Forage Accumulation and Nutritive Value of Reduced Lignin and Reference Alfalfa Cultivars

Abstract

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.

Stem and leaf forage nutritive value and morphology of reduced lignin alfalfa

“…() reported an average L/S of .96 across six alfalfa cultivars grown at three locations in Minnesota. The lack of differences between reduced lignin and reference alfalfa cultivars in stem yield, leaf yield, and L/S in the present study supports recent research showing forage morphology and growth between these cultivars is similar (Getachew et al., ; Grev et al., ).…”

“…Stem and leaf NDF concentrations were comparable to reports from previous research evaluating alfalfa stem and leaf NDF concentrations across a number of cultivars and locations (Kalu & Fick, ; Lamb et al., , ; Marković et al., ; Sanderson & Wedin, ; Schnurr et al., ; Sheaffer et al., ). No prior studies have investigated NDF concentrations within stem and leaf fractions for reduced lignin alfalfa cultivars; however, total herbage NDF concentrations have been shown to be similar between reduced lignin and reference alfalfa cultivars (Getachew et al., , ; Grev et al., ).…”

“…These harvest maturity choices are determined by producer needs to optimize either herbage yield, nutritive value, or nutrient yield (Sheaffer et al., ). It has been well‐established that increasing forage maturity results in increased fiber, declined crude protein (CP), and decreased digestibility within alfalfa herbage (Brink et al., ; Grev, Wells, Samac, Martinson, & Sheaffer, ; Hall, Smiles, & Dickerson, ; Kallenbach et al., ; Lamb et al., , ). Therefore, highest herbage nutritive value and intake potential usually occur with preflowering alfalfa, while alfalfa harvested at later maturity stages has been shown to have a lower nutritive value (Brink et al., ; Kallenbach et al., ; Lamb et al., , ; Sheaffer et al., ).…”

Herbage Accumulation, Nutritive Value, and Regrowth Potential of Sunn Hemp at Different Harvest Regimens and Maturity

“…Increased NDF digestibility is associated with greater DM intake and animal production (Kendall et al, 2009). By comparison, assessed across four locations, 2 yr, and four cultivars in Minnesota, NDFD concentrations of alfalfa ranged from 278 to 453 g kg −1 (Grev et al, 2017), which was in fact lower than the NDFD values recorded for whole-plant sunn hemp in the current study. Neutral detergent fiber digestibility of different forage types can range from <25 to >75% (NRC, 2001).…”

“…This is likely because our values were derived from whole-plant analyses, whereas values derived from Mansoer et al (1997) included only leaves. However, by comparison across locations, years, and four cultivars, CP concentrations of alfalfa (Medicago sativa L.) ranged from 175 to 234 g kg −1 (Grev et al, 2017), which were within the range of CP values recorded for sunn hemp leaves (Mansoer et al, 1997). However, by comparison across locations, years, and four cultivars, CP concentrations of alfalfa (Medicago sativa L.) ranged from 175 to 234 g kg −1 (Grev et al, 2017), which were within the range of CP values recorded for sunn hemp leaves (Mansoer et al, 1997).…”