The Asp298Asn missense mutation in the porcine melanocortin-4 receptor (MC4R) gene can be used to affect growth and carcass traits without an effect on meat quality

A promising tool to improve daily gain in pigs is the missense mutation (Asp298Asn) in the melanocortin-4 receptor (MC4R)gene, especially in the Belgian pig industry where the slow-growing Pie´train breed is very frequently used as the sire breed.The MC4R is expressed in the appetite-regulating region of the brain where it regulates feed intake and energy balance.The mutation has been associated with differences in fatness, daily gain and feed intake. However, less information on thecorrelated effects on meat quality is available. In order to evaluate the influence of theMC4R mutation on carcass and meatquality parameters, a total of 1155 pigs of a four-way cross were slaughtered at an average live weight of 109kg, and dataabout daily live-weight gain, carcass and meat quality were collected. Allelic frequencies were 0.69 for the G-allele (298Aspvariant or well-conserved variant) and 0.31 for the A-allele (298Asn variant or the mutated variant). Barrows and gilts werealmost equally distributed in this population with, respectively, 49.9% and 50.1%. Moreover, independent of this mutation,the relationship between average daily gain (ADG) and carcass on the one hand and meat quality traits on the other handwas evaluated in this population. A significant positive influence of theMC4R mutation on ADG (P,0.001) was found,accompanied by a higher fat thickness (P,0.05) and a lower carcass lean meat content (P,0.01), whereas muscle thicknessand carcass conformation traits were not affected. The effects on meat quality traits were not significant, except for a lowershear force (P50.054) and a higher intramuscular fat content (P50.052) in AA animals. In the longissimus, pH and porkquality meter (PQM) values were not influenced, and effects on drip loss and colour were not apparent. Residual correlationcoefficients between ADG and carcass lean meat content on the one hand and meat quality traits on the other hand weregenerally very low (|r|.0.1). Higher ADG, higher carcass fat thickness and lower carcass lean meat content were correlatedwith slightly lower shear force values (|r|