Three novel single-nucleotide polymorphisms of complement component 4 gene (C4A) in Chinese Holstein cattle and their associations with milk performance traits and CH50

Complement component 4 (C4A) is a candidate gene that reflects complement activity. The primary role of this gene in the classical and lectin-activation pathways is to provide protection against bacterial pathogens. In the current study, the bovine complement C4A gene was screened for polymorphisms, and the associations of these polymorphisms with the hemolytic activity of the classical pathway (CH50), C4 serum levels, and milk performance traits were examined. Three novel single-nucleotide polymorphisms (rs 132741478: g.2994 A>G, rs 134006517: g.3508 A>G, and rs 137485678: g.3649 G>C) were detected by DNA sequencing and PCR-RFLP in 1182 Chinese Holstein cows. The rs 132741478: g.2994 A>G mutation in exon 10 led to methionine and valine exchange at position 362, whereas rs 134006517: g.3508 A>G and rs 137485678: g.3649 G>C were synonymous substitutions. The statistical analyses revealed that cows with rs 132741478: g.2994 A>G-AG and rs 137485678: g.3649 G>C-CC have significantly lower somatic cell scores (SCS, P<0.01). Homozygote cows with GAC haplotypes have the lowest SCS, whereas AAG/AAC cows have the highest. The serum concentration of C4 by ELISA and the hemolytic and antibacterial activity of CH50 were also evaluated in the current study. The results confirmed that rs 132741478: g.2994 A>G in the coding sequence of the β-chain of the bovine C4A gene is related to mastitis resistance. This polymorphism may be very important in marker-assisted selections in dairy cattle breeding programs.     

GH基因遗传多态性与中国荷斯坦牛泌乳性状的遗传效应分析

为分析GH基因SNPs与中国荷斯坦牛泌乳性状的相关性。以Z32头中国荷斯坦牛为研究材料,采用PCRSSCP技术检测GH基因第5外显子及其相邻区域的多态性,并进行相关性分析。结果发现GH基因第4内舍子（2017bp处）存在C—T的碱基转换,该群体在此位点处于Hardy-Weinberg平衡状态,为中度多态。与泌乳性状的相关性分析表明,该多态位点与泌乳性状显著相关（P〈0．05）,TT型305d产奶量、305d乳脂量、305d乳蛋白量和305d乳糖量显著高于CC型（P〈0．05）;TC型与TT型、CC型之间305d产奶量、305d乳脂量、305d乳蛋白量差异均不显著（P〉0．05）,但TC型在数值上有优于CC型的趋势。建议将等位基因T作为提高奶牛产奶量、乳脂量和乳蛋白量的候选分子标记。     

PPP1CB基因多态性与西门塔尔牛肉质性状相关性分析

选用134头西门塔尔牛为试验材料,采用PCR-RFLP的方法对PPP1CB基因的第一内含子进行检测,利用SPSS软件对该基因内含子1的多态性与肉质性状进行相关性分析。分析结果表明:PPP1CB基因的第一内含子第14 434bp碱基处存在C/T基因突变,该基因多态性与屠宰率呈显著相关,对其他性状的影响差异不显著。本文首次揭示了PPP1CB基因与牛肉质性状的相关性,为西门塔尔牛利用该基因的多态性进行分子育种提供了试验依据。     

Polymorphism in GHRH gene and its association with growth traits in Chinese native cattle

Growth hormone-releasing hormone (GHRH) is secreted by the hypothalamus and stimulates growth hormone (GH) released from the pituitary. Mutations detected in GHRH gene showed associations with animal production traits. The purpose of this study was to investigate the association of the GHRH gene with growth traits in Chinese native cattle. PCR-SSCP and sequencing were used to detect mutations of the GHRH gene in this study. One novel mutation 4251nt (C>T) was found and the frequencies of C allele were 0.8778 and 0.8476 for Qinchuan and Nanyang cattle, respectively. Body weight with the CT genotype was significantly higher (P<0.05 or P<0.01) than those with CC genotype for different growth periods (6, 12, 18, and 24 months old) in Nanyang cattle. Our findings suggested that polymorphism in bovine GHRH might be one of the important genetic factors to influence body weight.     

