differences in SCD genotype may thus confer variations in lipid metabolism and FA content among cattle breeds. This study investigated correlations between FA composition and lipogenic gene expression levels in the subcutaneous adipose tissue of beef cattle breeds of different gender from the Basque region of northern Spain. Pirenaica is the most important beef cattle breed in northern Spain, while Salers cattle and Holstein-Friesian cull cows are also an integral part of the regional beef supply.ResultsPirenaica heifers showed higher monounsaturated FA (MUFA) and conjugated linoleic acid (CLA) contents in subcutaneous adipose tissue than other breeds (P < 0.001). Alternatively, Salers bulls produced the highest oleic acid content, followed by Pirenaica heifers (P < 0.001). There was substantial variability in SCD gene expression among breeds, consistent with these differences in MUFA and CLA content. Correlations between SCD1 expression and most FA desaturation indexes (DIs) were positive in Salers (P < 0.05) and Pirenaica bulls, while, in general, SCD5 expression showed few significant correlations with DIs. There was a significant linear correlation between SCD1 and SRBEP1 in all breeds, suggesting strong regulation of SCD1 expression by SRBEP1. Pirenaica heifers showed a stronger correlation between SCD1 and SREBP1 than Pirenaica bulls. We also observed a opposite relationship between SCD1 and SCD5 expression levels and opposite associations of isoform expression levels with the ∆9 desaturation indexes.ConclusionsThese results suggest that the relationships between FA composition and lipogenic gene expression are influenced by breed and sex. The opposite relationship between SCD isoforms suggests a compensatory regulation of total SCD activity, while opposite relationships between SCD isoforms and desaturation indexes, specially 9c-14:1 DI, previously reported as an indicator of SCD activity, may reflect distinct activities of SCD1 and SCD5 in regulation of FA content. These findings may be useful for beef/dairy breeding and feeding programs to supply nutritionally favorable products.
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