Effect of the inclusion of leucaena at 100% in the native pasture area on the performance of male cattle

A drylot experiment was carried out using three grazing systems and 26 3/4 Zebu x 1/4 Holstein males with an average liveweight of 150 kg, The animals were distributed in a completely randomized design to study the inclusion of up to 100% of leucaena in the native pasture area. The systems consisted of: native pastures with 2 animals/ha, native pastures with 30% of the are a of each paddock I as leucaena with 2 animals/ha; and 100% of the area of native pastures associated with leucaena with 2 animals/ha. No fertilizatio n was applied and the animals received fresh ground sugarcane with 1% urea. during the rainy season. Blood and rumen liquor were extracted every two m onths to analyse mimosine toxicity and microorganism count. Daily gain s si gnificantly differed (P < 0.001) for the three systems and were of 425, 539 and 605 g/animal/day, respectively. Final liveweight was of 312, 357 and 3 84 kg, respectively maintaining the same daily gain pattern. Liveweight gai n/ha/year was of 310, 393 and 442, respectively being the last treatment be tter (P < 0.001) than the other two which also differed. Haematic and rumin al studies did not show toxicity disorders due to the presence of mimosine in leucaena and total bacteria and cellulolytic fungi favoured the animals fed leucaena. The inclusion of up to 100% leucaena in the system with nativ e pastures had a positive effect on daily gains and gains per hectare. Resu lts suggest; the possibility of rearing growing fattening male cattle in ar eas of native pastures associated with leucaena in 100% of the area, with s ignificant increases in liveweight gains.