草原红牛二酞甘油酞基转移酶2（DGAT2）基因的多态性及与泌乳性状关联性分析

为研究草原红牛二酞甘油酞基转移酶2（DGAT2）的多态性及与泌乳性状相关性,采用PCR-RFLP方法检测DGAT2基因的遗传多态性。结果检测到AA、AB和BB 3种基因型,统计分析表明该多态位点与草原红牛乳中脂肪和干物质含量呈显著相关,脂肪：AA型极显著高于AB型和BB型（P〈0.01）,AB型和BB型之间差异不显著（P〉0.05）;干物质：AA型显著高于AB型（P〈0.05）,极显著高于BB型（P〈0.01）,而AB型又显著高于BB型（P〈0.05）;其他泌乳性状的基因型间差异不显著（P〉0.05）。此结果提示,DGAT2基因对草原红牛乳中脂肪和干物质含量具有较大的遗传效应,可以初步推断DGAT2是控制这些性状的众多基因之一,可能是影响草原红牛乳中脂肪和干物质含量的一个主效基因或与主效基因相连锁,可作为选育草原红牛低脂及高干物质奶牛的分子标记,用于标记辅助选择意义重大。     

Genetic associations between temperament and performance traits in Nellore beef cattle

The aim of this study was to estimate genetic associations between temperament and performance traits. Temperament was evaluated in yearling male and female Nellore cattle, using four traits: temperament score (TS), for assessing animals’ reactions in a corral pen (n = 25 691); movement score (MOV), for animals’ movements recorded inside the crush; crush score (CS), for animal's general reactivity inside the crush; and flight speed (FS), for the speed (in m/s) at which the animals exited the crush (n = 11 697, for the last three methods); for all the temperament traits, lower scores indicate animals with calmer temperament. Performance traits were visual scores for conformation (C), finishing precocity (P) and muscling (M) evaluated at yearlings, and average daily gain (ADG) was estimated from weaning to yearling. Bayesian inference using Gibbs sampling was applied to estimate (co)variance components and genetic and phenotypic parameters. Heritability estimates for the temperament traits ranged from 0.07 (CS) to 0.28 (FS). Genetic correlations of the temperament traits with ADG and C, P and M were negative and ranged from −0.02 to −0.31. Phenotypic correlations were negative and consistently lower than the genetic, ranging from −0.08 to −0.02. It was concluded that the temperament traits assessed had favourable genetic correlation estimates with the performance traits studied. However, indirect responses in temperament when selecting for higher ADG and visual scoring system of C, P and M, will be low.     

Effect of DGAT1 and TG gene polymorphisms on intramuscular fat and on milk production traits in different cattle breeds in Hungary

The objective of this study was to estimate the effect of the thyroglobulin (TG) locus on beef quality traits in some beef cattle breeds and to investigate the effect of the DGAT1 locus on milk production traits in the Hungarian Holstein Friesian population. TG and DGAT1 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. At the TG locus TT bulls showed the highest fat percentage values in the longissimus dorsi muscle (m. longissimus dorsi); the difference between CC and TT genotypes was significant. DGAT1 GC/GC cows had the highest milk, fat and protein yield values. Due to the relatively small number of GC/GC cows the difference proved to be significant only between AA/AA and AA/GC genotypes.     

Evaluation of single-nucleotide polymorphisms in CAPN1 for association with meat tenderness in cattle

Micromolar calcium activated neutral protease (CAPN1) was evaluated as a candidate gene for a quantitative trait locus (QTL) on BTA29 affecting meat tenderness by characterization of nucleotide sequence variation in the gene. Single-nucleotide polymorphisms (SNP) were identified by sequencing all 22 exons and 19 of the 21 introns in two sires (Piedmontese x Angus located at the U.S. Meat Animal Research Center in Clay Center, NE; Jersey x Limousin located at AgResearch in New Zealand) of independent resource populations previously shown to be segregating meat tenderness QTL on BTA29. The majority of the 38 SNP were found in introns or were synonymous substitutions in the coding regions, with two exceptions. Exons 14 and 9 contained SNP that were predicted to alter the protein sequence by the substitution of isoleucine for valine in Domain III of the protein, and alanine for glycine in Domain II of the protein. The resource populations were genotyped for these two SNP in addition to six intronic polymorphisms and two silent substitutions. Analysis of genotypes and shear force values in both populations revealed a difference between paternal CAPN1 alleles in which the allele encoding isoleucine at position 530 and glycine at position 316 associated with decreased meat tenderness (increased shear force values) relative to the allele encoding valine at position 530 and alanine at position 316 (P < 0.05). The association of maternal alleles with meat tenderness phenotypes is consistent with the hypothesis of CAPN1 as the gene underlying the QTL effect in two independent resource populations and presents the possibility of using these markers for selective breeding to reduce the numbers of animals with unfavorable meat tenderness traits.     

