Genetic analyses and quantitative trait loci detection, using a partial genome scan, for intramuscular fatty acid composition in Scottish Blackface sheep

E. Karamichou, R. I. Richardson, G. R. Nute, K. P. Gibson, S. C. Bishop*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Genetic parameters for LM fatty acid composition were estimated in Scottish Blackface sheep, previously divergently selected for carcass lean content (LEAN and FAT lines). Furthermore, QTL were identified for the same fatty acids. Fatty acid phenotypic measurements were made on 350 male lambs, at approximately 8 mo of age, and 300 of these lambs were genotyped across candidate regions on chromosomes 1, 2, 3, 5, 14, 18, 20, and 21. Fatty acid composition measurements included in total 17 fatty acids of 3 categories: saturated, monounsaturated, and polyunsaturated. Total i.m. fat content was estimated as the sum, of the fatty acids. The FAT line had a greater i.m. fat, content and more oleic acid, but less linoleic acid (18:2 n-6) and docosapentaenoic acid (22:5 n-3) than did the. LEAN line. Saturated fatty acids were moderately heritable, ranging from 0.19 to 0.29, and total SFA were highly heritable (0.90). Monounsaturated fatty acids were moderately to highly heritable, with cis-vaccenic. acid (18:1 n-7) being the most heritable (0.67), and total. MUFA were highly heritable (0.73). Polyunsaturated fatty acids were also moderately to highly heritable; arachidonic acid (20:4 n-6) and CLA were the most heritable, with values of 0.60 and 0.48, respectively. The total PUFA were moderately heritable (0.40). The QTL analyses were performed using regression interval mapping techniques. In total, 21 chromosome-wide QTL were detected in 6 out of 8 chromosomal regions. The chromosome-wide, significant QTL affected 3 SFA, 5 MUFA, and 13 PUFA. The most significant result was a QTL affecting linolenic acid (18:3 n-3) on chromosome 2. This QTL segregated in 2 of the 9 families and explained 37.6% of the phenotypic variance. Also, 10 significant QTL were identified on chromosome 21, where 8 out of 10 QTL were segregating in the same families and detected at the same position. The results of this study demonstrate that altering carcass fatness will simultaneously change i.m. fat content and oleic, linoleic, and docosapentaenoic acid content. The heritabilities of the fatty acids indicate opportunities for genetically altering most fatty acids. Moreover, this is the first report of detection of QTL directly affecting fatty acid composition in sheep.

Original languageEnglish
Pages (from-to)3228-3238
Number of pages11
JournalJournal of Animal Science
Volume84
Issue number12
DOIs
Publication statusPublished - Dec 2006

Keywords

  • fatty acid
  • genetic parameter
  • intramuscular fat
  • quantitative trait locus
  • sheep
  • CONJUGATED LINOLEIC-ACID
  • MEAT QUALITY TRAITS
  • RAY COMPUTER-TOMOGRAPHY
  • CARCASS COMPOSITION
  • CONFIDENCE-INTERVALS
  • ADIPOSE-TISSUE
  • PLASMA-LIPIDS
  • STEARIC-ACID
  • LIVE WEIGHT
  • TEXEL SHEEP

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