Breed characteristics of indigenous Okinawan Agu pigs analyzed by body measurements and reproductive traits

Agu, a relatively small-bodied pig with a black coat, is indigenous to Okinawa the southern most island in Japan. Body measurements (n = 1,164) and reproductive traits of Agu pigs were investigated to reveal breed characteristics. European breeds were introduced into Okinawa and might have been crossed with Agu pigs to improve their economic traits ; nevertheless, body measurements of the breed have remained unchanged for 50 years. Principal component analysis was conducted to compare the characteristics of the Agu breed with Chinese breeds (Short-ear, Taoyuan, Putian, Meishan, Fushian Black, Min) and European breeds (Berkshire, Landrace, Hampshire, Large White, Duroc). The first principal component was the size, and the second the shape, which differentiated body shape by contrasting body length versus chest girth. Agu pigs were similar in size to Puitan, Jinhu and Taoyan, the medium-sized Chinese breeds. The body shape was different, however ; Agu pigs had a stubby shape and a thick chest girth compared with their body length. Reproduction records of Agu sows and European breeds (Landrace, Landrace * Large White or Large White * Landrace) were analyzed to determine breed types. Analysis of variance with a linear model including the effect of breeds of sows, parity and year-seasons of farrowing down showed that the breed effect was significant in the following traits : number of implanted fetuses (NIF), total number born (TNB), number born alive (NBA) and number weaned (NW), number of stillborn piglets (NSB), survival rate at weaned (SVW) and percentage of mummified fetuses (PMF). The interaction effect between breed and parity was significant only in SVW. The least square mean showed the following : NIF, TNB, NBA and NW of Agu sows was 5.2, 4.8, 4.1 and 3.3, respectively, which was smaller than half the number of European breeds ; Agu sows had lower SVB, SVW and higher PMF than European breeds; SVW of Agu sows at 1sup(st), 5sup(th) and higher parity was lower than that of the parity of other breeds. The least square means of average weaning weight (AWW) and litter weaning weight (LWW) were lower in Agu sows than those in European breeds.