We evaluated the effects of feeding milled brown rice on the meat productivity of forest-grazing pigs. An experiment was conducted in a woodland (20a) in Kagoshima-shi, Japan, from May to December 2013. Eight hogs (average body weight, 28kg ; age, 18 weeks) were allowed to graze in 2 groups separated using an electric fence with each group comprising 4 pigs. They were assigned to 2 treatments, where the 1) control group was provided with commercial diet (crude protein [CP] 14-15%, total digestible nutrients [TDN] 77-78%) and the 2) experimental group was given fermented diet (60% milled brown rice, 20% screened sweet potato, and 20% rice bran : CP 8% and TDN 69%). This amount of feed satisfied 100% of the TDN requirement set by the Japanese Feeding Standard for Swine (2013). Resting and feeding behaviors were significantly less intense in the experimental group than in the control group on days 9 and 75 (P<0.05). In contrast, rooting behavior in the experimental group was more intense than that in the control group on days 9 and 75 (P<0.05). The body weight after 25 weeks was significantly less in the experimental group than in the control group (P<0.05). The final body weight was 109kg for the control group (at week 37) and 98kg for the experimental group (at week 46). The feed conversion ratios for the control and experimental groups during the experimental period were 4.6 and 8.4, respectively. The rib eye and rib were significantly thinner in the experimental group (P<0.05), while none of the carcass yield traits, such as carcass weight or dressing percentage, was significantly different between the two groups. The experimental group showed a low preference to milled brown rice, thereby feed efficiency at the first fattening stage (30-70kg) was also lower in this group than in the control group. However, there were no differences in the daily gain and feed conversion ratios between the two groups at the last stage (over 70kg).
These results indicate that small-scale swine production in woodlands can be feasible if combined with self-supplied feed, including milled brown rice. Nevertheless, it is necessary to study more appropriate methods of feeding milled brown rice to swine at the first fattening stage.