Detection of novel single-nucleotide polymorphisms (SNPs) in the CYP21 gene and association analysis of two SNPs for CYP21 and ESR2 with litter size in a commercial sow population

Altogether 129 F₁ sows from a commercial sow farm with at least four litters were genotyped for the oestrogen receptor 2 gene (ESR2) and cytochrome P450 hydroxylase 21 gene (CYP21) and investigated for associations on the litter‐size parameters: total number born and number born alive. Five novel polymorphisms were found in the 3′‐untranslated region for the CYP21 gene. Genotype and allele frequencies for the CYP21 (position 3462G > A) single‐nucleotide polymorphism (SNP) were 0.434 (GG), 0.504 (AG), 0.062 (AA) and 0.69 (G):0.31 (A), respectively. No association was found between this polymorphism and litter‐size parameters. For the ESR2 gene, the SNP in exon 5 associated with an amino acid substitution MET (allele A) > VAL (allele G) was investigated. Only two genotypes were found leading to allele frequencies of 0.34 (A):0.66 (G). Only number born alive piglets were significantly increased for the AG genotype (p = 0.034) with 11.64 piglets per sow and litter in comparison with the GG genotype, leading to only 10.96 piglets per sow and litter. From these data, it can be concluded that the investigated SNP of the ESR2 gene is associated with the number of liveborn piglets in the commercial population considered, and hence could be useful in selection for litter size. Therefore, this gene should be investigated in additional populations.     

ESR基因多态性对不同胎次的大白猪母猪产活仔数的影响

为了研究ESR基因对大白猪经产母猪整个生产周期的影响并应用于猪繁殖性状改良,试验检测了该基因在472头大白猪经产母猪中的多态性分布,并根据基因分型结果分析了不同基因型对该群体1774胎产活仔数的影响。结果表明,AA、AB、BB基因型频率为0.206、0.572、0.222,AB基因型为优势基因型;A、B基因频率为0.493、0.507,B等位基因为优势等位基因。通过对不同胎次的分析发现,头胎AB基因型个体的产活仔数高于AA、BB基因型个体;2胎BB基因型个体的产活仔数高于AA、AB基因型个体;3胎AB、BB基因型个体的产活仔数高于AA基因型个体;4～7胎AA基因型个体的产活仔数最多（5胎除外）,8胎及以上胎次AB基因型个体的产活仔数最多,呈现一定的规律性,但是各胎次内的差异均不显著。     

Analysis of properdin (BF) genotypes associated with litter size in a commercial pig cross population

Properdin (BF) was investigated as a candidate gene influencing litter size in a commercial pig cross population. The BF gene was chosen because of its integral role in influencing uterine epithelium growth and because several quantitative trait loci (QTL) with impact on reproductive traits have been detected near the centromere of porcine chromosome 7. A total of 123 F₂ (Large White × Landrace) × Leicoma sows were genotyped using polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method. The sows were divided into two extreme performance groups, one with a high litter size (n = 61, ≥14.3 piglets per litter) and the other with a low litter size (n = 62, ≤11.3 piglets per litter). Although genotype and allele frequencies were uneven with 2.4% (AA), 16.3% (AB), 81.3% (BB) and 0.11 (A): 0.89 (B), the allele A was the unfavourable one, leading to less offspring. With regard to the level of significance at p < 0.05, the total number of born (TNB) and number of born alive (NBA) piglets were associated with BF genotypes. The genotype AA led to 10.55 TNB and 10.00 NBA, whereas the genotype BB led to 13.19 TNB and 12.11 NBA. The genotype AB was intermediate. In future, a systematic mating test is necessary in order to obtain more balanced genotype frequencies. Furthermore, it should be taken into consideration that the investigated polymorphism is located in an intronic region and the causative mutation is not clear yet.     

