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Genetic basis of mastitis resistance in dairy cattle – a review

January 2013
Annals of Animal Science 13(4):663

DOI:10.2478/aoas-2013-0043,

Authors:

South Valley University

Mastitis is one of the most important mammary gland diseases impacting lactating animals. Resistance to this disease could be improved by breeding. There are several selection methods for mastitis resistance. To improve the natural genetic resistance of cows in succeeding generations, current breeding programmes use somatic cell count and clinical mastitis cases as resistance traits. However, these methods of selection have met with limited success. This is partly due to the complex nature of the disease. The limited progress in improving udder health by conventional selection procedures requires applying information on molecular markers of mastitis susceptibility in marker-assisted selection schemes. Mastitis is under polygenic control, so there are many genes that control this trait in many loci. This review briefly describes genome-wide association studies which have been carried out to identify quantitative trait loci associated with mastitis resistance in dairy cattle worldwide. It also characterizes the candidate gene approach focus on identifying genes that are strong candidates for the mastitis resistance trait. In the conclusion of the paper we focus our attention on future research which should be conducted in the field of the resistance to mastitis. Key words: dairy cattle, mastitis, genetic markers

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Geneticbasisofmastitis

resistanceindairycattle–a

review

ARTICLEinANNALSOFANIMALSCIENCE·JANUARY2013

ImpactFactor:0.42·DOI:10.2478/aoas-2013-0043,

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1AUTHOR:

KarimaGalalAbdelhameed

SouthValleyUniversity

18PUBLICATIONS19CITATIONS

SEEPROFILE

Availablefrom:KarimaGalalAbdelhameed

Retrievedon:30July2015

Ann. Anim. Sci., Vol. 13, No. 4 (2013) 663– 673, DOI: 10.2478/aoas-2013-0043

GENETIC BASIS OF MASTITIS RESISTANCE IN DAIRY CATTLE –

A REVIEW* *

1

 

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1



2



Abstract

Mastitis is one of the most important mammary gland diseases impacting lactating animals. Re-

sistance to this disease could be improved by breeding. There are several selection methods for

mastitis resistance. To improve the natural genetic resistance of cows in succeeding generations,

current breeding programmes use somatic cell count and clinical mastitis cases as resistance traits.

However, these methods of selection have met with limited success. This is partly due to the com-

plex nature of the disease. The limited progress in improving udder health by conventional selec-

tion procedures requires applying information on molecular markers of mastitis susceptibility in

marker-assisted selection schemes. Mastitis is under polygenic control, so there are many genes

that control this trait in many loci. This review briey describes genome-wide association studies

which have been carried out to identify quantitative trait loci associated with mastitis resistance

in dairy cattle worldwide. It also characterizes the candidate gene approach focus on identifying

genes that are strong candidates for the mastitis resistance trait. In the conclusion of the paper we

focus our attention on future research which should be conducted in the eld of the resistance to

mastitis.

Key words: dairy cattle, mastitis, genetic markers

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



 



           













 

      



    









Current breeding programme





     

          

    







Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

Mastitis resistance in dairy cattle 











        



 



       

           























  

       









Molecular markers of mastitis resistance

         





       







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

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

Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

G. Sender et al.

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

     

           













Detection and localization of QTLs







          

















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Bos taurus

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            

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       

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      

          

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  

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    

      

Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

Mastitis resistance in dairy cattle 



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    

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          

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









       

   



      





          









    









          







Candidate gene approach

        













    



Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

G. Sender et al.

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

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        

           











 E. coli      

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



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

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         



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



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





 

  

BoLA-DRB3

        

BoLA-DRB3        

            

      

BoLA-DRB3.2*24         

BoLA-DRB3.2*3         

 



16 

23   S. dysga-

lactiae       23     

Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

Mastitis resistance in dairy cattle 









  









    







 







S. aureus

           

      

ATP1A1++





           



Conclusion





   



 

           















      



    





Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

G. Sender et al.

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References

 

                 









           









 

                          





     





DRB3.2*16DRB3.2*23



                                    





                                      



       





             





   



                           





                   



                         



                         





       



                                 



                           







                   



Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

Mastitis resistance in dairy cattle 

            





