Marie-Etancelin C, Retailleau B, Alinier A, Vitezica Z G
J Anim Sci. 2015 Sep;93(9):4252-7. doi: 10.2527/jas.2015-9121.
Recent changes to French regulations now allow farmers to produce "foie gras" from both male and female mule ducks. The aim of this study was to assess the quality of female fatty liver and to compare, from a phenotypic and genetic point of view, liver quality in males and females. A total of 914 mule ducks (591 males and 323 females), hatched in a single pedigree batch, were reared until 86 d of age and then force-fed for 12 d, before being slaughtered. Carcasses and livers were weighed and liver quality was assessed by grading the extent of liver veining and measuring the liver melting rate, either after sterilization of 60 g of liver or pasteurization of 180 g of liver. Sexual dimorphism was observed in favor of males, with a difference of approximately 10% in carcass and liver weights and up to 54% for the liver melting rate. Moreover, one-third of female livers showed moderate to high veining, whereas this was not the case for male livers. The fatty livers of female mule ducks are, therefore, of poorer quality and could not be transformed into a product with the appellation "100% fatty liver." According to sex and parental line, heritability values ranged from 0.12 ± 0.05 to 0.18 ± 0.07 for fatty liver weight and from 0.09 ± 0.05 to 0.18 ± 0.05 for the 2 melting rate traits. The genetic correlations between the fatty liver weight and both melting rates were high (greater than +0.80) in the Muscovy population, whereas in the Pekin population, the liver weight and melting rates were less strongly correlated (estimates ranging from +0.36 ± 0.30 to +0.45 ± 0.28). Selection for lower liver melting rates without reducing the liver weight would, therefore, be easier to achieve in the Pekin population. Finally, as the 2 melting rate measurements are highly correlated (0.91 and over 0.95 for phenotypic and genetic correlations, respectively), we suggest using the easiest method, that is, sterilization of 60 g of liver.
法国法规最近的变化现在允许农民用公母骡鸭生产“肥肝”。本研究的目的是评估母鸭肥肝的质量，并从表型和遗传角度比较公母鸭肝脏的质量。总共914只骡鸭（591只公鸭和323只母鸭），来自同一谱系批次孵化，饲养至86日龄，然后强制填饲12天，之后屠宰。对胴体和肝脏进行称重，并通过对肝脏血管分布程度进行分级以及测量肝脏融化率来评估肝脏质量，肝脏融化率的测量是在对60克肝脏进行灭菌或对180克肝脏进行巴氏杀菌后进行的。观察到有利于公鸭的性别二态性，胴体和肝脏重量相差约10%，肝脏融化率相差高达54%。此外，三分之一的母鸭肝脏显示出中度至高度的血管分布，而公鸭肝脏则不然。因此，母骡鸭的肥肝质量较差，不能转化为标有“100%肥肝”名称的产品。根据性别和品系，肥肝重量的遗传力值范围为0.12±0.05至0.18±0.07，两个融化率性状的遗传力值范围为0.09±0.05至0.18±0.05。在番鸭群体中，肥肝重量与两个融化率之间的遗传相关性很高（大于+0.80），而在北京鸭群体中，肝脏重量与融化率的相关性较弱（估计值范围为+0.36±0.30至+0.45±0.28）。因此，在北京鸭群体中，选择降低肝脏融化率而不降低肝脏重量更容易实现。最后，由于两种融化率测量方法高度相关（表型相关性为0.91，遗传相关性分别超过0.95），我们建议使用最简单的方法，即对60克肝脏进行灭菌。