Oestrogen receptor genotypes and litter size in Hungarian Large White pigs

A total of 869 litter records of 226 Hungarian Large White sows have been analysed to investigate the possible use of the oestrogen receptor gene (ESR) as marker to improve litter size. First, second and later parities have been evaluated separately. Frequencies of A = 0.55 and B =0.45 have been calculated for the two ESR alleles and the observed/expected number of the three genotypes were as follows: AA: 71/69.1, AB: 108/111.8 and BB: 47/45.1. BB type first and later parity sows were superior to AB and AA sows for number born alive (NBA), total number of born (TNB) and the corrected number of weaned piglets (CNW), respectively.     

4个猪繁殖性状候选基因对大白猪产活仔数的影响

为研究猪繁殖性状候选主效基因的遗传效应并应用于猪的繁殖性状改良,实验选择472头大白能繁母猪作为基础群,检测4个控制猪繁殖性状的候选主效基因ESR、FSHβ、PRLR和RBP4在该群体的多态性分布及其对产活仔数的影响.结果表明:除RBP4基因为AA纯合子外,ESR、PSHIS、PRLR 3个基因均存在不同程度的多态,并...     

RYRl基因对母猪繁殖性能的影响

用 PCR- RFL P法检测 2 2 5头大约克母猪的 RYR1(ryanodine receptor,RYR1)基因 ,它具有 NN、Nn和 nn3种基因型 ,其频率分别为 0 .76、0 .14和 0 .10 ;等位基因 N和 n的基因频率分别为 0 .83和 0 .17。该基因处于遗传不平衡状态 (P<0 .0 1)。具有 NN、Nn和 nn基因型母猪第 1胎产仔数分别为 10 .2 1、9.6 2和 8.2 2头 ;断奶仔猪数分别为9.2 1、8.13和 7.11头。等位基因 n使仔猪断奶应激效应具上升趋势 ,对增重有不利影响 ;降低母猪的产仔数和仔猪成活率 ,对繁殖性能有不良的遗传效应 ,有必要从母猪群中清除该等位基因。     

Impact of RYR1 genotype of Piétrain boars on litter traits of Czech Large White × Czech Landrace crossbred sows

Summary Piétrain boars of different ryanodine receptor (RYR1) genotypes (NN, Nn and nn, three boars each) were mated with approximately 10 Czech Large White × Czech Landrace sows (genotype NN) each to produce one litter per sow. The progeny of nn boars had a significantly higher individual weaning weight (7.31 kg versus 6.86 kg) and average daily gain from birth to weaning (252 g/day versus 240 g/day) than the progeny of NN boars. Furthermore, piglets from nn boars differed statistically significant also from piglets of boars with the Nn genotype for these two traits. The litters of the NN boars were greater by 0.5 piglets than the litters of the nn boars for the total number of piglets born, piglets born alive and piglets weaned, but the differences were not significant. The Nn genotype showed for all litter size traits and the number of stillborn piglets the best values. The difference between the genotypes Nn and nn was statistically significant at the 0.05 level for the number of piglets born alive and the number of piglets weaned.     

猪PRLR和FSHβ基因多态性检测及其与繁殖性状的关联分析

试验旨在研究催乳素受体（prolactin receptor,PRLR）和卵泡刺激素β（follicle-stimulating hormone β,FSHβ）基因的多态性及其与母猪繁殖性状的关联分析。采用PCR-RFLP方法对大白猪、杜洛克猪和长白猪3个猪种共487头母猪进行了PRLR和FSHβ基因多态性检验,并采用单因子方差分析、LSD法分析不同基因型与母猪总产仔数、产活仔数、断奶窝重和断奶窝仔数等繁殖性状的相关性。结果表明,PRLR基因在大白猪和长白猪中B等位基因均为优势基因,基因频率分别为0.717和0.548,大白猪BB基因型总产仔数显著高于AA基因型（P<0.05）,长白猪BB基因型断奶窝重显著高于AB基因型（P<0.05）;FSHβ基因在大白猪、杜洛克猪和长白猪3个猪种中B等位基因均为优势基因,基因频率分别为0.804、0.760和0.789,长白猪BB基因型总产仔数和产活仔数均显著高于AB基因型（P<0.05）,呈现BB>AA>AB趋势。因此,PRLR和FSHβ基因对荣昌猪场母猪繁殖性能有一定影响,可作为母猪繁殖性能分子选育的候选参考基因。     