            



                             





   



                              





            ATP1A1



         



      







 











      





                



                            





                             





                               







                        



                                   





                                   

     



                





                                      



Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

G. Sender et al.





                                  





            









                      









                        





BoLA-DRB3



    

                          



                           





  

         



                                 





                                         

DRB3.2





                       

       



                                  



                



                    







        







               Bos taurus





                         



Unauthenticated | 197.161.200.41

Download Date | 10/29/13 8:40 AM

Mastitis resistance in dairy cattle 

  

         









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                             CXCR2

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               

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

                         

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







Podstawy genetyczne odporności krów mlecznych na zapalenie wymienia – artykuł przeglądowy



          

           

          

           

        







    



          

           



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Genetic Association of Polymorphism and Relative mRNA Expression of Tumor Necrosis Factor-Alpha Gene in Mastitis in Sahiwal Cow

Article

Full-text available

Jan 2021

Bovine mastitis is a host response to the microorganisms linked with the host immune system efficiency. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine that plays a significant role in the innate and adaptive immune response. In this study, we characterized the upstream regulatory region and evaluated the relative mRNA expression of TNF-α gene of Sahiwal cows. A single nucleotide polymorphism A>G was identified located within a sequence (MT_919286) at the 5´ upstream region. For gene expression, the ∆∆Ct was calculated by adjusting the target gene expression for the expression of the housekeeping gene (GAPDH) through real-time qPCR. The results revealed that relative mRNA expression of TNF-α most explains the change in the unit of ∆Ct and would result in a significantly higher expression of TNF-α gene in animals with mastitis. The relative mRNA expression of TNF-α gene was 35 and 9.53 times higher in animals with clinical and subclinical mastitis respectively, as compared to non-mastitic animals. The effect of the fold change of TNF-α and GAPDH was also assessed based on response surface methodology via Box Behnken design. The analysis depicted that all parameters had a significant impact on mastitis incidence in Sahiwal cows. This study would hopefully contribute towards a better understanding of the use of TNF-α gene marker as an authentic source of identification of severity of bovine mastitis. The findings of study may be helpful for the development of new strategies to control mastitis and preserve the health of dairy animals.

Genetic Evaluation of Susceptibility to and Recoverability from Mastitis in Dairy Cows

Thesis

Full-text available

Sep 2017

Berihu Welderufael

Mastitis has been the focus of many dairy cattle research projects over the last decades. However, in the genetic evaluation of udder health, only susceptibility to mastitis has been considered, leaving aside the other aspect of the disease - the recoverability. The aim of this thesis was to improve the genetic evaluation of udder health by introducing a new approach and models that can make use of the information contained in both directions: susceptibility to- and recoverability from mastitis. In paper I, extensive simulation analyses were performed to develop a bivariate model for joint genetic evaluations of susceptibility to- and recoverability from mastitis. In paper II, the bivariate model with an added time function as well as several systematic effects was applied to real data to estimate genetic parameters in Danish Holstein cows. In paper III, genome-wide association studies were conducted to identify associated single-nucleotide polymorphisms and thereof candidate genes. In paper IV, a dynamic health classification, which takes severity of possible infection into account was introduced to further improve the genetic evaluation of mastitis. Findings in paper I demonstrated that both traits can be modelled jointly and genetic parameters could be correctly reproduced. In paper II, we detected presence of genetic variation that resulted to heritability (ranging from 0.06 to 0.08) of similar size for both traits. The between trait genetic correlation was -0.83. Despite the strong negative genetic correlation, association signals in paper III did not overlap, suggesting that the traits are at least partially regulated by different genes. Complexity of the traits was manifested with the absence of strong association signals. In paper IV, considerable genetic variation was detected for cows’ presence in health classes defined for longer periods, whereas the variations in health classes defined for short-term and sudden changes (e.g., acute) were mostly attributed to environmental factors. Although susceptibility to- and recoverability from mastitis are strongly negatively correlated, recoverability which is as heritable as susceptibility could be considered a new trait for selection. Evaluating and modelling the ability of animals to overcome infection could be of specific benefit in situations of high disease incidence.

