Effect of heating brown rice and unhulled rice liquid feed on growth performance and meat quality in finishing pigs

In this experiment, we examined the effects of heat-treated rice-based liquid feed on the digestibility, growth performance, and meat quality in finishing pigs. The feed for pigs was prepared using brown rice, unhulled rice, soybean meal, and potato chip residue as the main materials, with vitamin/minerals additives as supplements. The experimental feed included the following: dry feed as a control treatment; liquid feed prepared by adding water to the dry feed at a weight ratio of 3:1 (denoted here as LF treatment); and heat-treated LF feed at 70°C for 120 min (as the HLF treatment). Four pigs with an average body weight of 73.0 kg for each treatment were fed ad libitum for 35 days. Digestibility was measured by fecal collection on days 11-15 of the experiment. The results showed no difference in the digestibility of dry matter, crude protein, ether extract, or gross energy among the treatments. The dry matter intake in LF treatment was lower than that of the control and HLF treatments, resulting in less weight gain, a lower carcass weight, and thinner back fat. The feed efficiency in LF treatment was higher than that of the control, but lower than that of the HLF treatment. There was no significant difference in the physical or chemical characteristics of the meat among the treatments. Thus, the heating of rice-based liquid feed had no effect on the digestibility of finishing pigs nor on the physical characteristics or chemical characteristics of the meat. With the conditions of solitary feeding and freedom restriction, the LF treatment decreased intake, growth performance, and carcass weight, but increased the feed efficiency. Thus, heating of the liquid feed improved the feed intake of pigs compared with un-heated liquid feed and significantly enhanced the feed efficiency compared with dry feed intake.