Association of BF,RBP4, and ESR2 Genotypes with Litter Size in an Autochthonous Pig Population

The aim of the present study was to determine any potential association of the BF, RBP4, and ESR2 genes with reproduction traits in an autochthonous Greek pig population. The PCR-RFLP methodology was implemented for genotyping purposes of the examined genes. No deviation from the Hardy-Weinberg equilibrium was observed for the examined loci, while the B allele noted to be the more frequent in all analyzed genes. In addition, sows with the AA genotype of BF gene found to produce significantly lower numbers of the total born piglets (TNB) and number of piglets born alive (TNA), while the respective BB genotype significantly exceeded in TNB and NBA traits compared to the other two genotypes (P?Abbreviations: TNB: Total number of born piglets; NBA: Number of piglets born alive     

北京黑猪FSHb 亚基基因的多态性与繁殖性状的关联分析

本研究以北京黑猪为研究对象, 以FSHb 亚基基因为产仔性状的候选基因, 分别采用PCR产物直接电泳和PCR-RFLP方法来检测FSHβ亚基基因2个位点的多态性。结合测序发现: FSHb-1位点上, 北京黑猪BB型的134与135 bp (D00621序列的6 473与6 474 bp) 之间插入273 bp的片段而产生多态, 序列分析表明该插入片段为一典型的逆转座子, 在插入片段中还发现了一个RNA 聚合酶Ⅲ内部启动子; FSHb-2位点上, 由于扩增片段173 bp处存在C→T的突变, 使得HaeⅢ酶切位点消失而产生多态; 2个位点的A、B等位基因在北京黑猪群体中都有分布, 且处于低度多态。χ2适合性检验结果表明, 该群体在这2个位点的突变都达到Hardy-Weinberg平衡状态 (P>0.05)。用SAS 8.2 软件最小二乘法拟合线性模型, 将基因座不同基因型与繁殖性状总产仔数 (TNB)、产活仔数 (NBA) 和出生重 (WB) 进行了关联分析, 结果表明: 就初产母猪而言, FSHb-1位点上, AA型比AB和BB型个体的TNB分别多0.96头和1.85头 (P＜0.05), AA和AB型比BB型个体的NBA分别多0.95头和1.69头(P＜0.05)。FSHb-2位点上, AA型比AB型和BB型个体的TNB分别多1.57头和2.15头 (P＜0.05); AA和AB型比BB型个体的NBA分别多1.00头和0.94头 (P＜0.05); 就经产母猪而言, FSHb-2位点上, AA型个体的WB比BB型的WB重0.25 kg (P＜0.05)。全部群体的FSHb-1位点的A等位基因和初产母猪FSHb-2位点的A等位基因对TNB、NBA和WB表现为正效应。     

Effect of polymorphism in the peroxisome proliferator-activated receptor gamma gene on litter size of pigs

The association of polymorphisms in peroxisome proliferator-activated receptor γ (PPARγ) gene with litter size was studied in Large White and Landrace pig. Three SNP loci (P1, P2 and P7) on PPARγ₂ gene were determined by PCR–SSCP and the results showed that there were A → G mutations at 220 and 324 bp in 5′-regulator region and at 147 bp in exon 6, respectively. Allele frequencies were analysed in two breeds. Information on 2341 litter records from 564 sows was used to analyse the trait total number born (TNB) and number born alive (NBA). In Large White, TNB and NBA of genotype BB for P2 locus were the lowest, and the TNB and NBA of third and following parities and all parities were 0.74 and 0.51 piglets per litter less (P < 0.001) than those of the highest genotype AB, respectively, but for P1 and P7 locus the beneficial genotype AA were more 0.4–0.8 piglets per litter (P < 0.05) than the inferior genotype AB. In landrace, TNB and NBA of the first parity of genotype BB for P1 locus were 2.0 piglets per litter higher than AA (P < 0.05), but for all parities the TNB and NBA of genotype BB were 0.66 and 0.97 piglets per litter (P < 0.05) higher than AA, respectively. At P2 locus, the TNB and NBA of the second parity of genotype AA were obviously higher than those of AB (P < 0.05). And at P7 locus, the TNB and NBA of each parity of genotype AA were both about 2 piglets per litter more than those of BB (P < 0.05). The results indicated that PPARγ gene was significantly associated with litter size in pigs.     