A Review on Bovine Mastitis with Special Focus on CD4 as a Potential Candidate Gene for Mastitis Resistance – A Review

Article

Full-text available

Jun 2020
ANN ANIM SCI

Mastitis is аn inflammation оf thе mammary gland, caused by the invasion and duplication оf Escherichia coli (E. coli) , Staphylococcus uberis (S. uberis) аnd Staphylococcus aureus (S. aureus) аnd а wide variety оf оthеr microorganisms thrоugh teat оr damaged nipple, decreasing potential milk production іn thе affected quarter оf mammary gland. Economic, animal productivity, international trade and animal welfare issues associated with mastitis play an important role in the agricultural industry. Therefore, worldwide dairy cattle breeding programmes are trying to breed cows wіth improved resistance tо mastitis. Mastitis can’t be eliminated but can be reduced to a low level. It can be achieved by breeding strategies, reducing the exposure to pathogen and increasing the resistance to intramammary infection. Numerous therapeutic, prophylactic аnd management techniques аrе uѕеd аѕ control and reduce the mastitis. However, а widely proposed strategy marker assisted selection uѕіng candidate gene approach which іѕ based оn improving thе host genetics. One of them is cluster of differentiation 4 ( CD4 ) gene, which is а glycoprotein located оn receptors оf immune cells. CD4 exhibit аn essential role іn a variety of inflammation related conditions іn mаnу species. Therefore, CD4 as a candidate gene for resistance to mastitis has received considerable attention. The review is based on a study of CD4 in association with improving resistance to mastitis and it may be helpful in formulating breeding programmes and marker assisted selection to lower the mastitis.

Associations between Bovine β-Defensin 4 Genotypes and Production Traits of Polish Holstein-Friesian Dairy Cattle

Article

Full-text available

Sep 2019

This study analyzed the associations between two single-nucleotide polymorphisms (C2239T and A1674C), used together as a genotype located in BNBD4, and milk traits and breeding values of productivity traits of Polish Holstein-Friesian dairy cows. The research was carried out on 322 cows, with 7070 milk parameter and somatic cell count records in daily milking, as well as 897 records covering data on whole lactations, and 2209 breeding value records for productivity traits. The DMU statistical package with a one-trait repeatability test-day animal model was used to estimate the associations. The differences between the genotype effects were analyzed using Duncan’s post-hoc tests. The CC/AA and CT/AC genotypes had the highest frequencies (0.62 and 0.23, respectively). For use in marker-assisted selection, the CC/AC genotype is the most promising as an indicator of high-yielding cows potentially resistant to mastitis, because it was associated with the lowest somatic cell count (SCC), highest milk, fat, and protein yields in daily milking, as well as with milk yield in the whole lactation. The studied genotypes were also related to the breeding values of all the investigated production traits. However, some simulation studies have indicated a high rate of false-positives in GWAS based on classically calculated EBVs.

Association of BoLA-DRB3 genotype with somatic cell count in milk of Polish Holstein cattle

Article

Full-text available

Jun 2018

The objective of this study was to evaluate the suitability of the BoLA-DRB3 gene polymorphism to define the phenotypic value of somatic cell count of 808 Polish Holstein cows. The cows were fathered by 190 sires. The PCR-RFLP alleles were identified with the BstYI, HaeIII, and RsaI restriction enzymes. For statistical analysis, 17 alleles whose frequencies in the herds were equal to or higher than 2% were selected. Somatic cell count was analyzed based either on the lactation averages or on test-day yields. Significant relationship between the occurrence of the BoLA-DRB3 gene alleles and somatic cell count were stated. In case of estimating the effects for all lactations together, the effect of substitution was observed for 11 alleles. The overall effects of four alleles (*12, *23, *24, and *ndb) were statistically significant and their effects were repeated in at least two lactations in the analysis of each lactation separately. The most numerous relationships were found for allele *24, which influences were statistically significant in lactations I to III in the analysis of all lactations together.