Effect of the polymorphism of prolactin receptor (PRLR) and leptin (LEP) genes on litter size in Polish pigs

The aim of the experiment was to use the DNA mutations in the PRLR and LEP genes to determine associations between the genotype and litter size in Polish Large White × Landrace sows. Reproductive traits investigated were: total number of piglets born (TNB), number of piglets born alive (NBA) and number of piglets weaned. The polymorphism in PRLR and LEP genes was detected using the polymerase chain reaction–restriction fragment‐length polymorphism (PCR‐RFLP) method, with specific primers and the restriction enzymes AluI and HinfI respectively. Two different alleles of PRLR and LEP gene were identified: alleles A (0.62) and B (0.38) of the PRLR gene and alleles C (0.10) and T (0.90) of the LEP gene. The relationships between the PRLR and LEP genotypes and TBN, NBA and NW were analysed. The analysis showed, in first parity sows, statistically significant (p ≤ 0.01) differences between sows carrying different PRLR genotypes. In later parities, sows with the AA genotype still had the largest litter size compared with AB and BB sows, but the difference was statistically not significant. Analysis of the interaction PARITY × PRLR showed small and statistically not significant differences. The analysis of relationship between different LEP genotypes and TNB, NBA, NW showed small and statistically non‐significant differences.     

Genetic variation at the alpha‐1‐fucosyltransferase (FUT1) gene in Asian wild boar and Chinese and Western commercial pig breeds

Escherichia coli F18 bacteria producing enterotoxins and/or shigatoxin (ETEC/STEC) are main pathogens that cause oedema disease and postweaning diarrhoea in piglets, and alpha‐1‐fucosyltransferase (FUT1) gene has been identified as a candidate gene for controlling the expression of ETEC F18 receptor. The genetic variations at nucleotide position 307 in open reading frame of FUT1 gene in one wild boar breed and 20 western commercial and Chinese native pig breeds were investigated by polymerase chain reaction–restriction fragment length polymorphism. The results showed that the genetic polymorphisms of the FUT1 locus were only detected in western pig breeds and the Chinese Taihu (including Meishan pig, Fengjing pig and Erhualian pig), Huai and Lingao pig breeds; only Duroc and Pietrain possessed the resistant AA genotype, while the wild boar and other Chinese pig breeds only presented the susceptible genotype GG. The results indicated that Chinese native pig breeds lack genetic factors providing resistance to ETEC F18 bacteria. The resistant allele to ETEC F18 might originate from European wild boar. It was inferred that oedema and postweaning diarrhoea caused by ETEC F18 have close relationship with the growth rate, which can explain why on the contrary Chinese native pig breeds have stronger resistance to oedema and postweaning diarrhoea in piglets compared with western pig breeds.     

Candidate gene markers for litter size in different German pig lines.

