MC4R gene polymorphisms for classification of growth efficiency and carcass measurements in two rabbit breeds in Egypt

Melanocortin 4 receptor (MC4R), a protein derived from the MC4R gene, is involved in feed intake, metabolism control, and body weight regulation in  humans. The purpose of this research was to explore MC4R polymorphisms alongside metabolic marker changes and their relationship with growth and  carcass measurements in rabbits. Using synthetic line V (V-line) and Baladi Black rabbit breeds (60 rabbits per breed), blood samples were collected for  DNA extraction and biochemical analysis. The polymerase chain reaction (PCR) product of MC4R (493 bp) revealed five nonsynonymous single nucleotide  polymorphisms (SNPs; submitted to GenBank with accession numbers gb|MT832144|, gb|MT832145|, and gb|MT832146|). Four SNPs were  characteristic of the V-line breed, and one was characteristic of the Baladi Black. For classification of the defined SNP-dependent groups within and  between breeds, a discriminant analysis model correctly classified a percentage of cases with the following predictor variables: 90.8% for body weight at  5–14 weeks of age; 85% for feed consumption, daily feed intake, and feed conversion ratio; and 93.3% for carcass measurements (for which hind part  weight, liver weight, and liver percentage were the best predictors in both breeds). There were significant differences between and within V-line and  Baladi Black breeds in agreement with metabolic biochemical marker profiles and the defined SNPs. The identified SNPs in the MC4R gene and profile of  the investigated metabolic biomarkers could be used as candidates and reference for the effective characterization of the two rabbit breeds. This study  could therefore facilitate the introduction of markerassisted selection for growth performance characteristics in rabbits.