Computational analysis of non-synonymous SNPs in bovine Mx1 gene

Article

May 2018

Transcriptome profiling of Staphylococci-infected cow mammary gland parenchyma

Article

Full-text available

Jan 2017
BMC Vet Res

Modifications ciblées des génomes : Apports et impacts pour les espèces d’élevage

Article

Full-text available

Apr 2017

L’avènement des nucléases programmables, et de CRISPR-Cas9 en particulier, constitue une réelle rupture technologique dans le domaine de l’ingénierie génétique. Le principe de ces méthodes est relativement simple. Il consiste en premier lieu à générer des cassures double-brin au niveau de régions très précises d’une séquence cible (ADN d’une cellule somatique, germinale, embryonnaire, iPS...).Ces cassures sont ensuite réparées par des mécanismes cellulaires pouvant conduire à l’inactivation des régions modifiées (knock-out, ou KO), ou à l’insertion, par recombinaison homologue, d’un fragment de séquence modèle apporté à la cellule (knock-in, ou KI). Les domaines d’application de ces techniques sont très nombreux : recherche fondamentale, thérapie génique, ingénierie écologique, biotechnologies industrielles, agriculture, etc. Elles ont d’ores et déjà été utilisées à de multiples reprises dans les espèces animales d’élevage. Des exemples d’applications visant à améliorer la santé des animaux (induction de résistances pour des maladies infectieusesà fort impact économique, et/ou à fort potentiel zoonotique), à éviter des pratiques d’élevage compromettant le bien-être animal (écornage, élimination systématique de poussins mâles), ou à modifier les produits (lait, oeufs, viande) dans le but d’améliorer leur valeur santé (réduction des allergies), ou nutritionnelle, sont présentés. Le (techniques, réglementaires, économiques, éthiques...) qui sont discutées.

Transcriptome profiling of Staphylococci-infected cow mammary gland parenchyma

Article

Full-text available

Jun 2017
BMC Vet Res

Background Genome-wide gene expression profiling allows for identification of genes involved in the defense response of the host against pathogens. As presented here, transcriptomic analysis and bioinformatics tools were applied in order to identify genes expressed in the mammary gland parenchyma of cows naturally infected with coagulase-positive and coagulase-negative Staphylococci. Results In cows infected with coagulase-positive Staphylococci, being in 1st or 2nd lactation, 1700 differentially expressed genes (DEGs) were identified. However, examination of the 3rd or 4th lactations revealed 2200 DEGs. Gene ontology functional classification showed the molecular functions of the DEGs overrepresented the activity of cytokines, chemokines, and their receptors. In cows infected with coagulase-negative Staphylococci, in the 1st or 2nd lactations 418 DEGs, while in the 3rd or 4th lactations, 1200 DEGs were identified that involved in molecular functions such as protein, calcium ion and lipid binding, chemokine activity, and protein homodimerization. Gene network analysis showed DEGs associated with inflammation, cell migration, and immune response to infection, development of cells and tissues, and humoral responses to infections caused by both types of Staphylococci. Conclusion A coagulase-positive Staphylococci infection caused a markedly stronger host response than that of coagulase-negative, resulting in vastly increased DEGs. A significant increase in the expression of the FOS, TNF, and genes encoding the major histocompatibility complex proteins (MHC) was observed. It suggests these genes play a key role in the synchronization of the immune response of the cow’s parenchyma against mastitis-causing bacteria. Moreover, the following genes that belong to several physiological pathways (KEGG pathways) were selected for further studies as candidate genes of mammary gland immune response for use in Marker Assisted Selection (MAS): chemokine signaling pathway (CCL2, CXCL5, HCK, CCR1), cell adhesion molecules (CAMs) pathway (BOLA-DQA2, BOLA-DQA1, F11R, ITGAL, CD86), antigen processing and presentation pathway (CD8A, PDIA3, LGMN, IFI30, HSPA1A), and NOD-like receptor signaling pathway (TNF, IL8, IL18, NFKBIA).

