Differential DNA methylation analysis reveals key genes in Chinese Qingyu and Landrace pigs

The Chinese Qingyu pig is a typical domestic fatty pig breed and an invaluable indigenous genetic resource in China. Compared with Landrace pig, Qingyu pig has unique meat characteristics, including muscle development, intramuscular fat, and other meat quality traits. At present, few studies have explored the epigenetic difference due to DNA methylation between Qingyu pig and Landrace pig. In this study, 30 Qingyu pigs and 31 Landrace pig were subjected to reduced representation bisulfite sequencing (RRBS). A genome wide differential DNA methylation analysis was conducted. Six genomic regions, including regions on sus scrofa chromosome (SSC) 1: 266.09-274.23Mb, SSC5:0.88-10.68Mb, SSC8:41.23-48.51Mb, SSC12:45.43-54.38Mb, SSC13:202.15-207.95Mb, and SSC14:126.43-139.85Mb, were regarded as key regions that may be associated with phenotypic differences between Qingyu pig and Landrace pig. Furthermore, according to the further analysis, 5 differential methylated genes (ADCY1, FUBP3, GRIN2B, KIT, and PIK3R6) were deemed as key candidate genes that might be associated with meat characteristics. Our findings provide new insights into the difference of DNA methylation between Qingyu pig and Landrace pig. The results enrich the epigenetic research of Chinese Qingyu pigs.

STUDY OF REPRODUCTIVE QUALITIES OF LANDRACE PIG LINES

The purpose of the research was to study the reproductive qualities of Landrace pig lines bred in JSC Rassvet in the period from 2015 to 2017. The productive qualities of pig lines were evaluated by the normal farrowing of sows and indicators of the reproductive qualities of boars. To assess the indicators of reproductive qualities of sows, the index ‒ J3 was developed, which includes the number of live piglets after farrowing, the weight of piglets at weaning, and the number of piglets at weaning. The indicators of the J3 index were adjusted for the alignment of the litter. The index of evaluation of indicators of reproductive qualities of boars, includes indicators of the index of commodity mass of the nest J3 for sows born with a boar and the percentage of fertilization of sows. It was found that the Landrace pig line of French origin has a higher multiplicity and the number of piglets at weaning, but lower milk content. The analysis of correlations of reproductive qualities of sows showed a significant influence of technological factors on the reliability of the assessment of breeding value and confirmed the need to use correction factors for the alignment of the litter.

ANALYSIS OF THE REPRODUCTIVE QUALITIES OF LANDRAS AND WALSH PIGS IN THE BREEDING ENTITIES OF UKRAINE

The analysis of the facilities for breeding for Landrace and Wales pigs in Ukraine was carried out; it was established that as of 01.01.2021 there were 16 breeding facilities for Landrace pigs in Ukraine. It identifies that in comparison to last year the number of facilities has decreased by one. Heterogeneity in geographical location was identified; so out of 25 regions (together with the ARC), 13 have breeding facilities for breeding Landrace pigs and in one region there is a breeding facility for breeding Walsh pigs. Accordingly, in 12 (together with the ARC) regions, there are no breeding facilities for both breeds. There is a disproportion in the number of boars and sows in some breeding facilities. So the average number of breeding stock at 1 breeding plant for Landrace pig breed is 350 heads. However, at the same time, in the Ternopil region within one breeding plant there are 1080 sows, and in the Mykolaiv region 70 heads. Assessment of the level of reproductive qualities of sows indicates the need for further improvement of these indicators in most farms. Thus, the analysis of the multiple fertility rate between the facilities for the Landrace breed proved that the difference between the farms with the smallest and largest fertility indicator is 9.1 heads or 206 %. It should be noted that in most farms this indicator is 11–12.3 heads. In terms of litter weight at 2 months, there is also a significant difference between the farms with the smallest and largest indicators and it is 141 kg or 187 %. Accordingly, the SIVYAS index in farms ranged from 76.5 to 147.1. Although in Ukraine there is only one farm for breeding pigs of the Welsh breed, the animals have rather high indicators of reproductive qualities. So the multiple fertility was 12.8 heads, the weight of the litter at 2 months was 210 kg, respectively, the SIVYAS index was 109.5.

BOAR SPERM SURVIVAL ABILITY IN DISTINCTORS OF DIFFERENTLY PRODUCED DISTILLED WATER

Testing and comparative evaluation of germ cells in boars of Landrace breed of different genotypes on qualitative and quantitative indicators, for further use in diluents of different distilled water, is carried out. Studies have shown that the quantitative and qualitative indicators of sperm production of French boars had the highest ejaculate volume and sperm count among other boars. Boars of domestic selection had the highest concentration of sperms, and boars of English selection prevailed in terms of motility. The results of research show that among the tested ejaculates the best sperm at a dilution of 1: 1 were found in boars of English Landrace pig breed, the absolute survival rate of which was (Sa) - 732.4 um. from according to the degree of rarefaction 1: 2 - 1: 3, the highest rate had ejaculates of boars of French selection, the studied indicator of which was (Sa) - 720.9 (Sa) - 708.8 um. from in accordance. The use of distilled water of foreign production has improved the survival rates of boar semen compared to distilled water of domestic production, which is produced directly at the artificial insemination point of the farm. Thus, according to this indicator, the semen of domestic boars lived 3.7 hours or 3.4% less than the semen of French boars and 8.8 hours or 5.3 % less than the semen of English boars. The thinning of semen in other degrees did not reveal a probable difference between boars. Analysis of these studies shows that the semen of boars of English selection prevailed on the studied indicator of semen of other boars when used in diluents of water of foreign, domestic and local production (obtained at the point of artificial insemination of the farm).

Comparative metabolomic analysis of caecal digesta between Jinhua pig and Landrace pig

The metabolic difference in caecal digesta between Jinhua pig and Landrace pig was compared. Twenty weaned piglets at 28 days of age, including ten Landrace pigs (a Western pig breed) and ten Jinhua pigs (a Chinese native pig breed), were randomly selected and allocated into two groups. The pigs were fed the same corn-soybean diet on the same pig farm. At the age of 240 days, all pigs of each group were slaughtered, the digesta in the caecum of the twenty pigs were collected for metabolomic analysis and determination of short-chain fatty acids (SCFAs). The results showed that a total of 56 different metabolites (22 metabolites named and 34 metabolites without identification) were detected in caecal digesta using a gas chromatography time-of-flight/mass spectrometry (GC-TOF-MS)-based metabolomic approach. Forty-six of the 56 metabolites were upregulated significantly (P < 0.05) in Landrace group compared with Jinhua group. The metabolic pathways with different impact value in which different metabolites were mainly involved were tyrosine metabolism, citrate cycle and steroid biosynthesis. In addition, we found that Landrace accumulated more SCFAs in caecal digesta, while the concentrations of acetic acid (P < 0.01) and butyric acid (P < 0.05) in caecal digesta of Jinhua pig were markedly lower than those of Landrace pig. Collectively, our study was the first to compare the metabolic difference in caecal digesta between Jinhua pig and Landrace pig using a metabolomics approach, which might be used as a potential metabolomics mechanism to research different breeds of pigs.