Are meat and carcass quality in commercial growing finishing gilts and entire males affected by a polymorphism of the MC4R gene?

Alice Van den Broeke, Marijke Aluwé, Frank Tuyttens, Steven Janssens, Annelies Coussé, Lynn Vanhaecke, Nadine Buys, Sam Millet

    Onderzoeksoutput: Bijdrage aan congresPaper

    Uittreksel

    Introduction
    Societal pressure to raise entire male pigs is growing in Belgium and many other EU-countries. A disadvantage of raising entire male pigs is the possible presence of boar taint, an off-odour present in heated meat or fat. Genetic selection which decreases the incidence of boar taint without negative effects on growth and meat characteristics could help pig farmers to shift towards raising entire males.
    The melanocortin-4 receptor (MC4R), a G protein-coupled transmembrane receptor expressed on the surface of neurons throughout the brain, plays an important role in the regulation of the energy balance and body composition (1). In pigs, the Asp298Asn polymorphism is associated with increased feed intake, increased daily gain leading to lower lean meat content. English breeds, selected towards a high daily gain, have a high allelic frequency of the A allele in contrast to the Belgian breeds that are selected towards lean meat and have a high G allele frequency (2). This marker has also been linked to the presence of boar taint, with higher levels in animals carrying the Asp298Asn polymorphism (unpublished results). The aim of this study, therefore, was to assess if genetic selection towards less boar taint is possible using this marker in commercial entire males and gilts without compromising growth performances and meat quality.

    Material and Methods
    In an interventional study, boars and gilts of the homozygous genotype AA were compared to boars and gilts of the homozygous genotype GG. Littermates of AG x AG litters (Rattlerow-Seghers hybrid sows X Piétrain boars) with the desired genotype were divided in the four treatment groups. In eleven consecutive rounds, six weaned pigs per homozygous genotype and per gender were selected and housed together in one pen. The pigs had free access to water and were fed ad libitum with a four phase diet adapted to their requirements. They were slaughtered per pen at an intended average live weight of 110 kg. The pigs were fastened one day prior to the slaughter day and slaughtered in a commercial slaughterhouse by carbon dioxide stunning followed by exsanguination. All pigs were weighted individually and feed consumption per pen was recorded weekly in order to calculate average daily gain per animal and average daily feed intake and feed conversion ratio per pen per week. Boar taint was measured in neck fat samples collected 45 minutes post mortem by a sensory evaluation using the hot iron method (3). At 45 minutes and 24 hours postmortem, the pH was measured in the musculus longissimus thoracis et lumborum (mLT) around the 13th rib of the right carcass side. Drip loss was also assessed (48 hours at 4°C). Color was determined with a reflection spectrophotometer (HunterLab Miniscan). Furthermore, intramuscular fat content was calculated based on the total amount of lipids present as determined using the modified Bligh and Dyer method in a slice with all visible fat removed. Cooking loss was recorded as proportion of weight loss during cooking at 75 °C for 60 minutes. Tenderness was evaluated by shear force determination on a cooked slice of meat with a triangular Warner Bratzler shear force measurement device. Dressing percentage was calculated as cold carcass weight, recorded in the slaughterhouse, divided by live weight, recorded prior to transport to the slaughterhouse. Muscle thickness and fat thickness were measured using a Capteur Gras-Maigre (CGM)-device. The values measured with the CGM device were converted into meat percentage by the equation approved for use in Belgian abattoirs by the regulation 2012/416/EU (4). Furthermore, the ham angle and ham width were measured using a Pic2000 device. All meat and carcass quality measurements and daily gain were analyzed by ANOVA (Statistica 11, Statsoft, USA), with animal as the experimental unit and gender and genotype and gender x genotype interaction as fixed factors. Average daily feed intake and feed conversion ratio were analyzed by ANOVA (Statistica 11, Statsoft, USA), with pen as the experimental unit and gender and genotype and gender x genotype interaction as fixed factors.
    Results and Discussion
    The MC4R marker has a significant effect on several performance characteristics. The average daily feed intake was significant higher (P<0.05) in AA animals compared to GG animals. The daily gain of the AA entire males was also significantly higher compared to GG males (P<0.01). Results of the entire males are similar to those reported by Van den Maagdenberg and coworkers (2) in gilts and barrows. The sensory analysis of boar taint revealed no significant difference between AA and GG entire males. The polymorphism did not affect any of the meat quality characteristics analyzed in this study but gender had an effect on pH 45, color L*, color B* and cooking loss. Body composition differed considerably between treatment groups. Backfat thickness was significantly higher (P<0.01) and muscle thickness was significant lower (P<0.01) in AA than in GG pigs. Consequently, estimated lean meat percentage was lower in AA pigs. The ham width was also significantly higher (P<0.05) in GG pigs. Dressing percentage of AA pigs was significantly lower than those of GG pigs (P<0.05). The conformation was significantly better in GG animals (P<0.01). Gender had an effect on almost all carcass quality parameters.

    Conclusion
    These results suggest that the MC4R gene has an effect on performance parameters, carcass quality but not on meat quality. A significant difference in boar taint between AA and GG entire males could not be determined.
    TaalEngels
    Aantal pagina's2
    StatusGepubliceerd - 10-dec-2013
    EvenementBAMST Symposium 2013 - Kortrijk, België
    Duur: 10-dec-201310-dec-2013

    Symposium

    SymposiumBAMST Symposium 2013
    LandBelgië
    StadKortrijk
    Periode10/12/1310/12/13

    Dit citeren