Effect of VNTR polymorphism of the Muc1 gene on litter size of pigs

An investigation was undertaken to study the association between the variable number of tandem repeats polymorphism of the Muc1 gene and the litter size in pigs. Four different alleles were found in three breeds. The sequence analysis shows that the repetitive region of pig Muc1 gene is an array of 108-bp repeats. A total of 2,430 litter records from 897 sows genotyped at Muc1 gene were used to analyze the total number born (TNB) and number born alive (NBA). The study of the effects on litter size suggests that TNB and NBA of genotype AA are the highest in Large White, and the TNB and NBA of the third to ninth parities are 1.61 and 2.29 piglets per litter higher (P < 0.05) than those of the genotype DD, respectively. In Landrace, TNB and NBA of the genotype AA are 1.68 (P < 0.01) and 1.58 (P < 0.05) piglets per litter higher than those of the BB genotype in the third to ninth parities, but for all parities the TNB of genotype AA were 0.76 piglets per litter (P < 0.05) higher than BB. In Duroc, the TNB and NBA of genotype AA are about 1.5 piglets per litter more than those of DD in the third to ninth parities, though not significantly. The research suggests that the smaller allele tends to have higher litter size. The results indicate that Muc1 gene is significantly associated with litter size in pigs.     

猪PRLR和RBP4基因多态性与产仔性能的关系

采用PCR-RFLP方法, 对莱芜黑猪、鲁莱黑猪、里岔黑猪、鲁烟白猪、新沂蒙黑猪5个山东地方/培育猪种和大约克夏、长白、杜洛克3个引进猪种共8个猪种323头繁殖母猪进行PRLR和RBP4基因的多态性检测, 并采用最小二乘法分析其对产仔数影响的遗传效应。结果表明: 两个基因位点在8个猪种的测定群体中均存在多态性, 但山东地方/培育猪种与引进猪种间在基因型频率上存在较大差异。PRLR和RBP4基因对产仔数性状有显著影响(P<0.05), AA均为优良基因型。对于PRLR基因, 山东地方/培育猪种内AA基因型母猪的总产仔数和活产仔数比BB基因型母猪平均多产1.03头和0.89头, 引进猪种中AA基因型母猪比BB基因型母猪平均多产分别为1.26头和1.11头。对于RBP4基因, 山东地方/培育猪种内AA基因型母猪的总产仔数和活产仔数比BB基因型母猪平均多产0.59头和0.51头, 引进猪种中AA基因型母猪比BB基因型母猪平均多产分别为0.72头和0.64头     

5个与猪产仔数相关基因的效应分析

为了比较不同基因对猪产仔数效应大小,在相同的大白 （158头）、长白 （224头）猪群中采用PCR-RFLP法进行了ESR、FSHβ、PRL、PRLR、NCOA1 5种与产仔数相关基因的基因型频率检测及不同基因型的总产仔数和产活仔数效应分析,结果表明,对相同母猪群产仔数影响效应最大的是PRLR和NCOA1基因,AA型比BB型母猪总产仔数高2.28~3.33头（P<0.01）,产活仔数高1.57~3.30头（P<0.01）,其次为ESR和FSHβ基因,BB型比AA型母猪总产仔数高0.55~1.18头（P<0.05,长白例外）,产活仔数高0.37~1.20头（P<0.05）。PRL基因对产仔数效应不显著。     

Study on the Association Between Estrogen Receptor Gene (ESR) and Reproduction Traits in Landrace Pigs

