Amino acid and energy digestibility in different sources of rice bran for growing pigs

Abstract

Studies were carried out to determine the digestibilities of amino acids (AA) and energy in five sources of rice bran (RB). The sources of RB included two that were not further processed, a defatted, an extruded, and an atypical source of RB consisting mainly of starchy endosperm referred to as polish. Six barrows, average initial body weight 36.5 kg, were fitted with a simple T-cannula at the distal ileum, and fed six diets according to a 6 × 6 Latin square design. The five RB-containing diets contained 53.8% corn, 19.9% soybean meal, and 23.1% RB. The basal diet contained 71.0% corn and 26.3% soybean meal. The dietary allowance was provided at a rate of 4% (wt/wt) of the individual body weight determined at the initiation of each experimental period. Each experimental period comprised 11 d. Following a 7-d adaptation period, faeces were collected for 48 h and ileal digesta for 24 h in two 12-h periods. Chromic oxide was used as the digestibility marker. There was considerable variation in AA digestibilities among the RB samples. By aid of the difference method under the dietary conditions specified, the apparent ileal digestibilities of lysine, methionine, threonine, and tryptophan ranged from 62.6 to 82.2, 61.4 to 76.0, 58.4 to 82.8, and 58.8 to 82.6%, respectively. The digestibilities were lowest in the defatted source of RB and highest in polish. Not including polish of which the total tract energy digestibility was 88.2%, the digestibilities of the other samples ranged from 60.5 to 65.8%. A small proportion of the variation in AA digestibility can be attributed to the content of crude protein, fat and ash in RB. Key words: Amino acids, digestibility, energy, pigs, rice bran