This study aimed to identify individual characteristics differing among high-efficiency (HE; upper 20%, n = 31), low-efficiency (LE; lower 20%, n = 31), and mid-efficiency (ME, 60% n = 93) lactating cows. Primiparous (37) and multiparous (118) high-producing milking cows at 30 to 180 d in milk were fed individually a low-roughage diet [31.6% of dry matter (DM)] for 4 wk. Daily average DM intake, rate of eating, visit duration, meal size, and daily rumination time were higher in LE compared with HE cows. On the other hand, HE cows exhibited higher digestibility of DM, crude protein, and neutral detergent fiber than the LE cows. Daily eating time was similar in the HE and LE groups and higher than that of the ME cows. Visit and meal frequency, average visit and meal duration, daily lying time, and pedometer activity were similar in the HE, LE, and ME groups. The HE cows produced 1.75% more milk, but similar energy-corrected milk compared with the LE cows. Milk fat and protein content were lower by 1.8 and 3.8%, respectively, in the HE cows than in the LE group. Body weight (BW) and BW gain were similar in the 3 efficiency groups. Diurnal distribution of DM intake showed 6 distinct major meals, each composed of 1.1 to 1.6 visits. Higher intake peaks (greater meal size) were found in the LE cows compared with the HE group. Daily DM intake was highly correlated (affected) with energy-corrected milk production (r = 0.61), BW (r = 0.4), eating rate (r = 0.57), and visit size (r = 0.54). Energy balance showed that the lower efficiency of the LE cows was attributed to their excess heat production and energy loss.

这项研究旨在确定高效率（HE;较高的20％，n = 31），低效率（LE;较低的20％，n = 31）和中等效率（ME，60％n = 93）泌乳的母牛。在牛奶中30到180天时，将初产（37）和多胎（118）高产挤奶牛分别饲喂低粗饲料[31.6％干物质（DM）] 4周。与HE母牛相比，LE的每日平均DM摄入量，进食率，探访时间，进餐量和每日反刍时间要高。另一方面，HE奶牛比DM奶牛表现出更高的DM，粗蛋白和中性洗涤剂纤维的消化率。HE组和LE组的每日进食时间相似，高于ME组。HE，LE，和ME组。与LE奶牛相比，HE奶牛的产奶量增加了1.75％，但经过能量校正后的奶量相似。与LE组相比，HE母牛的乳脂和蛋白质含量分别降低了1.8％和3.8％。3个效率组的体重（BW）和体重增加相似。DM摄入量的昼夜分布显示有6种不同的大餐，每餐包含1.1到1.6次就诊。与HE组相比，LE奶牛的摄入量峰值更高（进食量更大）。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。但与LE奶牛相比，类似的能量校正牛奶。与LE组相比，HE母牛的乳脂和蛋白质含量分别降低了1.8％和3.8％。3个效率组的体重（BW）和体重增加相似。DM摄入量的昼夜分布显示有6种不同的大餐，每餐包含1.1到1.6次就诊。与HE组相比，LE奶牛的摄入量峰值更高（进食量更大）。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。但与LE奶牛相比，类似的能量校正牛奶。与LE组相比，HE母牛的乳脂和蛋白质含量分别降低了1.8％和3.8％。3个效率组的体重（BW）和体重增加相似。DM摄入量的昼夜分布显示有6种不同的主餐，每餐包括1.1到1.6次就诊。与HE组相比，LE奶牛的摄入量峰值更高（进食量更大）。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。3个效率组的体重（BW）和体重增加相似。DM摄入量的昼夜分布显示有6种不同的大餐，每餐包含1.1到1.6次就诊。与HE组相比，LE奶牛的摄入量峰值更高（进食量更大）。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。3个效率组的体重（BW）和体重增加相似。DM摄入量的昼夜分布显示有6种不同的大餐，每餐包含1.1到1.6次就诊。与HE组相比，LE奶牛的摄入量峰值更高（进食量更大）。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。每日DM摄入量与能量校正后的产奶量（r = 0.61），BW（r = 0.4），进食率（r = 0.57）和就诊量（r = 0.54）高度相关（受影响）。能量平衡表明，LE奶牛的效率较低归因于它们过多的热量产生和能量损失。