To study the potential use of estrogen receptor gene (ESR) as a genetic marker to improve the reproductive traits of pigs, the genotypes of the ESR PCR product digested by Pvu II were determined in 2 239 litters from 612 Landrace sows. The data of the first, second, and later parities were separately evaluated. Although the frequency of the B allele was much lower than that of the A allele, likelihood ratio test showed that the gene frequencies were in Hardy-Weinberg equilibrium. The effects of ESR of different parities were not equal. In summary, the sows with the BB genotype showed better performance for total number of piglets born (TNB) and number of piglets born alive (NBA), but had a lower average piglet weight at birth (AWB). It was concluded that ESR could be used as a marker for the selection of litter size in the Landrace population.     

Litter size and piglet traits of gilts with different prolactin receptor genotypes

Seventy-seven Large White x Meishan F2 crossbred gilts with prolactin receptor (PRLR) genotype AA (n = 26), AB (n = 36) and BB (n = 15) were compared for teat number (FTm), age at first estrus, gestation length (GL), litter size, and litter means of functional teat number (FTp), birthweight (BW), and pre-weaning growth rate (GR). Own placental information was available for 88% of 620 live-born piglets (62 gilts), since placentae were labeled during farrowing. The effect of PRLR genotype of the mother on average placenta weight (PLW) and placenta efficiency (EFF = BW/PLW), was therefore, also analyzed, PRLR genotype significantly (P < 0.05) affected age at first estrus and, as a result (since the gilts were inseminated at a fixed estrus number), age and bodyweight at insemination. Furthermore, PRLR genotype affected total number of piglets born (TNB, P = 0.056) and number of piglets born alive (NBA, P = 0.072), but it did not affect (P > 0.3) GL, BW or GR, neither before nor after correction for litter size. BB gilts were significantly younger at first estrus and younger and lighter at insemination than AA gilts (P < 0.05). AA gilts had larger TNB (P = 0.047) and tended to have a larger NBA (P = 0.062) than BB gilts. TNB was 11.4 +/- 0.7, 10.8 +/- 0.6, and 8.8 +/- 0.9; NBA was 11.1 +/- 0.6, 10.5 +/- 0.6, and 8.7 +/- 0.9; BW was 1309 +/- 40, 1277 +/- 34, and 1290 +/- 53 g; and GL was 113.6 +/- 0.3, 113.8 +/- 0.3, and 113.5 +/- 0.4 days for AA, AB and BB gilts, respectively. The effects on litter size and age at first estrus are independent effects. PRLR affected PLW (P = 0.050) and EFF (P = 0.066), resulting in a difference between AA and BB gilts. PLW was 160 +/- 9, 181 +/- 7 and 196 +/- 11 g and EFF was 7.6 +/- 0.2, 7.3 +/- 0.2 and 6.7 +/- 0.3 for AA (n = 19), AB (n = 29) and BB (n = 14) gilts, respectively. After correction for TNB, the differences disappeared. Functional teat number of the AA. AB and BB gilts was 15.35 +/- 0.22, 15.53 +/- 0.18, and 15.60 +/- 0.29, respectively, and was not affected by PRLR genotype (P = 0.7). Functional teat number of piglets from AA, AB and BB mothers was 14.20 +/- 0.10, 14.37 +/- 0.08, and 14.63 +/- 0.13, respectively. Piglets from BB mothers had on average larger numbers of functional teats compared to piglets from AA mothers (P = 0.028). In conclusion, PRLR gene is a major gene or marker for age at first estrus, litter size, and litter average of number of functional teats in the Large White x Meishan F2 crossbred gilts studied. The favorable allele for litter size (A allele) is the unfavorable allele for age at first estrus and for litter mean of functional teat number.     

