OPTIMAL BIOLOGICAL LEVELS OF DIGESTIBLE LYSINE AND THREONINE FOR GROWING PIGS

Abstract

The optimal biological levels (OBL) of digestible lysine and threonine which maximize the productive variables of growing pigs were determined, through two experiments with 100 pigs (75 castrated males and 25 females), distributed in five treatments with five repetitions and two animals per experimental unit. The evaluation consisted in five levels of digestible lysine for four weeks and five levels of digestible threonine for six weeks. To calculate the OBL of each variable, econometric models were built and solved from trends detected through orthogonal contrasts, considered for the regression analysis. The digestible lysine OBL that maximized food consumption and weight gain was 0.74% (P?0.05). The threonine OBLs for food consumption and food conversion were 0.52 and 0.55%, respectively, while for weight gain and final live weight the best response was 0.62% (P?0.05). These results indicate that the lysine and the threonine OLBs depend on the variable that needs to be optimized.