ペンシルベニア州立大学の乳牛遺伝学者、ホルスタインの子牛を脅かす変異遺伝子を発見(Penn State dairy cattle geneticist finds mutant gene threatening Holstein calves)

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2023-06-14 ペンシルベニア州立大学(PennState)

◆ホルスタインの子牛に影響を及ぼす「仔牛の床に伏す症候群」の原因を解明するため、Penn Stateの研究者は遺伝子解析を行いました。症状を示す子牛と健康な子牛を比較し、違いを特定。筋肉のカルシウムチャネルに関連する遺伝子の変異が影響を与えていることを発見しました。

◆この情報を基に、簡単な遺伝子検査を開発し、農場で使えるように商業化する計画です。この研究には、米国農務省の支援もありました。

<関連情報>

ホルスタイン種子牛の反すうに関連する推定ハプロタイプの同定 Identification of a putative haplotype associated with recumbency in Holstein calves

C.D. Dechow, E. Frye, F.P. Maunsell

JDS Communications  Available online: 6 August 2022

DOI:https://doi.org/10.3168/jdsc.2022-0224

ペンシルベニア州立大学の乳牛遺伝学者、ホルスタインの子牛を脅かす変異遺伝子を発見(Penn State dairy cattle geneticist finds mutant gene threatening Holstein calves)

Highlights

•Thirty-four calves on 4 farms were unable to stand without assistance with most calves not surviving beyond 6 weeks of age.

•An incompletely penetrant haplotype on chromosome 16 was identified as a possible cause of the recumbent phenotype.

•Additional studies are required to confirm the genetic origin of the condition and identify the causative mutation.

Abstract

Thirty-four Holstein calves from multiple farms were found recumbent during the neonatal period with no detectable neurologic, infectious, or metabolic abnormalities. Most calves did not survive beyond 6 wk of age. The objective of this study was to conduct a genome-wide association and pedigree analysis to determine if a genetic origin was plausible. There were 101,917 DNA markers for 18 affected calves and 26 unaffected family controls available for analysis. Genome-wide association, homozygosity screening, and a parental based transmission disequilibrium test were conducted in PLINK. A genomic region on the end of chromosome 16 that contained 78 markers based on a recessive inheritance model and that spanned 5.1 million bp was considered the most probable region for a genetic defect; the region was narrowed to 2.1 million bp following homozygosity screening and the transmission disequilibrium test with all affected calves homozygous in the candidate region and 1 homozygous control. A genotyped sire and 2 dams with imputed genotypes were heterozygous in the candidate region. A common sire born in 2008 was identified that was present for both paternal and maternal lineages of all affected calves; nearly all lineages traced through a prolific son born in 2010 who was genotyped and was heterozygous for the candidate region. Therefore, a possible genetic defect with incomplete penetrance on chromosome 16 that results in recumbency has been identified. Further efforts with an increase in families represented are needed to confirm a genetic basis, and identify the mutation and mode of inheritance.

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