Three diallelic RFLP markers at candidate gene loci for litter size, the estrogen receptor (ESR) gene, the prolactin receptor (PRLR) gene, and the retinol-binding protein 4 (RBP4) gene, were evaluated for their association with the number of piglets born alive in different German pig lines. Genotyping was performed on boars and sows belonging to three different genetic groups from a single farm. Information on 8,336 litter records from 2,159 sows (German Landrace, n = 1,672; Duroc, n = 214; and a synthetic line, n = 273) was used in the analyses with respect to litter size. Growth performance traits were only analyzed for the synthetic line. The ESR locus showed no polymorphism in the tested boars of the German Landrace and Duroc lines. In the synthetic line, the frequency for the A allele was 0.90 and no homozygous BB animal was detected. No significant associations of ESR alleles with number of piglets born alive, backfat thickness, or average daily gain were observed. A new PCR-RFLP was developed for testing the PRLR polymorphism. The frequencies of PRLR allele A were 0.40 in the German Landrace, 0.49 in the synthetic, and 0.82 in the Duroc line. In the Duroc line, a small additive effect of the allele B on litter size was observed. The allelic substitution effect was 0.71 piglets born alive across all parities (P = 0.05). No significant associations of the PRLR locus with litter and growth performance traits were detected. The frequencies of RBP4 allele A ranged from 0.62 in the synthetic line to 0.67 in the German Landrace to 0.85 in the Duroc line. For the genotyped sows of the synthetic line, there was no indication of a favorable effect of the A allele with respect to litter size. Results of this study demonstrate that allele effects differ between lines or populations. This may be due to possible different linkage phases between the marker alleles and the causal mutations in the different lines. The results may also be explained by many minor genes affecting litter size. A selection strategy should be designed for each line separately and should always consider possible pleiotropic effects.     

Effects of prolactin receptor genotype on the litter size of Mangalica

The aim of this study was to detect different alleles of the prolactin receptor (PRLR) gene and to examine their effects on the litter size of the indigenous Hungarian pig, the Mangalica. G1789A single nucleotide polymorphism (SNP) was investigated as a candidate for litter size. Samples from 80 purebred Mangalica sows and data of their 335 litters were provided by Olmos & Tóth Ltd. Hair follicles were used to isolate the required DNA. Allelic discrimination was performed by means of the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method using the AluI restriction enzyme and agarose gel electrophoresis. In the population examined, the A allele was found to be preferable in the Mangalica breed group. The most advantageous AA genotype was the least prevalent (8.75%), while the frequencies of AB and BB were 40% and 51.25%, respectively. Remarkably, the average number of piglets born alive per litter was 1.11 ± 0.39 higher in sows with AA as compared to those with BB genotype. By raising the frequency of the AA genotype, the litter size is likely to increase. However, the effect of PRLR genotypes can differ among pig breeds and even lines. Further studies may be required to observe and estimate possible pleiotropic effects of this polymorphism on other traits.     

淮猪新品系FSH β亚基基因多态性及其与产仔数的相关性研究

在212头淮猪新品系母猪群中进行FSH β亚基基因多态性及其与头胎产仔数性状的相关性分析,结果表明,在淮猪新品系母猪群中,FSH β亚基基因的A等位基因为优势等位基因,其基因频率为0.6085。在淮猪新品系母猪头胎产仔数性状上,FSH β亚基基因的AA基因型为有利基因型,AA型的头胎总产仔数比BB型高1.47头（P<0.01）,AA型的头胎产活仔数比BB型高1.15头（P<0.05）。     

Experimental production of congenital persistent swine fever infections: I. Clinical,pathological and virological observations

Twelve sows were inoculated with a low-virulent field strain of swine fever (SF) virus at 40, 65 and 90 days of pregnancy. Transplacental infection occurred in eight sows and these farrowed 88 piglets.Prenatal mortality was highest in litters from sows infected at 40 days after service, and postnatal death was most frequent in litters from sows infected at 65 days. Three sows gave birth to completely infected litters, whereas the five others farrowed litters in which uninfected piglets were found. The later the sows were infected during pregnancy, the more uninfected piglets were born. Twelve piglets recovered from the infection and the percentage of recoveries increased with the stage of pregnancy at which inoculation took place. Twenty-three piglets developed a persistent infection. The earlier infection occurred during pregnancy, the more persistent infections were produced. The persistently infected pigs developed a runting syndrome from about one week after weaning. The clinical signs were more severe in pigs from sows infected at 65 days of pregnancy than in pigs from sows infected at 40 days. A persistent viraemia was present in these pigs with titres ranging between 10^5.7 and 10^7.0 plaque forming units/ml of plasma. At autopsy the most pronounced lesions were an atrophy of the thymus, and swollen and pale lymph nodes. Virus antigen was present in lymphoidal, reticulo-endothelial and epithelial tissues.One persistently infected pig survived superinfection with a virulent strain of SF virus for 45 days.     

