Evidence of major gene(s) affecting milk traits in the Chios sheep breed

Chatziplis, Dimitrios; Tzamaloukas, Ouranios; Miltiadou, Despoina; Ligda, Christina; Koumas, A.; Mavrogenis, A. P.; Georgoudis, A.; Papachristoforou, C.

doi:10.1016/j.smallrumres.2011.12.009

Cited by 5 publications

(6 citation statements)

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“…For the analysis of first to third lactation records, the proportion of both milk yield and FCM phenotypic variance due to permanent animal effect was found to be 0.10 ± 0.02. Heritability estimates generally agreed with previous calculations of milk yield heritability in the ARI flock (Mavrogenis, 1982;Mavrogenis and Papachristoforou, 1988;Chatziplis et al, 2012), in other Chios sheep populations (Ligda et al, 2000) and other sheep breeds (Othmane et al, 2002b).…”

Section: Resultssupporting

confidence: 85%

A single nucleotide polymorphism in the acetyl-coenzyme A acyltransferase 2 (ACAA2) gene is associated with milk yield in Chios sheep

Orford

Hadjipavlou

Tzamaloukas

et al. 2012

Journal of Dairy Science

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The objective of this work was to identify single nucleotide polymorphisms (SNP) in the ovine acetyl-coenzyme A acyltransferase 2 (ACAA2) gene and investigate their association with milk production traits. Molecular characterization was accomplished by sequencing the entire coding region and the 3' and 5' untranslated regions (UTR) of the ACAA2 gene from individuals of the Chios sheep bred in Cyprus. All exons appeared to be monomorphic except for the last exon, for which a single SNP located in the 3' UTR of the gene (HM537015:g.2982T>C) was detected. Mixed model association analysis, using SNP data from 318 animals from 104 paternal half-sib families and first-lactation phenotype and pedigree information on 2,405 ewes revealed that this SNP was significantly associated with milk yield. The significance of the SNP effect persisted when milk yield information up to the third lactation was analyzed. Both alleles at the locus segregated at similar frequencies. The T allele was associated with increased milk yield and exhibited partial dominant action. Animals with the g.2982TT or g.2982CT genotype had significantly higher milk yield than those with the g.2982CC genotype, with the g.2982T allele having an additive effect of 13.4 (± 4.7) kg and a dominance effect of 7.9 (± 6.1) kg. Based on estimated allelic effects and sample allele frequencies, the g.2982T>C SNP explained 10% of the additive genetic variance for milk yield. A putative mode of action through nutrient metabolism is discussed.

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Section: Resultssupporting

confidence: 85%

A single nucleotide polymorphism in the acetyl-coenzyme A acyltransferase 2 (ACAA2) gene is associated with milk yield in Chios sheep

Orford

Hadjipavlou

Tzamaloukas

et al. 2012

Journal of Dairy Science

Self Cite

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“…The only QTL reported here for the first time is on chromosome 19, which attained the highest significance level in the present study. These results are also consistent with a previous study of Chios sheep [60], suggesting that a relatively major locus might be involved in ovine milk production. Nevertheless, these SNPs were not associated with any of the studied mastitis traits.…”

Section: Discussionsupporting

confidence: 93%

Genetic and genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep

et al. 2019

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Milk yield is the most important dairy sheep trait and constitutes the key genetic improvement goal via selective breeding. Mastitis is one of the most prevalent diseases, significantly impacting on animal welfare, milk yield and quality, while incurring substantial costs. Our objectives were to determine the feasibility of a concomitant genetic improvement programme for enhanced milk production and resistance to mastitis. Individual records for milk yield, and four mastitis-related traits (milk somatic cell count, California Mastitis Test score, total viable bacterial count in milk and clinical mastitis presence) were collected monthly throughout lactation for 609 ewes of the Chios breed. All ewes were genotyped with a mastitis specific custom-made 960 single nucleotide polymorphism (SNP) array. We performed targeted genomic association studies, (co)variance component estimation and pathway enrichment analysis, and characterised gene expression levels and the extent of allelic expression imbalance. Presence of heritable variation for milk yield was confirmed. There was no significant genetic correlation between milk yield and mastitis traits. Environmental factors appeared to favour both milk production and udder health. There were no overlapping of SNPs associated with mastitis resistance and milk yield in Chios sheep. Furthermore, four distinct Quantitative Trait Loci (QTLs) affecting milk yield were detected on chromosomes 2, 12, 16 and 19, in locations other than those previously identified to affect mastitis resistance. Five genes (DNAJA1, GHR, LYPLA1, NUP35 and OXCT1) located within the QTL regions were highly expressed in both the mammary gland and milk transcriptome, suggesting involvement in milk synthesis and production. Furthermore, the expression of two of these genes (NUP35 and OXCT1) was enriched in immune tissues implying a potentially pleiotropic effect or likely role in milk production during udder infection, which needs to be further elucidated in future studies. In conclusion, the absence of genetic antagonism between milk yield and mastitis resistance suggests that simultaneous genetic improvement of both traits be achievable.