The effect of a SNP in ESR gene on the reproductive performance traits in Polish sows

The aim of the experiment was to detect polymorphism in the ESR gene to determine associations between the genotype and litter size in Polish Large White and Landrace sows. Reproductive traits investigated were: total number of piglets born (TNB), number of piglets born alive (NBA) and number of piglets weaned (TW). The polymorphism in ESR gene was detected using the PCR-RFLP method, with specific primers and the restriction enzyme AvaI. Two different alleles of ESR gene were identified: alleles A (0.71) and B (0.29). The relationship between the ESR genotypes and TBN, NBA and NW were analyzed. The analysis showed in first parity sows statistically significant (P < 0.01) differences between sows carrying different ESR genotypes. The analysis of ESR gene showed that sows with BB genotype had the largest litter size compared to AB and BB sows, but the difference was statistically not significant.     

大白猪BF基因多态性与繁殖性状及胎盘效率关联研究

文章以BF基因为产仔数的候选基因, 运用PCR-RFLP方法对大白猪BF基因内含子1序列进行分析, 发现内含子1第79 bp处发生了C→T突变, 命名为BF-intron 1-C79T。所扩增PCR产物经SmaⅠ酶切后, 可分出3种基因型, 分别为CC、CT和TT。经χ²适合性检验, 大白猪群体在该位点达到了Hardy-Weinberg平衡状态。将不同基因型与总产仔数(TNB)、产活仔数(NBA)、初生重(BW)和胎盘效率(PE)进行关联分析, 结果发现, 初产母猪在该位点上, CC基因型比CT基因型个体的TNB和NBA均多3.10头, 但差异不显著(P>0.05); 在BW和PE上, CC基因型均高于CT基因型, 差异不显著(P>0.05)。经产母猪在该位点上, CC基因型比TT基因型个体的TNB和NBA分别多3.45头和3.92头, PE高23.80%, 均达到显著水平; 但CT基因型个体与CC和TT个体之间的TNB 、NBA和PE差异不显著(P>0.05)。因此, BF-intron 1-C79T位点可作为繁殖性状及胎盘效率的潜在分子育种标记, 具有很大的研究价值。     

Effect of polymorphism in the leukemia inhibitory factor gene on litter size in Large White pigs

DNA polymorphism of the porcine leukemia inhibitory factory (LIF) was investigated and used to study the effects on litter size in Large White pigs. A total of 2,167 litter records from 420 sows genotyped at two SNP loci (LIF1 and LIF2) within LIF gene were analyzed to determine whether LIF influenced total number born (TNB) and number born alive (NBA). The results indicated that B allele at LIF1 locus and A allele at LIF2 locus seem to have advantageous effects on litter size. However, the combined analyzed results demonstrated that genotype AAAA, ABBB, and BBBB are better than genotype AAAB, AABB, and ABAB for TNB and NBA in either third to eighth parity or all parities. In all parities, the sows with AAAA genotype had an advantage of 1.76 piglets (P < 0.001) for TNB and 1.44 piglets (P < 0.01) for NBA per litter over the AAAB sows, respectively. The results in this study demonstrated that LIF gene was significantly associated with litter size in pigs. H. C. Lin and G. F. Liu contributed equally to this work.     

MyoG基因对金华猪繁殖性状的影响

用PCR-RFLP方法对金华猪I系（109头）、II系（15头）、III系（25头）的MyoG基因的第二内含子内（PCR1- MspⅠ-RFLP）和3'-端（PCR2- MspⅠ-RFLP）位点进行了多态性分析。结果表明：PCR1- MspⅠ-RFLP位点有3种基因型（AA、AB、BB）,其基因型频率分别为0.1544,0.3826,0.4631;PCR2- MspⅠ-RFLP位点只有2种基因型（MM、MN）,其基因型频率分别为0.9953和0.0047。采用SPSS程序分析MyoG基因对金华猪繁殖性状的影响。结果表明：MyoG基因对金华母猪初胎的总产仔数、二胎的产活仔数影响显著（P<0.05）,而对其他胎次组合的总产仔数、产活仔数以及初生窝重没有显著影响（P<0.05）。     

