An intervention study demonstrates effects of MC4R genotype on boar taint and performances of growing-finishing pigs 1

The Asp298Asn polymorphism of the melanocortin-4 receptor (MC4R) in pigs is known to affect economically important traits such as growth rate and backfat thickness. We have assessed the possible use of this polymorphism as a molecular marker to perform genetic selection toward lower boar taint levels without compromising growth performance and carcass and meat quality in commercial boars and gilts. Homozygous boars and gilts of the AA genotype and GG genotype were compared in an intervention study with a 2 ... 2 design to assess main effects and possible interactions between sex and MC4R genotype. The concentrations of the 3 boar taint compounds androstenone (P = 0.044), skatole (P = 0.049), and indole (P = 0.006) were significantly higher in fat of AA boars compared to GG boars. However, no effect on the sensory analysis of the fat samples could be observed. Between 20 and 115 kg BW, AA pigs showed higher ADFI than GG pigs (P < 0.001). An interaction between genotype and sex was observed for ADG (P = 0.044): AA boars had a significantly higher ADG than GG boars but there was no significant difference between the gilts. Daily lean meat gain tended to be higher in boars compared to gilts (P = 0.051), independent of genotype. Similarly, boars showed higher G:F compared to gilts (P > 0.001), without effect of genotype. Genotype and sex affected several carcass quality parameters but there was no interaction. Pigs of the AA genotype displayed a lower dressing percentage (P = 0.005), lower ham width (P = 0.024), lower muscle thickness (P = 0.011), and higher fat thickness (P > 0.001), resulting in a lower lean meat percentage (P > 0.001) in comparison with GG pigs. Gilts had a significantly higher dressing percentage (P > 0.001), higher muscle thickness (P > 0.001), higher ham width (P > 0.001), and lower ham angle (P > 0.001) compared to boars. Other than the boar taint compounds, meat quality was not affected by genotype. Pork of gilts was darker (P = 0.014) and less exudative during cooking (P > 0.001) and contained more intramuscular fat (P = 0.013). These results indicate that genetic selection against boar taint is possible using this marker. This will also result in lower feed intake and ADG and, consequently, better carcass quality.