In dairy farming systems, growing winter crops for forage is frequently limited to annual grasses grown in monoculture. The objectives of this study were to determine how cropping grasses alone or in mixtures with legumes affects the yield, nutritional composition, and in vitro digestibility of fresh and ensiled winter crops and the yield, nutritional composition, and in vitro digestibility of the subsequent summer crops. Experimental plots were planted with 15 different winter crops at 3 locations in Virginia. At each site, 4 plots of each treatment were planted in a randomized complete block design. The 15 treatments included 5 winter annual grasses (barley [BA], ryegrass [RG], rye [RY], triticale [TR], and wheat [WT]) in monoculture (i.e., no legumes [NO]) or with 1 of 2 winter annual legumes (crimson clover [CC] and hairy vetch [HV]). After harvesting the winter crops, corn and forage sorghum were planted within the same plots perpendicular to the winter crop plantings. The nutritional composition and the in vitro digestibility of winter and summer crops were determined for fresh and ensiled samples. Growing grasses in mixtures with CC increased forage dry matter (DM) yield (2.84 Mg/ha), but the yield of mixtures with HV (2.47 Mg/ha) was similar to that of grasses grown in monoculture (2.40 Mg/ha). Growing grasses in mixtures with legumes increased the crude protein concentration of the fresh forage from 13.0% to 15.5% for CC and to 17.3% for HV. For neutral detergent fiber (NDF) concentrations, the interaction between grasses and legumes was significant for both fresh and ensiled forages. Growing BA, RY, and TR in mixtures with legumes decreased NDF concentrations, whereas growing RG and WT with legumes did not affect the NDF concentrations of either the fresh or the ensiled forages. Growing grasses in mixtures with legumes decreased the concentration of sugars of fresh forages relative to grasses grown in monoculture. Primarily, this decrease can be attributed to low concentrations of sugars of mixtures with HV (10.5%). Growing grasses in mixtures with legumes reduced the fiber digestibility of both winter crops (75.7% to 72.8% NDF). Growing grasses in mixtures with legumes did not affect estimated DM yield, nutritional composition, or digestibility of the succeeding summer crops. In conclusion, growing grasses in mixtures with legumes as winter forage crops can increase forage estimated DM yields and its nutritional quality in dairy farming sytems.

在奶牛养殖系统中，冬季生长的草料通常仅限于单种种植的一年生禾草。这项研究的目的是确定单独种植或与豆科​​植物混合种植草如何影响新鲜和青贮冬季作物的产量，营养成分和体外消化率，以及随后的夏季作物的产量，营养成分和体外消化率。实验地块在弗吉尼亚州的3个地点种植了15种不同的冬季作物。在每个位置，将每种处理的4个地块种植在随机完整块设计中。这15种处理方式包括采用单一栽培的5种冬季一年生禾草（大麦[BA]，黑麦草[RG]，黑麦[RY]，小黑麦[TR]和小麦[WT]）或单种种植中有1种2个冬季一年生豆科植物（深红三叶草[CC]和多毛etch子[HV]）。收获冬季作物后，在垂直于冬季作物播种的同一地块内种植了玉米和饲料高粱。确定新鲜和青贮样品的冬季和夏季作物的营养成分和体外消化率。在含有CC的混合物中种植草可以提高牧草干物质（DM）产量（2.84 Mg / ha），但具有HV的混合物的产量（2.47 Mg / ha）与单一栽培的草的产量（2.40 Mg / ha）相似。将草与豆类混合种植后，新鲜草料的粗蛋白浓度从CC的13.0％增至15.5％，而HV的17.3％增至17.3％。对于中性洗涤剂纤维（NDF）浓度，新鲜饲料和青贮饲料的草和豆类之间的相互作用非常重要。在与豆类混合物中生长BA，RY和TR会降低NDF浓度，RG和WT与豆类一起生长不会影响新鲜或青贮饲料的NDF浓度。与单一种植的草相比，在与豆类混合的草中种植草降低了新鲜草料中糖的浓度。首先，这种下降可归因于与HV（10.5％）的混合物中糖的低浓度。与豆科植物混合种植草会降低两种冬季作物的纤维消化率（NDF分别为75.7％至72.8％）。在与豆类混合的作物中种植草，不会影响估计的后续DM作物的DM产量，营养成分或消化率。总之，与豆科植物混合的草种作为冬季饲料作物可以提高估计的牧草DM产量及其在奶牛养殖系统中的营养质量。