Associations between PRLR/AluI gene polymorphism with reproductive,growth, and meat traits in pigs

The aim of this study was to determine the associations between genotypes of the prolactin receptor gene (PRLR) and reproductive, growth, and meat traits in pigs. Genetic groups of sows were used: Large White (LW), Danish Landrace (LD), and Landrace × Yorkshire × Duroc hybrids (L × Y × D). Reproductive traits studied were the total number of born (TNB) and the number born alive (NBA). The growth traits were the number of days to 100 kg and the average daily gains (ADG). The meat traits were the average backfat thickness (BFT), half carcass weight (HCW), area of M. longissimus dorsi (MLT), and lean meat content (LM). The polymorphism was detected using the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) method. It was found that the genotype BB is associated with the best NBA. In sows LD, the AB genotype is associated with best number of days to 100 kg; in hybrids L × Y × D, the AA genotype is associated with better meat traits as compared to the genotype BB.     

雌激素受体基因和长白猪繁殖性能相关研究

通过检测612头长白母猪共2 239窝ESR基因的PvuⅡ酶切多态性,分析了不同ESR基因型和长白母猪繁殖性状的相关,以确定ESR基因在猪育种应用的可能性.头胎母猪、第2胎母猪和3胎以上母猪的资料分开统计.群体中B等位基因的频率很低,但似然比检验结果显示群体的基因频率处于哈代-温伯格连锁平衡状态.第1胎BB基因型母猪的总产仔数显著高于AA型母猪(12.05±0.82 vs 10.19±0.24)(P＜0.05),但BB基因型母猪的初生仔猪重显著低于AA型母猪(1.23±0.07vs 1.42±0.02)(P＜0.05).第3胎以上资料合并,BB基因型母猪的总产仔数显著多于AA和AB基因型母猪(11.98±0.63 vs10.90±0.48/10.92±0.51)(P＜0.05),产活仔数显著高于AA型母猪(10.31±0.58 vs 9.43±0.45)(P＜0.05);AB基因型母猪初生仔猪重显著低于AA型母猪(1.44±0.04 vs 1.48±0.04)(P＜0.05).所有资料合并,BB基因型母猪的总产仔数极显著高于AB型母猪(11.63±0.52 VS 10.63±0.42)(P＜0.01),显著高于AA型母猪(11.63±0.52 vs 10.70±0.40)(P＜0.05);BB基因型母猪的产活仔数显著高于AB和AA基因型母猪(10.15±0.50 vs 9.33±0.39/9.41±0.41)(P＜0.05).其余情况下各基因型母猪间繁殖性状间差异不显著(P＞0.05).总之,BB基因型母猪的总产仔数和产活仔数优于其他基因型母猪,但仔猪初生重较低.ESR基因可以作为遗传标记,用于本群长白猪产仔数的选择.     

The effect of estrogen receptor genotype on litter size and placental traits at term in F2 crossbred gilts

The effect of estrogen receptor (ESR) genotype (two alleles, A and B) on litter size of 275 Large White x Meishan F2 crossbred gilts (73 AA, 126 AB and 76 BB gilts) was tested. In addition, for 63 of these gilts (18 AA, 24 AB, and 21 BB) the effect of ESR genotype on average placental traits at term was tested, since individual placental information was available for 88% of the 628 liveborn piglets. Without affecting average birth weight of the piglets, ESR genotype significantly affected litter size, i.e. AB gilts had larger litters than BB gilts (P < 0.05). Total number born was 11.38+/-0.38, 11.88+/-0.28, and 10.68+/-0.35, while number born alive was 10.45+/-0.39, 11.07+/-0.29, and 9.85+/-0.36 for AA, AB and BB gilts, respectively. Since the B allele in previous research was associated with largest litters, the hypothesis that ESR is a marker rather than the major gene itself is discussed. Average placental length, surface area, and weight including and excluding amnion were not affected by ESR genotype. However, placentae of AB gilts had a significantly lower number of areolae per placenta than BB gilts and had a lower number of areolae/cm2 placenta than AA and BB gilts. Number of areolae was 8945+/-663, 7240+/-619, and 9694+/-633, for AA, AB and BB gilts, respectively. Although the reason for the low number of areolae on placentae in AB gilts is not yet known, the results suggest that the ESR linked major gene for litter size might be involved in the development and activity of endometrial glands.     

