Sugarcane with Elephant grass replacing sugarcane with urea in the diet of crossbred dairy cows1

ABSTRACT. The objective was to evaluate the partial substitution of sugarcane treated with urea by elephant grass in the feeding of crossbred cows in lactation. Eight crossbred cows (Holstein x Gyr) were used, with 474 kg of body weight (standard deviation = 46.15 kg) and 8.15 kg of milk per day. The animals were housed in individual stalls, distributed in two 4 x 4 Latin squares, and the treatments were: sugar cane; sugar cane corrected with 0.5% of urea and ammonium sulfate (9:1); 75% of sugar cane + 25% of elephant grass and 50% of sugarcane + 50% of elephant grass, based on natural matter. In addition to the treatments, it was provided water and mineral salt ad libitum and 3 kg of concentrate supplement (24% crude protein), based on corn meal and soybean meal, supplied in two portions during the morning and afternoon milking. There was a treatment effect on the intake and digestibility of dry matter and nutrients, except for non-fibrous carbohydrate intake, and there was no effect on milk production and composition. It can be concluded that the substitution of sugarcane by elephantgrass (25 and 50%) increases the intake and decreases the digestibility of DM and OM, without affecting milk production, when the cows are supplemented with 3 kg of concentrate, containing 24% of protein per day.摘要 本研究旨在评估泌乳杂交奶牛日粮中，经尿素处理的甘蔗部分替换为象草的饲喂效果。试验选用8头荷斯坦×吉尔（Holstein × Gyr）杂交泌乳奶牛，初始体重为474 kg（标准差=46.15 kg），日均产奶量为8.15 kg。试验动物采用单栏饲养，分为2个4×4拉丁方试验设计，试验处理组如下：纯甘蔗组；经0.5%尿素与硫酸铵（质量比9:1）处理的甘蔗组；以自然物质为基础的75%甘蔗+25%象草组，以及50%甘蔗+50%象草组。除试验日粮外，自由供应饮水与矿物盐，并以玉米粉和豆粕为原料配制浓缩补充料（粗蛋白（crude protein）含量24%），每日在早、晚挤奶时分两次投喂，投喂量为3 kg/头。结果显示，试验组对干物质（dry matter, DM）及其他营养物质的采食量与消化率均存在显著影响（非纤维性碳水化合物（non-fibrous carbohydrate）采食量除外），但对产奶量及乳成分无显著影响。综上，当日粮中每日添加3 kg粗蛋白含量24%的浓缩补充料时，以25%和50%的象草替换甘蔗，可提升干物质与有机物（organic matter, OM）的采食量并降低其消化率，且不会对产奶量产生负面影响。