Changes in forage nutritive value of reduced‐lignin alfalfa during regrowth

Abstract

Genetically engineered alfalfa (Medicago sativa L.) cultivars with reduced lignin (RL) concentration are commercially available but their change in nutritive value as the crop matures within a growth cycle has not been thoroughly documented and might differ from non-RL cultivars. This research documents changes in forage nutritive value of a RL cultivar (HarvXtra-008) and two non-RL cultivars (54R02 and WL355RR) within five growth cycles across 2 yr in six states in the United States. A randomized complete block design with a split-plot arrangement of treatment randomization was used, with harvest growth cycles assigned to whole plots and cultivars to subplots in field trials. Cultivars were sampled on 3-to 4-d intervals between day 20 and 37 of regrowth. HarvXtra-008 was consistently lower (P ≤ .05) in acid detergent lignin (ADL) by 7-10% and amylase-treated neutral detergent fiber (aNDF) by 2-10% and 4-9% greater (P ≤ .05) in neutral detergent fiber digestibility (NDFD) than non-RL cultivars across all sampling dates. Cultivar × regrowth duration interactions (P ≤ .05) were found only for ADL and aNDF in two of the five growth cycles sampled, when regression coefficients were always smaller for HarvXtra-008 than 54R02. We calculated that the interval between harvests can be extended on average from 8 to 11 d for HarvXtra-008 compared with non-RL cultivars while maintaining adequate fiber digestibility for animals with high nutritional requirements; however, Abbreviations: ADL, acid detergent lignin; aNDF, amylase-treated neutral detergent fiber; CP, crude protein; MSC, mean stage count; NDFD, in vitro amylase-treated neutral detergent fiber digestibility; RL, reduced lignin; uNDF48, in vitro undigested amylase-treated neutral detergent fiber at 48 h. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Harvesting schedule effects on forage yield and nutritive values in low-lignin alfalfa

“…Grev et al [ 9 ] also reported that CP concentrations of reduced lignin alfalfa (54HVX41) were not significantly different to CP concentrations of other varieties at two of three locations in both seeding year and first production year. The improved traits of new varieties showed certain degree of advantages in CP levels [ 4 , 9 ].…”

“…Another study reported a 20 to 30% alfalfa yield increase compared 3-cut to 4-cut in a season involving the new reduced lignin variety [ 6 ]. Two studies including reduced and low-lignin varieties also found benefits of reducing the number of cuts per season [ 4 , 9 ]. There are limited data on the performance of the new variety in the first and second production year, under a fixed harvest frequency.…”

“…The tradeoff between yield and quality of alfalfa production could be changed by introducing low-lignin varieties. By reducing lignin content about 6 to 10%, the nutritive values of alfalfa can be expected to improve or maintain [ 1 – 4 ]. As a perennial legume, the performance of low-lignin varieties needs to be evaluated, specifically in the non-irrigated areas with varied weather conditions.…”

“…As a perennial legume, the performance of low-lignin varieties needs to be evaluated, specifically in the non-irrigated areas with varied weather conditions. Decreasing lignin content could bring more nutritive values for growers, however, it could alter yield, disease resistance, and morphological and physiological developments [ 4 – 7 ].…”

Alfalfa biotypes with putative enhanced cell wall digestibility and effects on performance of growing beef steers

“…Consequently, we chose d 30 of chronological age for this project, and second cutting to avoid harvest of any fall growth, to lessen the risk of grass growth in the sward, and to assure uniformity of plant re-growth initiation. Across a wide variety of alfalfa cultivars, ADL concentration is less at a 30-d, rather than 40-d, cutting interval ( Sulc et al, 2021 ).…”