The winter diet of dairy cows in Mediterranean climate regions is usually a total mixed ration with a base of conserved summer crops such as corn silage and alfalfa hay. However, there is increased labor and financial cost related to this kind of feeding, which could be reduced if fresh forages were used in place of some of the conserved forage in the cow diet. The objective of our study was to evaluate the effect of including fresh mixed annual ryegrass and berseem clover into the diet of dairy cows on milk, nitrogen utilization, and methane emission. Twenty-four lactating dairy cows were split into two groups and offered either a diet similar to that usually offered to the cows (CON) or one where a mixture of fresh annual ryegrass and berseem clover was used to partially substitute the corn silage and alfalfa hay in the diet (MIX). Milk yield was recorded automatically, and methane emissions were estimated using the SF₆ tracer technique. The MIX diet had lower crude protein concentration (148 vs. 170 g/kg DM) but higher DM digestibility (81.6 vs. 78.6%) than the CON diet. Compared to the cows offered the CON diet, milk yield was reduced when cows were fed the MIX diet (36.4 vs. 31.9 kg/d), but methane emissions (381 vs. 332 g/d) and nitrogen excretion were also reduced (238 vs. 180 g/d). Nitrogen use efficiency was unaffected (30.8%). In addition, milk from cows fed the MIX diet had a fatty acid profile considered to be more beneficial to human health than that of the milk from cows fed the CON diet. Increasing the protein concentration in the MIX diet, either by direct supplementation or increasing the proportion of legume in the mixed herbage, could overcome the reduction on milk and positively affect methane emission and N use efficiency.

在地中海气候区，奶牛的冬季饮食通常是总定量配比，其中以玉米青贮饲料和苜蓿干草等保守的夏季作物为基础。但是，与这种喂养有关的劳动力和财务成本增加了，如果用新鲜草料代替母牛日粮中的一些保守草料，则可以减少这种花费。我们研究的目的是评估将新鲜的一年生黑麦草和berseem三叶草纳入奶牛的饮食对牛奶，氮的利用和甲烷排放的影响。将24头泌乳奶牛分为两组，其饮食与通常提供给母牛的饮食相似（CON），或者使用新鲜的一年生黑麦草和伯西弗三叶草的混合物部分替代玉米青贮饲料和苜蓿干草在饮食中（MIX）。₆示踪技术。与CON日粮相比，MIX日粮的粗蛋白浓度较低（148 vs. 170 g / kg DM），但DM消化率较高（81.6 vs. 78.6％）。与提供CON饲粮的母牛相比，饲喂MIX饲粮的母牛的牛奶产量降低了（36.4 vs. 31.9 kg / d），但甲烷排放量（381 vs. 332 g / d）和氮排泄量也降低了（238）与180克/天）。氮的使用效率不受影响（30.8％）。另外，饲喂混合饲料的母牛的牛奶的脂肪酸谱被认为比饲喂CON饲喂的牛奶的脂肪酸对人体健康更有益。通过直接补充或增加混合牧草中豆类的比例来增加MIX日粮中的蛋白质浓度，可以克服牛奶的减少，并积极影响甲烷排放和氮的利用效率。