Effects of Defatted Rice Bran Inclusion Level on Nutrient Digestibility and Growth Performance of Different Body Weight Pigs

Simple Summary Feed grain, including corn and soybean meal, prices, which are the company's primary raw materials, have fluctuated and escalated in recent years. Defatted rice bran, an abundant and underutilized agricultural coproduct of the paddy rice, can be used as a replacement. Additionally, nitrogen emitted as ammonia from swine manure has a negative effect on ambient air quality. This study evaluated the effects of defatted rice bran inclusion level in low-protein diets on growth performance and nutrient digestibility of different body weight pigs. Results showed that there is no difference for average daily gain for three weight stages, it meant that defatted rice bran could be used as a replacement for corns and soybean meal. Nutrient digestibility has significant difference. The study supported some theoretical foundation for the application of defatted rice bran. This study was conducted to determine the effects of low-protein diet prepared with different levels of defatted rice bran (DFRB) and weight stages on growth performance and nutrient digestibility of growing-finishing pigs. The animal experiment included three stages. A total of 240 growing pigs with an initial body weight of 28.06 +/- 8.56 kg for stage 1 were allocated to five diets including one control group and four DFRB diets supplemented with 2.5%, 5%, 7.5% and 10% DFRB, respectively. The 192 crossbred pigs with initial body weights of 55.03 +/- 7.31 kg and 74.55 +/- 9.10 kg were selected for stage 2 and stage 3, respectively. Pigs were allocated to four diets including one control group and three DFRB diets supplemented with 10%, 15% and 20% DFRB, respectively. The results showed that with the increase in DFEB intake, the gain: feed was linearly increased (p < 0.05), and the average daily feed intake tended to linearly decrease (p = 0.06) in stage 1. Except for the apparent total tract digestibility (ATTD) of acid detergent fiber (ADF) in stage 3, levels of DFRB had significant effects on the ATTD of gross energy (GE), dry matter (DM), ash, neutral detergent fiber (NDF) and ADF in three weight stages. In stage 1, with the increase in levels of DFRB, the ATTD of NDF and hemicellulose were firstly increased and then decreased (p < 0.01). In stage 2, with the increasing levels of DFRB, the ATTD of DM, ash and cellulose were firstly increased and then decreased (p < 0.01). In stage 3, the ATTD of GE, DM, ash, NDF and hemicellulose decreased linearly with the increase in levels of DFRB (p < 0.01). Collectively, DFRB could be used as a replacement for corns and soybean meal, and weight stage is important to consider when adjusting the additive proportion.