Productive, marginal and economic responses of Girolando cows under grazing of Tifton 85 receiving different concentrates

ABSTRACT Energy is considered the most limiting nutrient for the production of milk cows in pastures, but will that supplementation must be energy? The objective was to evaluate the productive, marginal and economic response of Girolando cows kept in Tifton 85 pasture during rain period receiving different types of supplementation. One treatment was mineral supplementation ad libitum, a second treatment providing 1.0kg/day of protein supplementation, and a third and fourth treatments providing 2.0kg/day of protein-energetic supplementation and 4.0kg/day of energy supplementation, respectively. Twelve cows were used with average milk production 15.0±1.99kg/day. The data were evaluated as three Latin squares 4 x 4 simultaneous to the 5% level of significance. The dry matter intake of forage not influenced by supplementation (P> 0.05). The higher milk production was observed with energetic supplementation on average 14.73kg of milk/day, no different of production obtained from protein-energy supplementation, average of 13.84kg of milk/day. Marginal productive response was observed, with responses of 1.03; 0.84 and 0.44kg milk/kg concentrate for proteic supplement, proteic-energetic, and energetic, respectively. Positive financial balance was found for protein and protein-energy supplements in relation to mineral supplementation. Protein-energy supplementation proved the most efficient.

摘要：能量被认为是牧场泌乳奶牛生产中最受限制的营养物质，但此类补饲是否必须以能量为核心？本研究旨在评估雨季期间饲养于提夫顿85号饲草（Tifton 85）牧场的吉兰朵奶牛（Girolando）在接受不同类型补饲时的生产性能、边际效益与经济响应。试验共设置4个处理组：其一为自由采食矿物质补饲组；其二为每日补饲1.0kg蛋白质补充料组；其三与其四分别为每日补饲2.0kg蛋白能量补充料组与4.0kg能量补充料组。试验选用12头泌乳奶牛，初始平均日产奶量为15.0±1.99kg。本研究采用3个4×4拉丁方设计对数据进行统计分析，显著性水平设定为5%。饲草干物质采食量不受补饲措施影响（P>0.05）。能量补充料组的平均日产奶量最高，达14.73kg，其生产性能与蛋白能量补充料组无显著差异，后者平均日产奶量为13.84kg。各组边际生产响应分别为：蛋白质补饲组、蛋白能量补饲组与能量补饲组每千克浓缩料对应的产奶增量依次为1.03kg、0.84kg与0.44kg。与矿物质补饲组相比，蛋白质补饲组与蛋白能量补饲组均获得了正向经济收益。其中蛋白能量补饲组被证实为最优补饲方案。