Effects of graded replacement of corn by brown rice in diet containing barley and tea manufacturing residual on growth performance and meat quality of finishing pigs in summer

We examined the effects of blending ratios of brown rice in diets containing barley and residual from processed tea on growth performance and meat quality of finishing pigs under high ambient temperatures. Brown rice ground to less than 2mm was used as substitute for corn in the diet. Total of 24 castrated LWD pigs were used in this study. The pigs were divided into 4 groups, which were fed with experimental diets containing brown rice at the ratio of 0, 10, 20, and 40%, and these diets contained 15% barley and 1% tea residual. The pigs were housed three per pen during the summer season with body weight averages from 70.9kg to 110kg. In growth performance, although no significant difference was observed, feed conversion ratio was lower as the blending ratio of brown rice was increased. In carcass traits, 10% brown rice blend group had significantly lower carcass yield in comparison with 0% brown rice blend group. The back fat thickness (loin) of the 10% brown rice blend group was significantly lower than that of the 0% brown rice blend group. Those of 20% and 40% brown rice blend groups had also lower values but significant differences were not observed. In meat quality such as water holding capacity and fat melting temperature, a significant difference was not observed. However, shear value of the 40% brown rice blend group was significantly lower than that of the 20% brown rice blend group. In fatty acid composition of subcutaneous fat, palmitic acid of the 40% brown rice blend group was higher than that of the other groups, and oleic acid of the 40% brown rice blend group was also higher than that of the 0% and 10% brown rice blend group. In free amino acid composition of loin, no significant difference was observed. For oxidative stress markers, 20% and 40% brown rice groups had high levels of the plasma total anti-oxidative status and low levels of thiobarbituric acid reactive substances (TEARS), though no significant difference was observed.