Associations of polymorphisms in the Pit-1 gene with growth and carcass traits in Angus beef cattle

The Pit-1 gene was studied as a candidate for genetic markers of growth and carcass traits. Angus beef cattle that were divergently selected for high- or low-blood serum IGF-I concentration were used in this study. The single-strand conformation polymorphism method was used to identify polymorphism in the Pit-1 gene including regions from intron 2 to exon 6. Two polymorphisms, Pit1I3H (HinfI) and Pit1I3NL (NlaIII), were detected in intron 3 of the Pit-1 gene. One polymorphism, Pit1I4N (BstNI), was found in intron 4, and a single nucleotide polymorphism, Pit1I5, was found in intron 5. The previously reported polymorphism in exon 6, Pit1E6H (HinfI), was also studied in 416 Angus beef cattle. Associations of the polymorphisms with growth traits, carcass traits, and IGF-I concentration were analyzed using a general linear model procedure. No significant associations were observed between these polymorphisms and growth and carcass traits.     

Statistical associations between restriction fragment length polymorphisms and quantitative traits in beef cattle.

Data on 41 traits from 677 animals produced in a five-breed diallel were matched with genotypes for five marker-loci provided by restriction fragment length polymorphisms to detect quantitative effects associated with the markers, following three different designs based on inbred lines, half-sib families, and on assumptions of the markers being quantitative trait loci (QTL). Three growth hormone-TaqI alleles, B, C, and D, in high frequencies in this sample of the Brahman breed, were associated with decreases in birth weight, as a maternal trait (P < .01), and decreases in shoulder width at birth (P < .05). Among F2 Angus-Brahman and Brahman-Hereford cows, homozygotes for the B, C, or D alleles gave birth to calves 4.0 kg lighter than cows homozygous for the A allele, an effect that amounts to the magnitude of the corresponding breed difference in the diallel, and represents one phenotypic SD. A putative cytoplasmic effect seems to interact (P = .02) with this effect on maternal birth weight. Also, at birth, F2 calves homozygous for the B, C, or D alleles were .8 cm narrower at the shoulders than those homozygous for the A allele, after adjusting for birth weight. Significant associations (P < .05) between the parathyroid hormone-MspI marker and measures of body size were detected, as well as an effect on weaning weight (P = .03) as a maternal trait, whose magnitude (17.5 kg) equals the Brahman vs Angus and Hereford breed difference, as quantified in the diallel, and represents .8 of a phenotypic SD. No significant associations were found for three other marker-loci (prolactin-MspI, osteonectin-EcoRI, and keratin VI-MspI). Restriction fragment length polymorphisms have the potential to provide new insights and useful applications to animal breeding, but, as in this work, small sample sizes, extreme susceptibility to Type I errors, and different types of possible confounding obfuscate the conclusions that can be drawn from studies of limited scope and less than ideal planning.     

Genetic structure of milk protein polymorphisms and effects on milk production traits in a local dairy cattle

