Polymorphism of mitochondrial tRNA genes associated with the number of pigs born alive

Background: Mutations in mitochondrial tRNA genes have been widely reported association with human reproductions.It is also important to explore the effect on the number of piglets born alive(NBA).Here,1017 sows were used to investigate the association between polymorphisms in mitochondrial tRNA genes and NBA.Results: In total,16 mutations were found in mitochondrial tRNA genes,of which 13 mutations were significantly associated with NBA(P < 0.05).The reproductions of mutant carriers were significantly greater than that of wild carriers by 0.989 piglets born alive/sow farrowing.To test whether the mutations altered the structure of mitochondrial tRNAs,the secondary and tertiary structures were predicted.In result,C2255 T changed the secondary structure of t RNA-Val by elongating the T stem and shrinking the T loop,and C2255 T and G2259 A in the tRNA-Val gene,C6217 T and T6219 C in the tRNA-Ala gene,and T15283 C in the tRNA-Glu gene altered the tertiary structure of their tRNAs,respectively by changing the folding form of the T arm,and C16487 T in the tRNA-Thr gene changed the tertiary structure of mitochondrial tRNA-Thr by influencing the folding form of the acceptor arm.Conclusions: Results highlight the effect of mitochondrial tRNA genes on the number of piglets born alive,and suggest that polymorphic sites of the tRNA genes be genetic markers for selection of pig reproduction.

Removal of roosters alters the domestic phenotype and microbial and genetic profile of hens

Hens are raised apart from roosters in modern poultry production, a substantial change from their natural social structure. We compared productivity, injuries, behavior, physiology, microbiome and transcriptome of hens housed with(R+) or without(R–)roosters to quantify the effects of this change in social structure. Hens were raised free-range from 70 to 280 days when 30 birds per treatment were assigned to battery cages until Day 315(R+C vs. R–C), while 30 birds per treatment remained in free-range pens(R+F vs. R–F). Response to a novel environment and object, behavioral time budgets, cecum microbiome, blood composition and transcriptomic sequencing of thigh muscle and spleen were analyzed. Hens housed without roosters showed better survival, consumed less food, produced more eggs and had better feed conversion. R+F hens clustered around the rooster and were less mobile in the novel environment and object tests. R+F hens displayed the richest microbiome, and the presence of roosters resulted in differentially expressed genes related to muscle development, cellular processes, environmental information processing and immune function. Removing roosters from housed hens intensified desirable characteristics favored by domestication probably operating by deprivation of mating behavior and reduced fear, along with altered microbial and genetic function.