Genetic Parameters for Clinical Mastitis, Fertility and Somatic Cell Score in Czech Holstein Cattle

Article

Full-text available

Jun 2017
ANN ANIM SCI

Cases of mastitis (CM) from 38,236 lactations belonging to 16,497 cows were recorded on seven farms in the Czech Republic from 1996 to 2014. Clinical mastitis was analyzed with linear animal model as an all-or-none trait for each recorded lactation (CM305) and separately for each trimester of lactation (CM1, CM2, and CM3). Bivariate linear animal models were used to estimate the genetic correlation between these CM traits and lactation means for somatic cell score (SCS305), the interval between calving and first insemination (INT) and days open (DO). Factors included in the linear model were parity, herd, year of calving, calving season, fixed linear and quadratic regression on age at first calving, fixed linear and quadratic regression on milk production in the corresponding parity, permanent environmental effect of the cow, and additive genetic effect of the cow. Estimated heritabilities of the CM traits ranged from 0.01 - 0.03. Permanent environmental effects accounted for approximately two-thirds of the phenotypic variance. Genetic correlations of SCS305 with CM traits were 0.85 ± 0.029, 0.81 ± 0.086, 0.82 ± 0.087, and 0.67 ± 0.088 for CM305, CM1, CM2, and CM3, respectively. Genetic correlations of INT with CM305, CM1, CM2, and CM3, respectively, were 0.22 ± 0.065, 0.19 ± 0.084, 0.20 ± 0.121 and 0.15 ± 0.121: and genetic correlations of DO and the four CM traits were 0.28 ± 0.079, 0.26 ± 0.101, 0.43 ± 0.134, and 0.15 ± 0.131. For the 140 sires in the dataset, Spearman rank correlations among breeding values for the four CM traits and for SCS305 were uniformly high 0.99 ± 0.001.

Association of bovine lactoferrin gene polymorphism with occurrence of mastitis

Article

Full-text available

Jan 2010
MILCHWISSENSCHAFT

Résumé/Abstract Several studies on the connection between lactoferrin gene polymorphism and mastitis susceptibility focused only on the phenotypic value of the somatic cell count as an indicator of mastitis and did not consider pathogens which cause inflammation. The objective of this study was to verify the hypothesis that polymorphism, occurring in intron 6 of the bovine lactoferrin gene is associated with estimated breeding values (EBV) of the somatic cell count (SCC) in milk and prevalence of sub-clinical mastitis caused by different ...

Genome-wide associations for milk production and somatic cell score in Holstein-Friesian cattle in Ireland

Article

Full-text available

Mar 2012
BMC GENET

Contemporary dairy breeding goals have broadened to include, along with milk production traits, a number of non-production-related traits in an effort to improve the overall functionality of the dairy cow. Increased indirect selection for resistance to mastitis, one of the most important production-related diseases in the dairy sector, via selection for reduced somatic cell count has been part of these broadened goals. A number of genome-wide association studies have identified genetic variants associated with milk production traits and mastitis resistance, however the majority of these studies have been based on animals which were predominantly kept in confinement and fed a concentrate-based diet (i.e. high-input production systems). This genome-wide association study aims to detect associations using genotypic and phenotypic data from Irish Holstein-Friesian cattle fed predominantly grazed grass in a pasture-based production system (low-input). Significant associations were detected for milk yield, fat yield, protein yield, fat percentage, protein percentage and somatic cell score using separate single-locus, frequentist and multi-locus, Bayesian approaches. These associations were detected using two separate populations of Holstein-Friesian sires and cows. In total, 1,529 and 37 associations were detected in the sires using a single SNP regression and a Bayesian method, respectively. There were 103 associations in common between the sires and cows across all the traits. As well as detecting associations within known QTL regions, a number of novel associations were detected; the most notable of these was a region of chromosome 13 associated with milk yield in the population of Holstein-Friesian sires. A total of 276 of novel SNPs were detected in the sires using a single SNP regression approach. Although obvious candidate genes may not be initially forthcoming, this study provides a preliminary framework upon which to identify the causal mechanisms underlying the various milk production traits and somatic cell score. Consequently this will deepen our understanding of how these traits are expressed.