The milk protein genetic structure of the Reggiana dairy local cattle with remarkable milk quality properties was analysed and compared with the structure of Italian Friesian and Italian Brown cattle. A total of 1138 individual milk samples from the three breeds were typed by isoelectrofocusing. Polymorphism was found at the α_s1‐casein (CSN1S1), β‐casein (CSN2), κ‐casein (CSN3), and β‐lactoglobulin (LGB) loci. High frequencies were observed for some casein alleles in Reggiana (CSN1S1*C, 25%; CSN2*B: 28%) with considerable differences to those observed in a survey carried out 30 years before. A great variation among breeds was observed for casein haplotype frequencies and high linkage disequilibrium was detected at the three polymorphic casein loci CSN1S1‐CSN2‐CSN3. The prevalent haplotypes were CA²B (23%; Reggiana), BA²A (48%; Italian Friesian) and BA²B (51%; Italian Brown). Higher G_ST values between breeds were observed when haplotype frequencies were considered instead of gene frequencies. In the Reggiana cattle, the occurrence of two casein alleles at a rather high frequency (CSN1S1*C, CSN2*B) allowed to estimate the effects of rare casein haplotypes on milk traits. The CA²B haplotype was associated with a significantly higher milk protein and fat content and a significantly higher protein per cent was found also for the BA¹B haplotype.     

奶牛催乳素基因多态性及其与产奶性状的关联分析

催乳素(PRL)基因是影响奶牛泌乳性状的重要候选基因。通过PCR-RFLP结合测序方法检测了荷斯坦奶牛PRL基因5'侧翼区调控序列的多态性,并利用最小二乘法分析其与泌乳性状的关联性。结果显示:在PRL基因5'侧翼序列的906位点处发现A/G突变。共发现AA、AG和GG三种基因型,基因型频率分别为0.239 3、0.522 8和0.177 9,A和G的等位基因频率为0.530 7和0.469 3。多态信息含量检测结果显示该位点处于中度多态,卡方检验显示该位点处于Hardy-Weinberg不平衡状态(P0.05)。关联分析结果表明,该位点多态对产奶量、乳脂率均有影响。     

Identification of single nucleotide polymorphisms in the bovine Toll-like receptor 1 gene and association with health traits in cattle

ABSTRACT: Bovine mastitis remains the most common and costly disease of dairy cattle worldwide. A complementary control measure to herd hygiene and vaccine development would be to selectively breed cattle with greater resistance to mammary infection. Toll-like receptor 1 (TLR1) has an integral role for the initiation and regulation of the immune response to microbial pathogens, and has been linked to numerous inflammatory diseases. The objective of this study was to investigate whether single nucleotide polymorphisms (SNPs) within the bovine TLR1 gene (boTLR1) are associated with clinical mastitis (CM).Selected boTLR1 SNPs were analysed within a Holstein Friesian herd. Significant associations were found for the tagging SNP -79 T > G and the 3'UTR SNP +2463 C > T. We observed favourable linkage of reduced CM with increased milk fat and protein, indicating selection for these markers would not be detrimental to milk quality. Furthermore, we present evidence that some of these boTLR1 SNPs underpin functional variation in bovine TLR1. Animals with the GG genotype (from the tag SNP -79 T > G) had significantly lower boTLR1 expression in milk somatic cells when compared with TT or TG animals. In addition, stimulation of leucocytes from GG animals with the TLR1-ligand Pam3csk4 resulted in significantly lower levels of CXCL8 mRNA and protein.SNPs in boTLR1 were significantly associated with CM. In addition we have identified a bovine population with impaired boTLR1 expression and function. This may have additional implications for animal health and warrants further investigation to determine the suitability of identified SNPs as markers for disease susceptibility.     

澳系进口荷斯坦奶牛CXCR1基因遗传多态性与泌乳性状及体细胞评分的关联性分析

采用聚合酶链式反应-单链构象多态性（PCR—SSCP）技术对以海丰奶牛场588头澳系进口荷斯坦牛牛趋化因子受体1（Chemokine receptor1,CXCR1）基因的遗传多态性进行分析;采用混合动物模型分析CXCRl基因2个突变位点与测定日产奶量、乳脂率、乳蛋白率、305d产奶量、305d乳脂量、305d乳蛋白量及体细胞评分7个性状的相关性,寻找可用于生产实际的分子标记。结果显示,CXCR1基因5’侧翼区-1830位点发生了A—G的突变,检测到AA、AG和GG3种基因型,频率分别为0．684、0．289和0．027,等位基因A和G的频率分别为0．828和0．172;GG基因型奶牛的日产奶量、SCS和305d产奶量均板显著高于AA基因型（P〈0．01）,而其乳脂率和乳蛋白率却显著低于AA基因型奶牛（P〈0．05）。编码区783位点仅发现AA和AC2种基因型,基因型频率分别为0．886和0．114,等住基因A和c的频率分别为0．943和0．057。AA型的个体的日产奶量、305d脂肪产量和305d蛋白产量极显著高于AC型个体,而其乳脂率、乳蛋白率和SCS却极显著低于AC型个体（P〈O．01）。结果表明,CXCR1基因遗传突变对澳系进口荷斯坦牛泌乳性状和乳房炎抗性有较大的遗传效应,可用于澳系进口荷斯坦牛的分子标记辅助选择。     

