DIGESTIBILITY AND UTILIZATION OF DIETS COMPOSED OF WET DISTILLERS SOLIDS OR SOYBEAN-MEAL AND SUPPLEMENTED WITH LIQUID LYSINE PRODUCT FOR GROWING PIGS

A digestibility and balance trial was carried out to study the nutrien t digestibility and utilisation of protein and energy in wet distiller s' solids derived from barley or soyabean meal. Eight growing pigs (30 -72 kg liveweight) were used in an 8 X 6 cyclic change-over experiment al design, in which eight experimental diets were arranged 2 X 2 X 2 f actorially, The corresponding factors were the protein source (wet dis tillers' solids (DS) or soyabean meal (SBM)), protein supply (130 or 1 62 g crude protein (CP) kg(-1) dry matter (DM)) and liquid lysine prod uct supplementation. DS and SBM contained 565 g and 485 g CP kg(-1) DM , respectively, and the respective lysine contents in CP were 39 g and 64 g per 160 g N. The liquid lysine product contained 527 g CP kg(-1) DM and lysine in CP 193 g per 160 g N. No differences were found in t he total tract digestibility of the nutrients or energy among diets co mposed of DS or SBM without lysine supplementation. Those diets with l iquid lysine product supplementation, however, had opposite effects on the digestibility of the diets composed of the different protein sour ces. Lysine supplementation improved the digestibility of ash (P < 0.0 01), ether extract (P < 0.05) and crude carbohydrates (CCH) (P < 0.05) in diets composed of DS and adversely impaired the digestibility of o rganic matter and CCH (P < 0.05) in diets composed of SBM. The calcula ted digestibility of CP and gross energy were respectively 91.2% and 8 8.3% in SBM and 90.2% and 85.0% in DS, The digestible and calculated n et energy contents were respectively 18.16 MJ kg(-1) DM and 10.73 MJ k g(-1) DM for SBM and 19.31 MJ kg(-1) DM and 10.40 MJ kg(-1) DM for DS. The pigs on the diets composed of DS had higher total (P < 0.001) and urea (P < 0.01) nitrogen (N) excretion in urine and lower daily reten tion of N (P < 0.001) than the pigs on the diets composed of SBM. The liquid lysine product supplementation of the diets decreased the total and urea N excretion in urine (P < 0.001) and improved the daily N re tention (P < 0.001). With lysine supplementation, the protein utilisat ion of the diets composed of DS was improved to the level of the diets composed of SBM, No differences were observed in the utilisation of e nergy among the diets composed of different protein sources. It is con cluded that DS is highly digestible, but its protein is efficiently ut ilised only with lysine supplementation.