Core Ideas Reduced lignin and reference cultivars did not differ in forage accumulation. Forage accumulation was greater with a fall harvest or a 40‐d cutting schedule. Reduced lignin alfalfa averaged 8% less acid detergent lignin and 10% greater neutral detergent fiber digestibility. Cutting treatments with shorter harvest intervals increased forage nutritive value. Delaying reduced lignin alfalfa harvest increased forage mass and maintained quality. Reduced lignin alfalfa (Medicago sativa L.) cultivars have the potential to increase the feeding value of alfalfa for livestock by improving forage fiber digestibility and to increase harvest management flexibility. The objectives were to compare the forage accumulation and nutritive value of reduced lignin and reference alfalfa cultivars when subject to diverse cutting treatments in the establishment and first production year. Research was established in 2015 at four locations in Minnesota. Reference alfalfa cultivars 54R02, DKA43–22RR, WL 355.RR, and the reduced lignin cultivar 54HVX41 were subject to cutting treatments with variable intervals between harvests. Cultivar by cutting treatment interactions were not significant (P > 0.05), but cultivar and cutting treatment effects were significant. Cultivars did not consistently differ in forage accumulation. Establishment year forage accumulation was greater when a fall harvest was taken, and first production year forage accumulation was generally greatest when alfalfa was harvested on a 40‐d cutting schedule. Compared to reference alfalfa cultivars, 54HVX41 had an average of 8% less acid detergent lignin (ADL) and 10% greater neutral detergent fiber digestibility (NDFD) but was similar in crude protein (CP) and neutral detergent fiber (NDF) concentrations. Cutting treatments with shorter harvest intervals increased forage CP and NDFD and decreased NDF and ADL concentrations. With a 5‐d harvest delay, 54HVX41 harvested on a 35‐d harvest interval had a 21% gain in forage mass and a 3% reduction in relative forage quality (RFQ) compared to reference cultivars harvested on a 30‐d harvest interval, which could allow for increased management flexibility.

Reduced lignin alfalfa (Medicago sativa L.) has the potential to improve alfalfa forage quality, yet forage morphology, biomass allocation, and stem and leaf forage nutritive value remains undetermined. The objectives of this study were to characterize changes in morphological development and forage nutritive value within stem and leaf fractions for reduced lignin alfalfa. Reduced lignin (‘54HVX41’) and reference (‘DKA43‐22RR’) alfalfa cultivars were sampled weekly from the mid‐vegetative stage through full flower during the seeding (2015) and first production (2016) year at two locations in Minnesota. Samples were staged to determine maturity, divided into stem and leaf fractions, weighed, and analyzed for forage nutritive value. Alfalfa cultivars were similar in stem and leaf yield, leaf to stem ratio (L/S), stem crude protein (CP), stem neutral detergent fiber (NDF), leaf CP, leaf NDF, leaf acid detergent lignin (ADL), and leaf NDF digestibility (NDFD). On average, reduced lignin alfalfa showed a 14% decrease in stem ADL and a 12% increase in stem NDFD compared to reference alfalfa. For both cultivars, increases in forage maturity increased stem and leaf yields and decreased L/S. Forage maturity also affected stem and leaf forage nutritive values; as maturity increased, NDF and ADL increased while CP and NDFD decreased. These results indicate that changes in forage nutritive value for reduced lignin alfalfa are largely a result of changes in ADL and NDFD within the stem fraction, and confirm that alfalfa forage nutritive value is negatively affected by forage maturity, particularly within the stem portion of the plant.

Core Ideas Teff, sudangrass, and sorghum sudangrass have potential as pasture forage for horses. Japanese and Siberian millet have little regrowth and are not ideal for pastures. Inverted Ca/P and high NO3–N were observed and should be determined prior to grazing. Annual warm‐season grasses have the potential to provide forage, but are rarely evaluated under horse (Equus caballus) grazing. The objectives were to determine yield, forage nutritive values, and preference of annual warm‐season grasses at different maturities under horse grazing. Horses grazed Japanese millet [Echinochloa esculenta (A. Braun) H. Scholz], Siberian millet (E. frumentacea L.), teff [Eragrostis tef (Zucc.) Trotter], sorghum sudangrass brown midrib (BMR) (Sorghum bicolor × S. bicolor L. var. sudanese), sudangrass [S. bicolor (L.) Moench ssp. drummondii], and annual ryegrass (Lolium multiflorum Lam.) at vegetative and mature stages in Minnesota; annual ryegrass served as a control. Sudangrass had the highest yield (P ≤ 0.01), producing ≥5.5 Mg ha−1 at the vegetative stage and ≥9.7 Mg ha−1 at the mature stage. Siberian millet produced the lowest yields at the vegetative (≤2.5 Mg ha−1) and mature (≤6.0 Mg ha−1) stages. While all grasses met the nutritional requirements of many classes of adult horses, an inverted Ca to P ratio and high nitrate‐nitrogen (NO3–N) levels were observed. Annual ryegrass was most preferred (P ≤ 0.01) with ≥60% removal at the vegetative stage and ≥40% removal at the mature stage. Siberian millet was least preferred with ≤40% removal at the vegetative stage and ≤5% removal at the mature stage. Based on maximizing yield, forage nutritive values, and preference, teff, sudangrass, and sorghum sudangrass show potential as annual warm‐season horse pasture forages; however, Ca/P and NO3–N should be determined before initiating grazing.

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Core Ideas Horses preferred winter wheat, annual ryegrass, and spring wheat. Annual ryegrass, spring oat, and winter barley were the highest yielding species. Spring oat, spring barley, and spring wheat had little to no regrowth. Winter wheat and winter rye consistently had higher forage nutritive values. Annual ryegrass can extend the grazing season or provide emergency forage for horses. Annual grasses such as oat (Avena sativa L.), wheat (Tricum aestivum L.), and barley (Hordeum vulgare L.) can serve as alternative forage but little research exists under horse (Equus caballus) grazing. The objectives were to evaluate annual cool‐season grasses for preference, yield, and forage nutritive value under horse grazing during the summer and fall in Minnesota. Spring‐planted grasses included spring barley, spring oat, spring wheat, winter wheat, and annual ryegrass (Lolium multiflorum L.). Summer‐planted grasses included the same five species plus spring forage oat, winter barley, and winter rye (Secale cereal L.). Beginning in June and September of each year, horses grazed grasses at a vegetative stage. Plots were mowed, allowed to regrow, and grazed again. Although spring oat, spring forage oat, and winter barley were often among the highest yielding grasses (≥3.0 Mg ha−1), they were also among the least preferred grasses (≤32% removal). Annual ryegrass, winter wheat, and spring wheat were among the most preferred grasses (≥35% removal). Among these highly preferred grasses, annual ryegrass was typically higher yielding (≥2.7 Mg ha−1), while winter wheat and spring wheat were among the lowest yielding species (≤4.7 Mg ha−1). All grasses contained ≥130 g kg−1 crude protein (CP), ≤610 g kg−1 neutral detergent fiber (NDF), ≤220 g kg−1 nonstructural carbohydrates (NSC), and ≥2.02 Mcal kg−1 equine digestible energy (DE). Annual ryegrass appears to be a viable forage alternative to maximize yield, preference and forage nutritive concentration in horse pastures.