The impact of vitamin A restriction and ADH1C genotype on marbling in feedlot steers.
A novel SNP was discovered within the promoter region of alcohol dehydrogenase 1C (ADH1C c.-64T>C), the C allele eliminating a potential binding site for the transcription factor C/EPBα. The purpose of this study was to examine if an interaction between this SNP and vitamin A restriction had an effect on carcass characteristics in beef cattle. Following backgrounding on a β-carotene-deficient diet, 130 steers (50 TT, 50 CT, and 30 CC) were finished for 5 mo and received either no supplemental vitamin A (unsupplemented) or 750,000 IU/mo (supplemented). A subgroup of 5 steers • genotype(-1) • treatment(-1) was randomly selected for pre- and postfinishing liver biopsies to assess vitamin A status and measure gene expression. Unsupplemented steers (Bos taurus) had significantly greater (P < 0.05) marbling scores than supplemented steers. There was a significant interaction between genotype and vitamin A supplementation on ether-extractable intramuscular fat (IMF). Within the unsupplemented treatment, TT steers had nearly 23% greater IMF than CC steers. Additionally, unsupplemented TT steers had over 24% greater IMF than supplemented TT steers. Expression of ADH1C in the liver was additive with each additional T allele, potentially due to the elimination of a possible binding site for C/EBPα. It is plausible that CC cattle have reduced ability to metabolize retinol to retinaldehyde (and subsequently retinoic acid) and that a phenotypic effect is only observed when vitamin A is limiting. Therefore, ADH1C c.-64T>C genotype, in combination with reduced vitamin A supplementation, could potentially be implemented in marker-assisted management to maximize marbling in finishing cattle.
Department of Animal and Poultry Science, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon S7N5A8, Canada.
A K
AK
Ward
J J
JJ
McKinnon
S
S
Hendrick
F C
FC
Buchanan
D000273:Adipose Tissue / Q000502:physiology; D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001823:Body Composition / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D002417:Cattle / Q000235:genetics* / Q000502:physiology*; D019587:Dietary Supplements; D015971:Gene Expression Regulation, Enzymologic; D005819:Genetic Markers; D005838:Genotype; D008099:Liver / Q000378:metabolism; D008297:Male; D053589:Nuchal Cord; D011485:Protein Binding; D014801:Vitamin A / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
D005819:Genetic Markers; D014801:Vitamin A; D000426:Alcohol Dehydrogenase