澳系进口荷斯坦奶牛CXCR1基因遗传多态性与泌乳性状及体细胞评分的关联性分析

采用聚合酶链式反应-单链构象多态性(PCR-SSCP)技术对以海丰奶牛场588头澳系进口荷斯坦牛牛趋化因子受体1(Chemokine receptor 1,CXCR1)基因的遗传多态性进行分析;采用混合动物模型分析CXCR1基因2个突变位点与测定日产奶量、乳脂率、乳蛋白率、305d产奶量、305d乳脂量、305d乳蛋白量及体细胞评分7个性状的相关性,寻找可用于生产实际的分子标记。结果显示,CXCR1基因5′侧翼区-1830位点发生了A→G的突变,检测到AA、AG和GG 3种基因型,频率分别为0.684、0.289和0.027,等位基因A和G的频率分别为0.828和0.172;GG基因型奶牛的日产奶量、SCS和305d产奶量均极显著高于AA基因型(P<0.01),而其乳脂率和乳蛋白率却显著低于AA基因型奶牛(P<0.05)。编码区783位点仅发现AA和AC 2种基因型,基因型频率分别为0.886和0.114,等位基因A和C的频率分别为0.943和0.057。AA型的个体的日产奶量、305d脂肪产量和305d蛋白产量极显著高于AC型个体,而其乳脂率、乳蛋白率和SCS却极显著低于AC型个体(P<0.01)。结果表明,CXCR1基因遗传突变对澳系进口荷斯坦牛泌乳性状和乳房炎抗性有较大的遗传效应,可用于澳系进口荷斯坦牛的分子标记辅助选择。     

牛POU1F1-exon6多态性与生长性状的相关性研究

为了研究弗莱维赫牛和蒙贝利亚牛POU1F1-exon6多态性与体重、体尺等生长性状指标的相关性,试验采用PCR-RFLP技术分析其多态性,并采用最小二乘法拟合线性模型,对各标记基因型与部分生长性状指标差异显著性进行检验。结果表明:2个群体POU1F1-exon6基因存在2个等位基因A/G,基因频率分别为0.175 9/0.824 1,0.096 8/0.903 2;在该位点上,弗莱维赫牛处于Hardy-weinberg平衡状态(P0.05),而蒙贝利亚牛处于不平衡状态(P0.05);2个群体中AA基因型体重均值高于AG、GG基因型均值(P0.05),GG和AG基因型个体腹围均值高于AA基因型个体均值(P0.05),但在体高、体长、胸围和管围4个性状上无显著性差异(P0.05)。说明POU1F1基因的A15636G位点可以作为牛的体重和腹围指标的候选遗传标记之一。     

Association between single nucleotide polymorphisms (SNPs) and milk production traits in Italian Brown cattle

Italian Brown is a cattle breed largely exploited in the production of many dairy products in Italy, including typical and traditional cheeses. For this reason, the improvement of selection methods is of economic relevance while a deeper understanding of the genetic mechanisms regulating milk production is of general scientific interest. We selected a total of 561 samples, representing virtually all Italian Brown bull population, to test for association between milk production traits and 29 known genes harbouring 106 single nucleotide polymorphisms (SNPs). After filtering, a total of 31 SNPs in 22 candidate genes and 473 bulls were retained. Associations between each SNP and milk traits were tested by a mixed model approach, obtaining seven significantly associated SNPs, two of which (in β-Lactoglobulin) associated with all traits, and four (in Chemokin receptor I, αs1 casein, k casein, fatty acid synthase, thyroid hormone responsive and Oxytocin prepropetide genes) associated with at least one trait.