Eight lactating Italian Friesian cows were housed in individual respiration chambers in a repeated Latin square design to determine their dry matter intake (DMI) and their milk and methane production, as well as to collect the total feces and urine to determine the N and energy balances. Four diets, based on the following forages (% of dry matter, DM), were tested: corn silage (CS, 49.3), alfalfa silage (AS, 26.8), wheat silage (WS, 20.0), and a typical hay-based Parmigiano Reggiano cheese production diet (PR, 25.3 of both alfalfa and Italian ryegrass hay). The greatest DMI was observed for cows fed PR (23.4 vs. 20.7 kg/d, the average of the other 3 diets). The DM digestibility was lower for PR (64.5 vs. 71.7%, the average of the other diets). The highest ash-free neutral detergent fiber digestibility values were obtained for CS (50.7%) and AS (47.4%). In the present study, no differences in milk production were observed between diets, although PR showed a higher milk yield trend. The highest milk urea N concentration (mg/dL) was found for the cows fed the WS diet (13.8), and the lowest was observed for the cows fed AS (9.24). The highest milk urea N concentration for the cows fed WS was also correlated with the highest urinary N excretion (g/d), which was found for the cows fed that same diet (189 vs. 147 on average for the other diets). The protein digestibility was higher for the cows fed the CS and WS diets (on average 68.5%) than for the cows fed AS and PR (on average 57.0%); dietary soybean inclusion was higher for CS and WS than for AS and PR. The rumen fermentation pattern was affected by the diet; the cows fed the PR diet showed a higher rumen pH and decreased propionate production than those fed CS, due to the lower nonfiber carbohydrate content and higher ash-free neutral detergent fiber content of the PR diet than the CS diet. Feeding cows with PR diet increased the acetate:propionate ratio in comparison with the CS diet (3.30 vs. 2.44 for PR and CS, respectively). Cows fed the PR diet produced a greater daily amount of methane and had a greater methane energy loss (% of digestible energy intake) than those fed the CS diet (413 vs. 378 g/d and 8.67 vs. 7.70%), but no differences were observed when methane was expressed as grams per kilogram of DMI or grams per kilogram of milk. The PR diet resulted in a smaller net energy for lactation content than the CS diet (1.36 vs. 1.70 Mcal/kg of DM for the PR and CS diets, respectively). Overall, our research suggests that a satisfactory milk production can be attained by including different high-quality forages in balanced diets without any negative effect on milk production or on the methane emissions per kilogram of milk.

在重复的拉丁方形设计中，将八头泌乳的意大利Friesian奶牛饲养在各个呼吸室中，以确定它们的干物质摄入量（DMI）及其牛奶和甲烷的产生，并收集粪便和尿液总量以确定N和能量平衡。根据以下饲草（干物质％，DM）计算了四种日粮：玉米青贮饲料（CS，49.3），苜蓿青贮饲料（AS，26.8），小麦青贮饲料（WS，20.0），以及典型的干草饲料Parmigiano Reggiano奶酪的生产饮食（PR，紫花苜蓿和意大利黑麦草干草均为25.3）。饲喂PR的母牛的DMI最高（23.4 vs. 20.7 kg / d，是其他3种日粮的平均值）。PR的DM消化率较低（64.5 vs. 71.7％，是其他饮食的平均值）。CS（50.7％）和AS（47.）获得了最高的无灰中性洗涤剂纤维消化率值。4％）。在本研究中，尽管PR显示出较高的产奶量趋势，但两种饮食之间的产奶量没有差异。饲喂WS日粮的奶牛的牛奶中尿素氮浓度最高（mg / dL）（13.8），饲喂AS日粮的牛的牛奶中尿素氮浓度最低（9.24）。饲喂WS的奶牛的最高牛奶尿素氮浓度也与饲喂相同日粮的奶牛的最高尿N排泄量（g / d）相关（其他日粮平均189对147）。饲喂CS和WS日粮的母牛的蛋白质消化率更高（平均68.5％），而饲喂AS和PR的母牛（平均57.0％）更高。CS和WS的日粮大豆夹杂物含量高于AS和PR。瘤胃的发酵方式受饮食的影响。与CS饲喂相比，PR饲喂的母牛的瘤胃pH值更高，丙酸的产生减少，这是因为PR饲喂的非纤维碳水化合物含量较低，而无灰分的中性洗涤剂纤维含量也高于CS饲喂。与CS日粮相比，以PR日粮喂养奶牛增加了乙酸盐：丙酸比率（PR和CS分别为3.30和2.44）。饲喂PR日粮的母牛比饲喂CS日粮的母牛每天产生更多的甲烷，甲烷能量损失（可消化能量摄入的百分比）更大（413 vs. 378 g / d和8.67 vs. 7.70％），但没有当甲烷表示为每千克DMI的克数或每千克牛奶的克数时，观察到差异。与CS日粮相比，PR日粮的泌乳净能量更低（PR日粮和CS日粮分别为1.36比1.70 Mcal / kg DM）。总体，