Hiroyuki Hirooka

Jinhua pigs have excellent meat quality and intramuscular fat content (IMF). Crossbreeding of Jinhua with Duroc pigs with high productivity was conducted to develop a new composite breed that possesses the beneficial characteristics of both breeds. The objective of this study was to estimate the crossbreeding parameters (additive breed, dominance, and epistatic loss effects) using the Kinghorn model and genetic parameters (heritability and genetic correlation) for carcass and meat quality traits by analysing the phenotypic data of Jinhua, Duroc, and their crossbred pigs. Backfat thickness at the thinnest point above the 9th to 13th thoracic vertebrae (BF), longissimus muscle area between the 4th and 5th thoracic vertebrae (LMA), meat shear force value (SFV), and IMF were measured. The additive breed effects were significant for all traits: 1.59 cm, −8.30 cm 2 , −6.38 lb/cm 2 , and 1.76% for BF, LMA, SFV, and IMF, respectively. The dominance effect was significant for LMA (7.41 cm 2 ) and IMF (−2.46%), whereas the epistatic loss effect was significant for only LMA (−15.18 cm 2 ). The estimated heritability values were high, ranging from 0.58 for IMF to 0.76 for LMA. A negative but non‐significant genetic correlation of −0.11 was estimated between BF and IMF; however, previous studies have reported that the genetic correlation between these traits is moderately positive in modern western pigs. Our results imply that, with the estimation of crossbreeding and genetic parameters, genetic improvement could be implemented to produce a new composite breed with good meat quality and productivity, to meet Japanese market requirements, by crossbreeding Jinhua and Duroc pigs.