A genome scan for QTL affecting milk somatic cell count in Israeli and Italian Holstein cows by means selective DNA pooling with multiple marker mapping

Article

Full-text available

Oct 2010
J DAIRY SCI

Mastitis is an important and common dairy cattle disease affecting milk yield, quality, and consumer safety as well as cheese yields and quality. Animal welfare and residues of the antibiotics used to treat mastitis cause public concern. Considerable genetic variation may allow selection for increased resistance to mastitis. Because of high genetic correlation to milk somatic cell score (SCS), SCS can serve as a surrogate trait for mastitis resistance. The present study intended to identify quantitative trait loci (QTL) affecting SCS in Israeli and Italian Holstein dairy cattle (IsH and ItH, respectively), using selective DNA pooling with single and multiple marker mapping. Milk samples of 4,788 daughters of 6 IsH and 7 ItH sires were used to construct sire-family high- and low-tail pools, which were genotyped at 123 (IsH) and 133 (ItH) microsatellite markers. Shadow correction was used to obtain pool allele frequency estimates. Frequency difference between the tails and empirical standard error of D, SE(D), were used to obtain P-values. All markers significant by single marker mapping were also significant by multiple marker mapping, but not vice versa. Combining both populations, 22 QTL on 21 chromosomes were identified; all corresponded to previous reports in the literature. Confidence intervals were set by chi-squared drop method. Heterozygosity of QTL was estimated at 44.2%. Allele substitution effects ranged from 1,782 to 4,930 cells/mL in estimated breeding value somatic cell count units. Most (80%) of the observed variation in estimated breeding value somatic cell score could be explained by the QTL identified under the stringent criteria. The results found here can be used as a basis for further genome-wide association studies for the same trait.

Frequencies and Effects of Alternative DRB3.2 Alleles of Bovine Lymphocyte Antigen for Holsteins in Milk Selection and Control Lines

Article

Full-text available

Jan 1998

Frequencies of alleles at the DRB3.2 locus of the bovine major histocompatibility complex for two genetic lines of Holsteins were compared, and allelic effects on yield and udder health traits were examined. The DRB3.2 genotypes of 186 cows and heifers were determined using DNA that had been extracted from blood samples. The cattle were from a designed selection experiment for milk yield. After edits, 173 cows and heifers with known alleles remained (54 from a control line and 119 from a selection line for milk yield). A total of 19 alternative DRB3.2 alleles appeared across the two lines, and frequencies ranged from 0.3 to 21.4%. Allelic frequencies differed significantly between the selection and control lines. Alleles 3, 8, 9, 10, 26, and 28 were more frequent in the control line, but alleles 16, 24, and 27 were more frequent in the selection line. An animal model was used to estimate gene substitution effects of alternative alleles on milk yield, fat yield, and protein yield, SCS, chronically elevated SCS, acutely elevated SCS, and mastitis incidence. First, second, and third lactations were analyzed separately. Allele 7 was associated with a significant increase in protein yield during first and second lactations and a significant increase in chronically elevated SCS and acutely elevated SCS during second lactation. Because of conflicting results with other studies and a limited numbers of cows, additional research is needed before specific alleles are confirmed to be associated with measures of yield and udder health.

Association of novel single nucleotide polymorphisms of the CXCR1 gene with the milk performance traits of Chinese native cattle

Article

Aug 2013
GENET MOL RES

Mastitis is an economically devastating disease affecting the dairy industry. Dairy cows with mastitis give reduced milk yield and produce milk that is unfit for consumption. The chemokine receptor CXCR1 is an excellent prospective genetic marker for mastitis resistance in cattle because it regulates neutrophil migration, killing, and survival during infection. We detected 4 single nucleotide polymorphisms (SNPs) of the CXCR1 gene in Chinese native cattle and analyzed their associations with milk traits. Screening for genetic variations in CXCR1 among 648 Chinese Holstein, Luxi Yellow, and Bohai Black cattle by created restriction site polymerase chain reaction (PCR), nested PCR, and DNA sequencing revealed 4 new SNPs with allelic frequencies ranging from 0.676 to 0.821, 0.706 to 0.803, 0.647 to 0.824, and 0.558 to 0.581. All four CXCR1 gene SNPs were located in exon II. Two SNPs, c.337A>G and c.365C>T, were nonsynonymous mutations [ATC (Ile) > GTC (Val) and GCC (Ala) > GTC (Val)], whereas two, c.291C>T and c.333C>T, were synonymous mutations [TTC (Gly) > TTT (Gly) and GGC (Phe) > GGT (Phe)]. Statistical analyses revealed the significant association of c.337A>G and c.365C>T with the somatic cell score, which suggests the possible role of these SNPs in the host response against mastitis. Our data suggest that combined genotypes CCAC/CCGC, CCAC/CTAT, and CCAT/CTAT (lowest somatic cell scores); CTAC/CTAT (highest protein rate); CCAC/CTGC (highest fat rate); and CCAT/CTAT (highest 305-day milk yield) can be used as possible candidates for marker-assisted selection in dairy cattle breeding programs.

