Rancid Rice Bran Affects Growth Performance and Pork Quality in Finishing Pigs

Two experiments were conducted to evaluate the feeding value of rancid rice bran in finishing pigs. In exp. 1, fresh (FRB), rancid (RRB), pelleted and extruded rice bran were used to determine stability and nutrient digestibility. The free fatty acid (FFA) values of FRB and RRB were 8.2 and 15.3%, respectively. Some of the FRB was pelleted (70°C) or extruded (110°C). In exp. 2, a total of 48 pigs (Landrace×Yorkshire×Duroc, 51.12±0.5 kg) were employed for a 56-d feeding trial with 3 treatments: Control (defatted rice bran+animal fat), 20% FRB (8.2% FFA), and 20% RRB (15.6% FFA). There was a significant difference (p<0.05) in FFA% between raw and pelleted, and extruded rice bran on d 10 after storage. On d 30 the extruded rice bran showed lower (p<0.05) FFA% than the pelleted one. Dry matter digestibility was higher (p<0.05) in processed rice brans (pelleted or extruded) than raw rice bran (FRB or RRB). Energy and protein digestibilities in extruded rice bran were higher (p<0.05) than those in raw rice brans. The digestibilities of isoleucine, leucine and phenylalanine were lower (p<0.05) in RRB than FRB. Pigs fed diets containing FRB grew faster (p<0.05) and showed better feed conversion ratio (p<0.05) than those fed diets containing defatted rice bran or RRB. Carcass characteristics including dressing percentage and backfat thickness were not affected (p>0.05) by dietary treatments. With increasing storage time, the raw pork from RRB showed higher (p<0.05) thiobarbituric acid reactive substance (TBARS) and peroxide value (POV) than those from FRB when stored at 1°C for 3 weeks. Cooked pork showed rapid increase in TBARS and POV as compared to raw pork regardless of rice bran rancidity. As the storage time passed, Lightness (L) was lower (p<0.05) in RRB than FRB. Redness (a) was higher (p<0.05) in control than rice bran groups when stored 2-3 weeks. However, there was no difference (p>0.05) in redness (a) between the two rice bran groups. In conclusion, feeding rancid rice bran gave negative effects on growth performance and pork quality in finishing pigs. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 1 : 94-101)