Evaluation of Forage Yield and Quality of Low-Lignin Alfalfa in Monoculture and Binary Mixtures in the Dark Brown Soil Zone of Saskatchewan

Non-Peer Reviewed

The objective of this study was to compare low-lignin Hi-Gest® 360 alfalfa to a conventional legume in both monoculture and binary mixtures. Two varieties of alfalfa (monoculture) [Medicago sativa L. cv. AC Grazeland (Grazeland) and Hi-Gest 360 (Hi-Gest] or in mixture (binary) with AC Success hybrid bromegrass (HB) (Grazeland+HB and Hi-Gest+HB) were grown at a Dark Brown soil zone site (52o07′ N, 106o 38′ W) in Saskatchewan and harvested at 3 maturity stages (stage) of alfalfa [1 = 10% bloom; 2 = 40% bloom; and 3 = 100% bloom)] over 2 yr. Forage was harvested on June 21, June 25, and June 29 2018, and July 8, July 12, and July 16 2019. All plots were established in a randomized complete block design with four replications using forages as treatments. Plot size was 6.2 m × 1.2 m (7.44 m²) with 4 rows and total of 48 plots. Dry matter yield (DMY; 2-yr) and nutritive value (1-yr) of forages were determined. Results indicate that monoculture Hi-Gest alfalfa had greater (P < 0.05) crude protein (CP; 19.1 vs. 17.9%, DM basis), total digestible nutrients (TDN; 68.7 vs. 66.5%), ash (11.9 vs. 11.2%), relative feed value (RFV; 186 vs. 164), sugar (5.4 vs. 4.8 %), in vitro neutral detergent fiber digestibility after a 48-h incubation (IVNDFD48: 40.7 vs. 37.6%), but lower DMY (782 vs. 1058 kg/ha), acid detergent fibre (ADF: 25.9 vs. 28.8%), neutral detergent fibre (NDF: 34.6 vs. 38.1%), compared to AC Grazeland. Forage × maturity stage interaction was not observed (P > 0.05) for forage quantity and quality. However, forages at maturity stage 3 had greater DMY (1058 vs. 783 kg), but lower CP (17.6 vs. 19.6%) and IVNDFD48 (37.1 vs. 42.3%) than those at maturity stage 1. The sugar content of forages linearly increased (P < 0.05) according to maturity stage, averaging 4.4, 4.8, and 6.2%, respectively. In terms of quantity and quality, Hi-Gest alfalfa harvested at the stage 3 was very similar with AC Grazeland harvested at the stage 2 (commercial cut) suggesting that it may be possible to delay harvest to get higher CP with the same yield as from standard alfalfa varieties cut earlier. No differences (P > 0.05) observed between AC Grazeland+HB and Hi-Gest+HB mixtures for DMY or quality profiles. Monoculture had greater CP (18.5 vs. 12.0 %), ADFCP (2.5 vs. 1.5%), lignin (6.9 vs. 4.7%), fat (3.0 vs. 2.6%), RFV (174.8 vs. 91.8), NEm (1.6 vs. 1.3 Mcal/kg), NEg (0.96 vs. 0.77 Mcal/kg), but lower DMY (920 vs. 3343 kg/ha), ADF (27.4 vs. 35.9%), NDF (36.3 vs. 61.9%), starch (0.41 vs. 0.82%), and IVNDFD48 (39.2 vs. 50.7%), compared to binary mixtures. Results suggest that Hi-Gest alfalfa as a monoculture yielded less than AC Grazeland, however Hi-Gest monoculture had higher nutritive value than AC Grazeland, but was similar for yield and quality in mixture, suggesting Hi-Gest 360 alfalfa is a viable alternative legume for Dark Brown soil zone of Saskatchewan.