Pig melatonin receptor 1a (MTNR1A) genotype is associated with seasonal variation of sow litter size

The duration of nocturnal melatonin secretion reaches its minimum in summer, a physiological event that is likely related with the diminished sow fertility and delayed puberty typically observed in this season. Melatonin exerts its function by binding two different receptors named as MTNR1A and MTNR1B. Interestingly, the MTNR1A gene is located on a chromosome SSC17 region where QTL for prolificacy traits have been detected in previous studies. In this work, we have found a synonymous T162C polymorphism at exon 2 of the pig MTNR1A gene. An association analysis between this polymorphism and sow prolificacy in an Iberian ×  Meishan intercross was performed. The utilization of four statistical models of increasing complexity demonstrated that the MTNR1A gene has both additive and dominant effects on total number of born piglets (TNB) and number of piglets born alive (NBA). Additive effects were significant in summer (TNB, P < 0.01; NBA, P < 0.001), whereas dominant effects reached significance both in fall (TNB, P < 0.01; NBA, P < 0.05) and in winter (TNB, P < 0.001; NBA, P < 0.05). The seasonal variation observed for MTNR1A additive and dominant effects might be produced by the influence of photoperiod on the pattern and duration of melatonin secretion. These results illustrate that the complex interaction between genotype and environment can be an important source of phenotypic variation of reproductive traits.     

Polymorphism of the estrogen receptor 1 locus in populations of pigs of different genotypes and its association with reproductive traits of large white sows

Populations of Large White, Large Black, Poltava Meaty, Pietrian, and Meishan pigs are characterized by intron PvuII polymorphism in the estrogen receptor 1 gene (ESR1). These breeds differ in ESR1 alleles and genotypes frequencies. In the populations, there are deviations in the genotype distribution from the Hardy-Weinberg equilibrium. The established estrogen receptor 1 locus association with the reproductive traits of Large White sows indicates the possibility of using intron ESR1 PvuII polymorphism as a genetic pregnancies marker in pig selection.     

Association of EphA4 polymorphism with swine reproductive traits and mRNA expression of EphA4 during embryo implantation

The swine erythropoietin-producing hepatocellular A4 (EphA4) gene, which was detected in the endometrium during embryo implantation in pigs, was one of the potential candidate genes for reproductive traits. In the study, two single nucleotide polymorphism (SNP) loci (EphA4_1 and EphA4_2) in exon 3 of EphA4 gene were analyzed to determine whether EphA4 influenced total number born (TNB) and number born alive (NBA). Association of two diallelic polymorphisms with reproductive traits was assessed in Landrace, Yorkshire and Duroc populations with 2,014 litter records of 765 sows. The results showed that G allele at EphA4_1 locus or C allele at EphA4_2 locus seemed to have advantageous effects on litter size. And the combined analyzed results demonstrated that genotype AGTC, AGCC and GGCC are better than genotype AATT, AATC and AGTT for TNB and NBA in either single parity or all parities. The results in this study demonstrated that EphA4 gene was significantly associated with litter size in pigs. In addition, a high mRNA expression of EphA4 was found in small intestine, large intestine, stomach and endometrium, and the expression decreased during implantation in pigs. Further studies were needed to confirm these preliminary researches.     

