Average 2016 production efficiency in USA exceeded 10,000 kg milk per cow (USDA-NASS); about 5% of WI dairy herds on DHI test exceeded 13,500 kg milk per cow. Some projections suggest that average production efficiency in USA dairy herds will reach this level within 20 yr. In a survey of feeding programs from selected WI high-producing (≥13,500 kg milk per cow) herds, 63% of milk production, on average, was attributed to dietary forages. Estimated percentages of dietary nutrients provided by forages, on average, were as follows: fiber (≥75%), protein (45%), energy (50%) and starch (40%). The foregoing points denote the importance of improved forage quality. Key forage quality indicators are reduced NDF content and greater NDF digestibility (ivNDFD) for decreased fill limitation of DMI to allow for production gains from forages or the feeding of higher forage diets. In a multi-commercial lab, multi-year survey of corn silage analyses, NDF% (DM basis) and ivNDFD (30 h; % of NDF) were 41 to 36% (mean – 1 SD) and 54 to 60% (mean + 1 SD), respectively. Starch, influenced by grain yield, contributes greatly to the energy value of corn silage. In the lab survey, starch was 32 to 39% (DM basis; mean + 1 SD). The digestibility of starch in corn silage is influenced by harvest maturity, kernel processing, time in storage before feeding, and kernel endosperm properties. The ivNDFD in corn silage is influenced primarily by hybrid type and growing environment. High cutting can decrease NDF% and increase ivNDFD and starch%. Optimal chop length questions have increased in concert with the feeding of higher corn silage diets. Key forage quality indicators for legume forages also include greater CP% for reducing supplemental protein. In the lab survey, legume forage NDF, ivNDFD and CP were 42 to 37% (mean – 1 SD), 46 to 57% of NDF and 21 to 24% CP (mean + 1 SD), respectively. Reduced-lignin alfalfa varieties are now available commercially for either increased ivNDFD or extended harvest windows for increased yield. New questions involve harvest and feeding strategies when combining reduced-lignin alfalfa silage and brown midrib corn silage.