Effect of Feeding Milled Brown Rice on Behavior and Meat Productivity of Forest-Grazing Pigs

Abstract

The effect of feeding milled brown rice on behavior and meat productivity of forest grazing pigs was investigated. An experiment was conducted in a woodland （30 a） of Kagoshima University Forest at Kagoshima-shi, Japan, from June to November, 2014. Eight pigs （average body weight, 44 kg; age, 19 weeks） were grazed using electric fence to separate groups, with each group comprising 4 pigs （1 hog and 3 gilts）. They were assigned to 2 treatments: 1） the control group was provided with commercial diet （CP 14-15％, TDN 77-78％）; and 2） the experimental group was given a mixed diet （commercial diet and milled brown rice: CP 9-13％, TDN 79-80％）. The percentages of brown rice to total diet at the first and the last fattening stages （19-29 w and 30-39 w） were 30％ and 70％, respectively. The amount of feed offered was 100％ of the TDN requirement for maintenance and growth according to the Japanese Feeding Standard for Swine （2013）. Feeding behavior was significantly smaller in the experimental group than in the control group at 22 weeks of age （P＜0.05）. In contrast, rooting behavior of the experimental group was higher than the control group （P＜0.05）. The final body weight was 107 kg for the control group and 104 kg for the experimental group at 39 weeks of age. The feed conversion ratios of the control and experimental groups during the experimental period were 5.2 and 5.3, respectively. The dressing percentage and rib-eye thickness were significantly smaller in the experimental group than in the control group （P＜0.05）. None of the other traits, such as carcass weight, rib thickness, and back fat thickness, were significantly different between the two groups. As for fatty acid composition of back fat, the percentage of oleic acid was higher in the experimental group than in the control group （P＜0.05）.

These results indicated that small-scale swine production in the woodland might be feasible in combination with milled brown rice, although it is necessary to study the appropriate feeding method of milled brown rice at the first fattening stage.