PRLR、RBP4基因多态性分布及其对大白猪产仔数的影响

为了研究猪繁殖性状候选主效基因PRLR、RBP4多态性在大白猪群中的遗传效应,并应用于遗传改良,试验检测了278头大白母猪的基因多态性分布,分析了2个基因多态性位点不同基因型与该群体1418胎总产仔数和产活仔数的遗传效应。结果表明,PRLR基因位点上优势等位基因为B,其频率为0.538;头胎、二胎和所有胎次各基因型母猪的总产仔数大小均为BBABAA,经产胎次各基因型母猪则为ABBBAA,但均没有显著差异,产活仔数的分析也得到了相似的结果;RBP4基因位点在该群体中均为AA型纯合子。     

Farrowing hut design and sow genotype (Camborough-15 vs 25% Meishan) effects on outdoor sow and litter productivity

Performance measures were evaluated for 125 outdoor sows and litters of two crossbred genotypes (Camborough-15 and 25% Meishan) and in two farrowing hut designs (American-style and English-style hut). Contemporary breeding groups of second-parity sows were evaluated in an intensive, outdoor research unit. Sow genotype and hut designs were arranged factorially. Seven complete blocks were evaluated over a 21-wk period. No interactions between environment and genotype were identified for sow and litter productivity. Litters farrowing in the English-style huts weaned 1.5 more (P < .05) piglets per sow (because of a lower preweaning mortality, P = .05) than did litters in the American-style huts. The 25% Meishan weaned 1.7 more (P < .01) pigs per sow than Camborough-15, because of a greater number of piglets born alive. The effects of hut style and genotype were additive and 25% Meishan sows in English-style huts weaned an average (+/- SEM) of 11.1 +/- .83 piglets per sow. The English-style arc hut design may improve outdoor pig production and increase competitiveness of the intensive, outdoor system. The 25% Meishan genotype has potential for increased pigs weaned per litter that must be considered in light of other features of this genotype such as body composition.     

Evaluation of reproductive traits and ovarian and uterine morphology of sows with different genotypes for the estrogen receptor,prolactin receptor,and follicle-stimulating hormone subunit beta genes

The purpose of this study was to analyze the morpho-functional features of the ovaries and uterus of sows with different genotypes for the estrogen receptor (ESR), prolactin receptor (PRLR), and follicle-stimulating hormone subunit beta (FSHβ) genes associated with reproductive traits. Healthy Large White sows were studied. The genotypic status of the ESR, PRLR, and FSHβ genes was detected by polymerase chain reaction-restriction fragment length polymorphism. The structure of the ovaries and uterus was studied using quantitative assessment of organs and histological research.Sows with the ESR^BB genotype significantly exceeded animals with the ESR^AA genotype in milk yield (by 0.3 kg) and in the number of piglets at birth (by 0.9 animals) and at weaning (by 0.7 animals). Sows with the ESR^AB genotype were midway between those with ESR^BB and ESR^AA genotypes in terms of these reproductive traits. Animals with the PRLR^AA genotype significantly exceeded those with the PRLR^BB genotype in the number of piglets born (P < 0.05); the differences in litter weight at birth were not significant. Compared to other genotypes, sows with genotypes ESR^BB (P < 0.05) and PRLR^{AA (AB)} (P < 0.05) had larger uteruses and more yellow bodies, tertiary follicles, and primordial follicles in their ovaries. Animals with the FSHβ^BB genotype significantly exceeded animals with the FSHβ^AB genotype in the length of uterus by 21 cm (P < 0.05).     

