Growth Patterns and Developmental Changes of Backfat Thickness in Okinawa Agu Gilts

Abstract

This study clarified the growth patterns and developmental changes of the backfat thickness (BF) of Okinawa Agu gilts regarding their management. Five nonlinear growth models (Logistic, Gompertz, von Bertalanffy, Richards, and Janoschek) were used to describe growth patterns. Weekly, body weight (BW) data from birth to 34 weeks of age were collected. BF at the P2 position from 4 to 34 weeks of age was recorded every 4-5 weeks. Among 23 gilts pigs, 14 were Agu pigs, and nine were Landrace pigs. Animals were allowed fed ad libitum to 16 weeks of age and then reared under restricted feeding (1.3 kg/day for Agu gilts : 2.5 kg/day for Landrace gilts) to 34 weeks of age. Comparison among the five models revealed that the Richards model was the best fit for the growth data based on adjusted R-square (AdjR²) and Akaike’s information criterion (AIC) for both breeds. The Agu gilts showed smaller mature BW, early maturing rate, and earlier weeks of age at the inflection point than Landrace gilts. BF development in Agu gilts was rapid during 4-16 weeks of age under ad libitum feeding but was suppressed after 16 weeks of age under restricted feeding. The breed differences of BF were observed from 8 weeks of age, and Agu gilts had thicker BF than Landrace gilts.