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“…To the best of our knowledge, the QTL on chromosome 19 is reported here for the first time. These results are also consistent with a previous study of Chios sheep [54], suggesting that a relatively major locus might be involved in ovine milk production. The QTL identified on chromosome 19 in the present study explained 16% of the genetic variance.…”

Section: Discussionsupporting

confidence: 93%

Genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep

Banos

Clark

Bush

et al. 2019

Preprint

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24Milk yield is the most important dairy sheep trait and constitutes the key genetic improvement 25 goal via selective breeding. Mastitis is one of the most prevalent diseases, significantly 65 Page4 66Beyond simply increasing milk production, the dairy sheep industry faces challenges such as 67 the need to offer healthy products to consumers, addressing animal welfare, and ensuring the 68 long-term competitiveness and sustainability of the sector. Mastitis is the most prevalent and 69 costly disease in the dairy industry due to reduced and discarded milk, early involuntary culling 70 of animals, and veterinary services and labour costs [6, 7]. The disease also poses a potential 71 threat of zoonosis and antimicrobial resistance if antibiotic treatment is not applied carefully 72 [6][7][8]. Moreover, mastitis is a welfare concern because of associated pain, anxiety and 73 restlessness, and upsets the normal feeding behaviour of the animals [9]. Host resistance to 74 mastitis is a moderately heritable trait [7]. Recently, an ovine custom made mastitis specific 75 960-SNP DNA array was built to facilitate genetic selection and improvement of animal 76 resistance to mastitis in dairy sheep [10] [11] [12] [13]. We previously used this array in a 77 genomic association study and detected five quantitative trait loci (QTLs) for mastitis 78 resistance in Chios sheep [10]. 80In the present study, we examined the genetic and genomic relationship between milk yield 81 and mastitis resistance in the Chios sheep, using pedigree and genomic information. The 82 relationship between the two traits is crucial if mastitis resistance is to be included in selective 83 breeding goals together with increased milk yield. We estimated genetic parameters and 84 investigated whether relevant QTLs for milk yield exist in previously identified mastitis-85 specific genomic regions. We also performed pathway analysis and examined gene expression 86 and allelic expression imbalance to characterise the genes located under the QTL regions in 87 relation with milk yield and mastitis resistance. 88 Page5 89 Materials and Methods 90 91 Ethical statement 92 The study was approved by the Ethics and Research Committee of the Faculty of Veterinary 93 Medicine, Aristotle University of Thessaloniki, Greece. Permits for access and use of the 94 commercial farms were granted by the farm owners, who were members of the Chios Sheep 95 Breeders' Cooperative "Macedonia". During sampling, animals were handled by qualified 96 veterinarians. Permission to qualified veterinarians to perform milk and blood sampling was 97 granted by the National (Greek) Legislature for the Veterinary Profession, No. 344/29-12-98 2000. 99 100 Animals, sampling and phenotyping 101 Animals used in the present study included 609 purebred Chios dairy ewes raised in four 102 commercial farms in Greece. Complete pedigree data were available for these animals. Ewes 103 were in their first or second lactation. Daily milk yield was recorded on each animal on the day 104 of monthly visits t...

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Evidence of major gene(s) affecting milk traits in the Chios sheep breed

Cited by 5 publications

References 30 publications

A single nucleotide polymorphism in the acetyl-coenzyme A acyltransferase 2 (ACAA2) gene is associated with milk yield in Chios sheep

A single nucleotide polymorphism in the acetyl-coenzyme A acyltransferase 2 (ACAA2) gene is associated with milk yield in Chios sheep

Genetic and genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep

Genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep

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