Effects of fixed-time artificial insemination using triptorelin on the reproductive performance of pigs: a meta-analysis

Triptorelin (TRI), a gonadotropin-releasing hormone agonist allowing ovulation synchronization in pigs, is indispensable for fixed-time artificial insemination (FTAI) protocols. However, the effect of FTAI using TRI (FTAI-TRI) on the reproductive performance is controversial. We performed a meta-analysis to determine whether FTAI-TRI affects reproductive performance of pigs, including pregnancy rate (PR), number of pigs born alive per litter (NBA), farrowing rate (FR) and total number of pigs born per litter (TNB). A total of 37 trials from 15 studies were extracted and analysed in Stata. A weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for NBA and TNB, and risk ratio (RR) with 95% CI was calculated for PR and FR. Pregnancy rate, TNB and NBA data were applied to a fixed-effect protocol, and FR data were applied to a random-effect protocol. We found that for weaned sows, the FTAI-TRI group had comparable reproductive performance to the artificial insemination (AI) following oestrus detection (EDAI) group. Fixed-time AI has many advantages, including the elimination of the need to heat-check twice daily, so that FTAI-TRI is a good substitute for EDAI. Subgroup analysis indicated that the optimal timing of triptorelin treatment was 96 h after weaning, which gave significant positive effects on PR (RR = 1.08, P = 0.000) and non-significant positive effects on TNB (WMD = 0.12, P = 0.452). Triptorelin at a dose of 100 μg showed better effects than 200 μg, with significant positive effects on PR (RR = 1.09, P = 0.005) and FR (RR = 1.06, P = 0.036). So a single dose of 100 μg was recommended. The optimal protocol was insemination at 24 h and again at 48 h after triptorelin administration if they remained in standing oestrus, and this provided a significantly higher NBA (WMD = 0.59, P = 0.013) that increased by 0.59. For gilts, the FTAI-TRI group showed decreased (not significant) PR (RR = 0.96, P = 0.127) and significantly decreased FR (RR = 0.93, P = 0.013), TNB (WMD = −0.85, P = 0.006) and NBA (WMD = −0.98, P = 0.000), which were inferior to those in the EDAI group. In conclusion, the effects of FTAI-TRI on the reproductive performance of pigs were parity-, treatment timing-, insemination timing-, and dosage-dependent. Fixed-time AI using triptorelin could effectively replace the EDAI protocol for sows, but not for gilts.     

Meta-analysis of Genetic Structure and Association of Prolactin Gene with Performance Traits in Dairy Cattle in India

The present meta-analysis was carried to provide the more reliable estimates of gene frequency and association of Rsa 1 generated candidate genotype of prolactin gene within exon-3 with performance traits in 1198 Indian dairy cows using data from 15 published studies. Six genetic models viz., codominant (AA vs. AB, AA vs. BB and AB vs. BB), dominant (AA+AB vs. BB), completely over dominant (AA+BB vs. AB) and recessive (AA vs. AB+BB) were used to obtain standardized mean difference (SMD) between genotypes. Meta-analysis showed that the gene frequency of A allele (156 bp) was 0.60 (95% confidence interval (CI) 0.54, 0.65). In association analysis, cows with AB genotype [SMD?=?0.65, 95% CI 0.00, 1.30] had significantly (P?<?0.05) higher lactation milk yield (LMY) as compared to BB genotype, whereas AA and AB genotypes had similar trend. Likewise, AA?+?AB also had larger effect [SMD?=?2.31, 95% CI 0.21, 4.10] on LMY as compared to BB. Cows with AB genotype had significantly lower age at first calving (AFC) with small effect [SMD (AA vs. AB)?=?1.38, 95% CI 0.06, 2.70] and medium effect [SMD (AB vs. BB)?=????3.83, 95% CI???6.41,???1.24] as compared to cows with AA and BB genotypes, respectively. This finding was confirmed under dominant and completely over dominant models. In case of fat%, AA genotype showed negative effect (SMD?=????0.51, 95% CI???0.84,???0.17) under recessive model. It was concluded that the propagation of allele A is promising to help dairy farmers to improve the genetic quality of their dairy cows.