The relationship between the variants of the bovine MBL2 gene and milk production traits, mastitis, serum MBL-C levels and complement activity

Article

Jun 2012

Mannose-binding lectin (MBL), a calcium-dependent collagenous lectin, plays an important role in the host immune defence against a wide range of pathogens. There are MBL1 and MBL2 genes which encode the MBL-A and MBL-C proteins, respectively. This study was carried out to investigate the relationship between the variants of the bovine MBL2 gene and milk production traits, mastitis, serum MBL-C levels and hemolytic complement activity in both classical pathway (CH50) and alternative pathway (ACH50) in Chinese Holstein cattle. Four single-nucleotide polymorphisms (SNPs) in the exon 1 of the MBL2 gene in Chinese Holstein cattle and Luxi yellow cattle were identified by the direct sequencing method. The SNP g.201 G>A was identified as a non-synonymous mutation (codon 31, Arg>Gln) at the N-terminus cysteine-rich domain and the SNPs g.234 C>A and g.235 G>A (codon 42) made Pro to Gln at the 1st Gly-X-Y repeat of the collagen-like domain, while the SNP g.244 T>C (codon 45) was identified as a synonymous mutation (Asn>Asn) at the 2 th Gly-X-Y repeat of the collagen-like domain. The SNP markers (g.201 G>A, and g.234 C>A) were significantly correlated with somatic cell score (SCS) (P<0.05). The concentration of MBL-C protein in serum ranges from 0.8 to 7.4 μg/mL by enzyme-linked immunosorbent assay. Six combinations of different haplotypes from the four SNPs were identified in Chinese Holstein cattle. Statistical analysis revealed that cows with the haplotype combination H4H5 exhibited the lowest SCS. The CH50 value of H4H5 and H5H5 cow are significantly higher than H2H5 haplotype combination (P<0.05). The association analysis results showed that the haplotype combination H4H5 may be used as a tolerance haplotype combination for the bovine mastitis.

Polymorphisms of the ATP1A1 gene associated with mastitis in dairy cattle

Article

Mar 2012
GENET MOL RES

Mastitis affects the concentrations of potassium and sodium in milk. Since sodium-potassium adenosine triphosphatase (Na(+), K(+)-ATPase) is critical for maintaining the homeostasis of these two ions, and is involved in cell apoptosis and pathogenesis, we presumed that polymorphism of the ATP1A1 gene, which encodes the bovine Na(+), K(+)-ATPase α1 subunit could be associated with mastitis. The ATP1A1 gene was analyzed in 320 Holstein cows using PCR low ionic strength single-strand conformation polymorphism (PCR-LIS-SSCP) and DNA sequencing methods. A C/A SNP was identified at nucleotide position -15,739 in exon 17 of the ATP1A1 gene, but it did not induce any change in amino acids. We examined a possible association of polymorphism of the ATP1A1 gene with somatic cell score and 305-day milk yields. Individuals with genotype CC in ATP1A1 had significantly lower somatic cell scores and 305-day milk yields than those with genotype CA. We also examined changes in Na(+), K(+)-ATPase activity of red cell membranes. The Na(+), K(+)-ATPase activity was significantly higher in dairy cows with genotype CC compared to the other two genotypes, and the Na(+), K(+)-ATPase activity of the resistant group was significantly higher than that of the susceptible group in dairy cows. We conclude that this polymorphism has potential as a marker for mastitis resistance in dairy cattle.

