|GREV, AMANDA - University Of Minnesota|
|WELLS, M. SCOTT - University Of Minnesota|
|Samac, Deborah - Debby|
|MARTINSON, KRISHONA - University Of Minnesota|
|SHEAFFER, CRAIG - University Of Minnesota|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2017
Publication Date: 11/1/2017
Citation: Grev, A.M., Wells, M., Samac, D.A., Martinson, K.L., Sheaffer, C.C. 2017. Forage accumulation and nutritive value of reduced lignin and reference alfalfa cultivars. Agronomy Journal. 109:2749-2761.
Interpretive Summary: Alfalfa is widely used as forage for livestock due to its high nutrient content. However, the lignin in the stem, which provides rigidity for stem structure, limits digestibility and utilization of alfalfa by animals. Alfalfa is harvested at an immature stage when it is most digestible, but this reduces yields and makes management of the crop more difficult. Recently, cultivars engineered for reduced amounts of lignin were released to the market, but field evaluations are needed to determine their performance under different harvest frequencies. This experiment measured yield and forage quality of a low lignin cultivar compared to conventional cultivars harvested at four stages of growth. The lower lignin cultivar had an average of 10% less lignin and 10% more fiber digestibility than conventional cultivars. The low lignin cultivar harvested on a 35-day harvest interval had a 21% gain in yield but only a 3% reduction in relative forage quality compared to conventional cultivars harvested on a 30-day harvest interval. These results indicate that the lower lignin cultivar can provide higher yields of high quality forage than conventional cultivars and provide increased management flexibility, which can reduce production costs and improve animal performance.
Technical Abstract: Reduced lignin alfalfa (Medicago sativa L.) cultivars have the potential to increase the feeding value of alfalfa for livestock by improving the forage fiber digestibility and to increase harvest management flexibility. The objectives were to compare the yield and forage nutritive value of reduced lignin and conventional alfalfa cultivars when subject to diverse cutting treatments in the seeding and first production year. Research was established in 2015 at four locations in Minnesota. Conventional alfalfa cultivars ‘54R02’, ‘DKA43-22RR’, ‘WL355RR’, 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 yield. Seeding year alfalfa yields were greater when a fall harvest was taken, and first production year alfalfa yields were generally highest when alfalfa was harvested on a 40-day cutting schedule. Compared to conventional alfalfa cultivars, ‘54HVX41’ had an average of 10% 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-day harvest delay, ‘54HVX41’ harvested on a 35-day harvest interval had a 21% gain in yield and a 3% reduction in relative forage quality (RFQ) compared to conventional cultivars harvested on a 30-day harvest interval, which could allow for increased management flexibility.