SELECTION OF SOWS BY GENETIC MARKERS AND BLUP INDEX

The authors conducted studies on the effect of the estrogen receptor (ESR), prolactin receptor (PRLR), and ryanodine receptor (RYR-1) genotypes on the breeding value of sows. Using the BLUP method, they evaluated the indicators of the large white, landrace, and Duroc breeds to develop a regional hybridization system in the pig industry of the Belgorod region. The research determined a significant influence of the “desirable” BB and AB genotypes of the ESR gene in large white sows and the “desirable” BB genotype of the RPLR gene in Landrace and Duroc sows on the maternal BLUP index.

Effect of ESR, FSHB and PRLR Genes on Sperm Traits of Landrace and Yorkshire Boars in the Tropical Environmental Conditions of Vietnam

Background: Fertility traits in pigs made a restricted progress through traditional selection. Applying marker assisted selection could improve these traits. The aim of the study was to investigate the effects of candidate genes Estrogen Receptor (ESR), Follicle Stimulating Hormone Beta (FSHB) and Prolactin Receptor (PRLR) on sperm quality traits of Landrace and Yorkshire boars under tropical conditions in Northern Vietnam.Methods: A total of 6306 ejaculates from 140 boars (92 Landrace and 48 Yorkshire) were collected to estimate sperm ejaculate volume (VOL), spermatozoon motility (MO), sperm concentration (CO) and total number of spermatozoon in ejaculate (NT). Ear tissue samples were collected for genotype identification of SNP present in ESR, FSHB and PRLR genes using PCR-RFLP technique. A mixed model was used to test the effect of different genetic and non-genetic factors on the sperm quality traits.Result: The genotype frequencies of ESR, FSHB and PRLR were in Hardy-Weinberg equilibrium for each breed. Age of boars and month of the year had significant effect on all the sperm quality traits (P less than 0.01) while effect of breed was found to be non-significant on all the sperm quality trait. FSHB gene significantly (P less than 0.05) affected VOL, MO and CO. Boars with BB genotype showed positive effect on VOL but negative effect on MO and CO in comparison with AA genotype boars. ESR gene showed only effect on VOL while PRLR affected only MO. Boars with AA and AB genotypes of ESR gene had a significantly higher VOL than those with BB genotype (P less than 0.05). For PRLR gen, AB genotype was associated with higher MO than AA genotype (P less than 0.05). These results suggest a possibility of using the existing polymorphisms in ESR, FSHB and PRLR genes to improve some sperm traits of Landrace and Yorkshire boars.

Herd specific effects of the ESR gene on litter size and production traits in Czech Large White sows

The effect of PvuII polymorphism of the oestrogen receptor gene on litter size and production traits in a Czech Large White population (882 sows, 2 455 litters) was evaluated. Data were analysed by four four-trait animal models. The traits analysed were lifetime average daily gain in the field test, lean meat percentage, number of piglets born alive in parity 1 and number of piglets born alive in parity 2 and subsequent parities. The animal models differed in considering the herd-year-season effect as random or fixed and in including or not including the dominance effect. For each model two variants were calculated: the ESR effects were calculated either across herds or within herds. On the genetic level, no significant overall effects of the ESR gene were detected. The effects of the ESR gene within herds were mostly insignificant as well. There was a certain tendency for allele A to increase litter size in parity 1. Nevertheless, on the basis of the present knowledge, the use of the ESR gene for selection for litter size in the Czech Large White breed seems to be of questionable benefit and cannot be recommended.  

Effect of the oestrogen receptor (ESR) gene on reproductive traits of Large White, White Meaty and Landrace pigs

We investigated the effect of oestrogen receptor (ESR) gene on total number of born (TNB), number of born alive (NBA) and number of weaned (NW) piglets in Large White (LW), White Meaty (WM) and Landrace (L) sows from six Slovak breeding farms. Detection of ESR (Pvu II) genotypes was performed by the PCR-RFLP method. The frequencies of favourable B allele in LW, WM and L were 0.33, 0.25 and 0.08, respectively. We found a highly significant effect of ESR locus on NW (P ≤ 0.01) in LW, however, we observed a negative effect of BB genotype on the trait. In WM, a positive association of B allele with TNB, NBA and NW was found but the differences were not confirmed statistically. A highly significant effect of ESR locus on TNB, NBA and NW (P ≤ 0.01) was identified only in L breed. We found an increase of +0.62 ± 0.18 (TNB), +0.65 ± 0.18 (NBA) and +0.51 ± 0.16 (NW) pigs per copy of B allele.  

Analysis of prolificacy in sows of hyperprolific lines of Large White breed

The objective of the paper was to evaluate the results of reproductive performance of sows in some elite breeding herds of the Large White breed included in experimental herds for the production of hyperprolific lines of dam breeds. The set consisted of 98 sows with the known genotypes of ESR, FSHâ and PRLR genes. The dendrogram shows that on the basis of their genetic outfit the sows can be divided into two clusters. The first cluster can be described as a cluster with marked dominance of HPL sows and the second cluster with marked dominance of the sows of basic herd. The first cluster consisted of individuals in which the preferred genotype AA of PRLR gene was not detected. As for FSHâ gene, the beneficial genotype BB was found out in 74.10% of sows. In ESR gene the beneficial genotype DD was recorded only in 11.10% of individuals. On average for the lifetime performance they delivered by 2.08 piglets more in all born piglets and by 1.96 piglets more in live-born piglets per litter. Differences in the reproductive traits between HPL sows and the sows of basic herd in the first cluster were statistically highly significant. On the contrary, genotype AA of PRLR gene was identified in all sows of the second cluster, 61.36% of animals possessed beneficial genotype BB of FSHâ gene. As for ESR gene, beneficial genotype DD was identified within the whole cluster in 31.82% of sows. In lifetime performance the HPL sows had on average by 1.10 individuals more in all born piglets and by 1.01 more in live-born piglets (statistically significantly higher values). The unambiguous expression of a positive effect of preferred genotypes of selected candidate genes failed to be confirmed by the results of statistical analyses testing the associations of candidate genes for pig reproduction with selected parameters of breeding value and prolificacy of sows.  

Role of genetic markers in the prediction of classification of Czech Large White gilts to a hyperprolific line

The objective of statistical evaluation (discriminant analysis) was to find out whether the genetic endowment the gilt was born with is a high-quality discriminator for prediction of its future classification to a hyperprolific line (HPL). Based on the results a conclusion is drawn that the gilt with genotype CC of ESR gene will be classified to HPL in high probability – if the effect of this gene is not reduced by an interaction with other genes. The statistical analysis did not reveal a significant effect of FSHB gene in Czech Large White sows on their future classification to HPL. On the contrary, PRLR gene is a highquality discriminator. Obviously, it is highly probable that the gilt with genotype BB will be classified to HPL. It is to state from the analysis of pairs of the studied genes that the adult gilt with genotype CC of ESR gene and genotype BB of FSHB gene and/or PRLR gene will be classified to HPL in all probability. PRLR gene has a dominant effect in the pair ESR and PRLR. Genotype BB of PRLR gene (the most beneficial of the genotypes from the aspect of future classification of gilts to HPL) markedly increases posterior probability of alleles of ESR gene. If the classification of a gilt to HPL is predicted from the analysis of all three genes, the results of partial analyses are confirmed in most cases. The results of the experiment indicate a possible prediction of gilts on the basis of their genotype for classification to HPL but it cannot be confirmed that the identified »beneficial« genotype will always be expressed in different populations by an increase in reproductive traits.