Genomic associations with somatic cell score in first-lactation Holstein cows

Article

Feb 2012
J DAIRY SCI

This genome-wide association study aimed to identify loci associated with lactation-average somatic cell score (LASCS) and the standard deviation of test-day somatic cell score (SCS-SD). It is one of the first studies to combine detailed phenotypic and genotypic cow data from research dairy herds located in different countries. The combined data set contained up to 52 individual test-days per lactation and thereby aimed to capture temporary increases in somatic cell score associated with infection. Phenotypic data for analysis consisted of 46,882 test-day records on 1,484 cows, and genotypic data consisted of 37,590 single nucleotide polymorphisms (SNP). Using an animal model, the associations between each individual SNP and the phenotypic data were estimated. To account for the risk of false positives, a false discovery rate threshold of 0.20 was set. The analyses showed that LASCS was significantly associated with a SNP on Bos taurus autosome (BTA) 4 and a SNP on BTA18. Likewise, SCS-SD was associated with this SNP on BTA18. In addition, SCS-SD significantly associated with a SNP on BTA6. Relatively few associations were found, suggesting that LASCS and SCS-SD are controlled by multiple loci distributed across the genome, each with a relatively small effect. Increased knowledge on genetic regulation of LASCS and SCS-SD may aid in identification of genes that play a role in mastitis resistance. Such knowledge helps us understand the genetic mechanisms leading to mastitis and in discovery of targets for mastitis therapeutics.

Quantitative trait loci for clinical mastitis on chromosomes 2, 6, 14 and 20 in Norwegian Red cattle

Article

Oct 2011
ANIM GENET

Mastitis is the most frequent and costly disease in dairy production and solutions leading to a reduction in the incidence of mastitis are highly demanded. Here a genome-wide association study was performed to identify polymorphisms affecting susceptibility to mastitis. Genotypes for 17 349 SNPs distributed across the 29 bovine autosomal chromosomes from a total of 2589 sires with 1 389 776 daughters with records on clinical mastitis were included in the analysis. Records of occurrence of clinical mastitis were divided into seven time periods in the first three lactations in order to identify quantitative trait loci affecting mastitis susceptibility in particular phases of lactation. The most convincing results from the association mapping were followed up and validated by a combined linkage disequilibrium and linkage analysis. The study revealed quantitative trait loci affecting occurrence of clinical mastitis in the periparturient period on chromosomes 2, 6 and 20 and a quantitative trait locus affecting occurrence of clinical mastitis in late lactation on chromosome 14. None of the quantitative trait loci for clinical mastitis detected in the study seemed to affect lactation average of somatic cell score. The SNPs highly associated with clinical mastitis lie near both the gene encoding interleukin 8 on chromosome 6 and the genes encoding the two interleukin 8 receptors on chromosome 2.

Associations between newly discovered polymorphisms in the Bos taurus growth hormone receptor gene and performance traits in Holstein-Friesian dairy cattle

Article

Feb 2011
ANIM GENET

Variations in the growth hormone receptor (GHR) gene sequence are associated with performance traits in cattle. For example, the single nucleotide polymorphism (SNP) F279Y in transmembrane exon 8 has a strong association with milk yield. In this study, 32 previously unreported, putative novel SNPs (31 in the 5' non-coding region) were identified by resequencing ∼19 kb of the GHR gene in genomic DNA from 22 cattle of multiple breeds. A population of 848 Holstein-Friesian AI sires was subsequently genotyped for the 32 putative novel SNPs and seven published SNPs (including F279Y, one in exon 1A promoter and five in exon 10). Associations between each segregating SNP and genetic merit for performance were quantified in the 848 Holstein-Friesians using weighted animal linear mixed models. Six of the published SNPs and seven of the novel SNPs were associated with at least one of the traits--milk yield, fat yield, protein yield, fat percentage, protein percentage, somatic cell score, calving interval, survival and growth and size traits. Even when the allelic substitution effect (P < 0.001) of F279Y was accounted for, the allelic substitution effect of one of the novel SNPs (GHR4.2) in the 5' non-coding region of GHR was associated with a lactation milk yield of 37.46 kg (P < 0.001). GHR4.2 and F279Y were not in linkage disequilibrium (r(2) = 0.00, D' = 0.04) in the 848 Holstein-Friesians, indicating that their association with milk yield was independent.

Genetic basis of mastitis resistance in dairy cattle – a review

Abstract

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