| Popis: |
Three experiments were conducted to assess the nutritive value of high yielding, high-Lys corn for crossbred growing-finishing pigs. Completely randomized designs were used, average initial weight of the pigs was 21 kg in each experiment (Exp.), and each treatment was replicated three times with five pigs each in Exp. 1 and 2 and with four replications of three or four pigs each in Exp. 3. The experimental periods were 104, 35, and 120 d in Exp. 1, 2, and 3, respectively. In Exp. 1, 105 pigs were allotted to seven treatments. Demand corn (DC, .31% Lys) or conventional corn (CC, .25% Lys) was used to formulate diets containing either 80, 100, or 120% of the Lys requirement for growing-finishing pigs. An additional diet contained CC on an equal-weight basis to DC in the diet that was formulated to contain 100% of the Lys requirement. As Lys level of the diets was increased, ADG, gain:feed (G:F), longissimus muscle area, percentage of muscling, and carcass weight increased (P .10) any response variable at any Lys level. In Exp. 2, 60 pigs were allotted to four treatments. Two all-corn diets containing DC or CC as the sole source of Lys were compared with control diets containing DC or CC but were formulated to contain 100% of the Lys requirement; soybean meal provided the balance of Lys in these later two diets. Daily gain, ADFI, and G:F were higher (P .10) by corn variety. In Exp. 3, 84 pigs were allotted to six treatments. Conventional corn and DC were used to formulate diets containing either 80 or 110% of the Lys requirement, plus two DC diets formulated to provide CP equal to the CP content of the CC diets. As dietary Lys increased, ADG, ADFI, and G:F increased (P .10) by corn type. These results indicate that high-Lys DC will result in growth performance and carcass characteristics equivalent to that of growing-finishing pigs fed CC in diets formulated to be equivalent in Lys. |
