Since its introduction from Eurasia, smooth bromegrass (Bromus inermis Leyss.) has become an important cool‐season forage grass in North America. The objective of this study was to document breeding progress in smooth bromegrass between 1942 and 1995 in North America. Thirty cultivars or experimental populations were tested at up to seven sites in the eastern and central USA, with a range of soil types and climates. There have been small genetic changes in forage yield, brown leafspot resistance [caused by Pyrenophora bromi (Died) Drechs.], in vitro dry matter digestibility (IVDMD), and neutral detergent fiber (NDF) concentration. Brown leafspot resistance increased gradually, averaging 0.21 units decade−1. Mean forage yield did not change for cultivars developed after 1942, but was 0.54 Mg ha−1 (7.2%) higher for the post‐1942 group than in ‘Lincoln’, a direct representative of smooth bromegrass introduced into North America. Selection for increased IVDMD led to an average increase in IVDMD of 9 g kg−1 (1.4%), an increase in forage yield of 0.33 Mg ha−1 (5.0%), and a decrease in NDF of −8 g kg−1 (−1.2%) in the post‐1942 group. The slow rate of progress for smooth bromegrass forage yield is due to its complex polyploid inheritance, emphasis on traits other than forage yield, and relatively little concentrated attention from public and private breeders.

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Switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) are important warm‐season grasses in livestock production systems in the central and eastern USA. The objectives of this study were to quantify the morphological development of ‘Trailblazer’ switchgrass and ‘Pawnee’ big bluestem and to evaluate day of the year (DOY) and growing degree day (GDD) as predictors of switchgrass and big bluestem morphological stage. Pure stands of each species were sampled at weekly intervals in 1990 and 1991 at Mead, NE, and classified as to mean stage count (MSC) and mean stage weight (MSW). Prediction equations for MSC and MSW were developed based on DOY and GDD. The validation study was harvested at 2‐wk intervals in 1992 and 1993 at Mead, NE, and Manhattan, KS, and classified as to MSC and MSW. Switchgrass and big bluestem MSC and MSW were related linearly in all environments. Linear DOY calibration equations accounted for 96% of the variation in switchgrass MSC across four environments, which indicates that switchgrass development was related to photoperiod and that general management recommendations could be based on DOY in the central Great Plains. Quadratic GDD calibration equations accounted for 83% of the variation in big bluestem MSC across four environments, which indicates that big bluestem development is more difficult to predict and management recommendations in the central Great Plains should be based on morphological development (which is best predicted by GDD). The comprehensive growth staging system gave repeatable results for quantifying the morphological development of switchgrass and big bluestem. The morphological development of switchgrass and big bluestem can be reliably predicted for adapted cultivars in the central Great Plains during years with near‐normal precipitation using DOY and GDD because of the determinate growth habit of these grasses.

The overall objective of these two studies was to evaluate the efficacy of using the proteolytic enzyme from Streptomyces griseus to estimate concentrations of ruminally degradable protein (RDP) in a wide array of forages. In the first study, alfalfa and prairie hays that previously had been evaluated in vivo for RDP were incubated in a replicated 3 x 3 factorial combination of enzyme concentrations (6.6, 0.66, and 0.066 activity units/ml of incubation medium) and incubation times (2, 4, and 48 h). Two treatment combinations (6.6 activity units for 4 h and 0.066 activity units for 48 h) yielded respective RDP estimates for alfalfa and prairie hay that were close to the known in vivo values. In the second study, 20 diverse forages were evaluated for RDP by using the in situ technique. These forages also were evaluated for RDP with the two enzyme concentrations identified in the first study, but incubation times were expanded to include 1, 2, 3, 4, and 5 h at the high concentration and 24, 30, 36, 42, 48, and 54 h at the low concentration. At the high enzyme concentration, r2 statistics from linear regressions of enzymatic estimates of RDP on corresponding estimates obtained by the in situ procedure were high (r2 > or = 0.898) at all incubation times; in addition, slopes (range = 0.88 to 1.00) and intercepts (range = -9.4 to 3.5%) approached unity and 0, respectively. At the lower enzyme concentration, r2 statistics were still good (> 0.81), but slopes (0.59 to 0.67) and intercepts (18.5 to 21.9%) for all incubation times did not meet the respective goals of unity and 0.