Genetic differences in oestrous signs and oestrogen metabolism‐related genes between Chinese Mi and European Landrace‐Large White pigs

Abstract

Oestrous signs affect timely mating and reproductive efficiency in swine breeding herds. To study the genetic difference of oestrous signs between Chinese and European pigs, 100 Landrace-Large White (LLW) cross gilts and 50 Chinese Mi gilts were assessed for oestrous signs and the concentrations of serum estradiol-17β and progesterone were determined. The genotype of 39 single nucleotide polymorphisms (SNPs) in 11 oestrogen metabolism and function-related genes was determined by Sequenom iPLEX platform. Compared with LLW gilts, Mi gilts had longer time of standing reflex (p < .001), higher scores of vulva reddening (p = .001) and greater serum estradiol-17β concentration (p < .01). Gilts with greater serum estradiol-17β concentrations also had greater (p < .05) scores for oestrous signs. Genetic polymorphisms of nine genes in oestrogen metabolism pathways had significant differences (p < .05) between LLW and Mi gilts. There were three and six haploblocks of SNPs in LLW and Mi, respectively. Compared with LLW, the distribution of haplotypes was more centralized in Mi pigs. Genetic polymorphisms of oestrogen metabolism-related genes have considerable differences between Chinese Mi and European LLW pigs. Because of the important roles of oestrogen during the oestrus, some genes of oestrogen metabolism pathway could be considered as candidate genes for oestrous signs.

Functional variants in the promoter region of sulfotransferase 1C1 gene associated with estrogen degradation in gilts

“…Therefore, the functional mutations of c. − 994 G > A and c. − 946 G > A sites would affect the binding of RNA polymerase or transcription factors, which could decrease the expression level of SULT1C1 gene. The down‐regulation of SULT1C1 protein would reduce the degradation of estrogen, which results in longer duration and clearer expression of estrus in Chinese Mi gilts (Chu, Liang, & Zhou, 2017) (supporting information Figure S1).…”

Identification of Functional Single Nucleotide Polymorphisms in Porcine HSD17B14 Gene Associated with Estrus Behavior Difference between Large White and Mi Gilts

“…Our previous studies found that Chinese Mi gilts had more intense estrus behaviors and greater estradiol-17β concentrations than Large White gilts [ 23 ]. The expression level of the porcine HSD17B14 gene was significantly different between the two stages of the estrus cycle and between the two pig breeds [ 24 ].…”

“…The identification of estrus behavior includes the color of the vulva, the color of vaginal mucus, the amount of mucus, the viscosity of mucus, vocalization of gilts, and climb across behavior. When a standing reflex occurred, the expression of estrus was scored (0: no; 1: weak; 2: strong) via the use of scoring criteria [ 23 ]. After the first scoring, Large White and Mi gilts with scores of 2 points were selected.…”

“…According to the scoring standard of estrus characteristics, at the onset of standing reflex in the second estrus cycle, a 5 mL sample of blood was collected from the anterior vena cava of gilts at the 10th day of the estrus cycle. Blood samples were centrifuged at 3000 rpm for 10 min, immediately after collection blood samples of Large white and Mi gilts were collected for estrogen determination [ 23 ]. Before the third estrus cycle, 6 Large white gilts and 6 Mi gilts were selected.…”

“…Gilts of these Chinese pig breeds reach puberty at an earlier age [ 22 ], express behavioral estrus for longer, and have slightly shorter estrus cycles [ 18 ]. Compared with Large White gilts, Mi gilts have a longer duration of standing reflex, greater scores of vulva reddening and greater serum estradiol-17β concentration [ 23 ].…”