Frank B, Swensson C
Department of Agricultural Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp.
J Dairy Sci. 2002 Jul;85(7):1829-38. doi: 10.3168/jds.S0022-0302(02)74257-4.
During recent decades, efforts have been made in several countries to diminish the negative environmental influence of dairy production. The main focus has been on nitrogen and phosphorus. Modern dairy production in Western Europe is often based on imported feed-stuffs, mostly protein-rich feeds. In Sweden at least, it is wished that the use of imported feedstuffs in animal production will decrease due to the risk of contamination with Salmonella and the ban of using GMO crops in Swedish dairy production. An experiment was carried out to investigate whether a lower content of crude protein in the diet would decrease the ammonia release from cow manure and whether a well-balanced diet using only feedstuffs of Swedish origin would maintain milk production. Five treatments were arranged in a Latin square design. Two different protein supplements made of ingredients of Swedish origin were each fed at two protein levels, and a fifth imported commercial protein mix was fed at the higher level. The treatments with low protein levels (13.1 to 13.5%) had a significantly lower milk yield, kilograms of ECM, but, on the other hand the net profit, milk income minus feed cost was nearly the same in all treatments except diet C, which had lower feed cost but also lower net profit due to lower milk yield. The content of urea in milk was higher with diets high in crude protein (17%) content. A decreased protein level in the diets did not influence the content of casein or whey protein, but the commercial concentrate showed a tendency to give lower values than the Swedish mixtures. The low protein diets gave significantly lower ammonia release from manure compared with the high protein diets. There were no production differences between the diets of Swedish feeds compared with the imported control. The readily fermentable beet pulp should have helped cows use the higher N diet more efficiently and increased the response. This gives the rumen microbes a possibility to match the inflow of protein with carbohydrates. Income over feed costs shows that it is possible to compile diets using products of Swedish origin and still be competitive. On the other hand, this structure may change quickly due to altered world market prices.
近几十年来，一些国家已努力减少乳制品生产对环境的负面影响。主要关注点在于氮和磷。西欧的现代乳制品生产通常基于进口饲料，大多是富含蛋白质的饲料。至少在瑞典，由于存在沙门氏菌污染风险以及瑞典乳制品生产中禁止使用转基因作物，人们希望减少动物生产中进口饲料的使用。开展了一项实验，以研究日粮中粗蛋白含量降低是否会减少牛粪中的氨排放，以及仅使用瑞典原产饲料的均衡日粮是否能维持牛奶产量。采用拉丁方设计安排了五种处理方式。两种由瑞典原产成分制成的不同蛋白质补充剂分别以两种蛋白质水平投喂，第五种进口商业蛋白质混合物以较高水平投喂。低蛋白质水平（13.1%至13.5%）的处理方式产奶量显著较低，每千克能量校正乳产量较低，但另一方面，除日粮C外，所有处理方式的净利润（牛奶收入减去饲料成本）几乎相同，日粮C的饲料成本较低，但由于产奶量较低，净利润也较低。粗蛋白含量高（17%）的日粮会使牛奶中尿素含量更高。日粮中蛋白质水平降低并未影响酪蛋白或乳清蛋白的含量，但商业浓缩饲料的值往往低于瑞典混合物。与高蛋白质日粮相比，低蛋白质日粮使牛粪中的氨排放显著降低。与进口对照日粮相比，瑞典饲料日粮之间在生产方面没有差异。易于发酵的甜菜粕本应有助于奶牛更有效地利用高氮日粮并提高反应。这使瘤胃微生物有可能使蛋白质流入量与碳水化合物相匹配。饲料成本收益表明，使用瑞典原产产品配制日粮并保持竞争力是可能的。另一方面，由于世界市场价格变化，这种结构可能会迅速改变。