FSHβ基因的多态性分布及其对大白猪产活仔数的影响

为了研究猪繁殖性状候选主效基因FSHβ在大白猪不同胎次中的遗传效应,并应用于大白猪繁殖性状的遗传改良,采用PCR方法检测了该基因在2个大白猪育种群共802头母猪中的多态性分布,并分析了其对产活仔数的影响,其中湖北天种公司大白猪群体样本数为472头,分析统计胎次1774胎,等位基因A的频率为0.447、等位基因B的频率为0.553;宜昌正大公司大白猪群为330头,分析统计胎次1644胎,等位基因A、B的频率分别为0.312、0.688。分析该位点的多态性与产活仔数的关系,结果发现,头胎不同基因型对产活仔数的影响为ABBBAA,二胎为AAABBB,经产胎次和所有胎次均为ABAABB,但差异均不显著。综合分析结果表明,A等位基因对大白猪产活仔数的影响要优于B等位基因,AB基因型母猪的产活仔数要优于其他2种基因型,提高生产猪群该基因的杂合子个体数比例有望取得更大的经济效益。     

Variability of piglet birth weights: A systematic review and meta-analysis

The objective of the study was to evaluate the effects of litter size and supplementation of functional amino acids on the piglet birth weight variability through of a systematic review and meta-analysis. PubMed, ISI Web of Science, Science Direct, Scopus and SciELO are the main used databases and were searched in January 2019 by using the following keywords and their combinations: within-litter birth, weight variability, piglets, litter size, sow, amino acids, gestation, uniformity, CV and/or SD. Of the 64 pre-selected articles, only articles presenting the coefficients of variation and/or standard deviations according to the litter size and different levels of amino acid supplementation in the sow diets during gestation were selected. The average birth weights of total and live piglets were 43% lower in litters from sows with high prolificacy than those from sows with low prolificacy. The weight variability was affected by high prolificacy sows, with increases of 4.04% and 4.54% in the coefficients of variation of total and born alive piglets respectively (p = .074; p = .009). The standard deviation increased by 180 g in born alive piglets to high prolificacy sows. The coefficients of variation of total and live piglets born from high prolificacy sows showed an increase of 4.04% and 4.54% respectively (p = .07; p < .05). There was a tendency for reduced weight variability with amino acids supplementation when considering the standard deviation of total born (p = .072). However, reproductive performance was not significantly influenced (p > .05). In conclusion, the average litter weight and the number of piglets born influence weight variability. Amino acids supplementation may reduce the birth weight variability between piglets. However, this effect depends on the amino acid used, the levels of supplementation and on other factors not completely addressed in this study. Thus, more research is necessary to fully elucidate this topic.     

Effect of intramuscularly administered beta-carotene on reproductive performance in sows

The present study investigated the effects of intramuscularly administered beta-carotene on reproductive parameters in female pigs. A total of 216 multiparous sows were observed from weaning of their litters until the next farrowing. On the day of weaning, the animals were allocated to two groups. Sows of the treatment group were injected with 70 mg beta-carotene both at the day of weaning and after the last insemination, sows of the control group were left untreated. For all sows, intramuscular injection of beta-carotene resulted in a significant increase of the total number of piglets born per litter by 1.2 (p < 0.05). When sows were divided by parity, beta-carotene treatment in second parity sows increased the total number of piglets per litter (beta-carotene 13.7 +/- 1.2, control 11.2 +/- 3.7, p < 0.01) and the number of piglets born alive (beta-carotene 12.0 +/- 2.7, control 10.0 +/- 3.4, p < 0.05). No such effect was seen in sows of third or higher parity. No other reproductive parameters were affected by beta-carotene supplementation. Tolerability and safety of the administered preparation were good. No side effects related to the medication were observed. The effect of beta-carotene on reproduction is thus affected by parity of the sows. This effect seems to be exerted mainly during early pregnancy and is most likely beta-carotene-specific and independent from its role as a vitamin A precursor.