Changes in forage nutritive value of reduced‐lignin alfalfa during regrowth. Issue 2 (22nd December 2020)

• Record Type: Journal Article
• Authors: Sulc, R. Mark; Arnold, Angela M.; Cassida, Kimberly A.; Albrecht, Kenneth A.; Hall, Marvin H.; Min, Doohong; Xu, Xuan; Undersander, Daniel J.; van Santen, Edzard
• Is Part Of: Crop science. Volume 61:Issue 2(2021)
• Page Start: 1478
• Page End: 1487
• Publication Date: 2020-12-22
• Subjects: Crop science -- Periodicals; Cultures -- Périodiques; Cultures de plein champ -- Périodiques; Crop science; Nutzpflanzen; Zeitschrift; Pflanzenbau; Periodicals; 633
• DOI: 10.1002/csc2.20366
• Languages: English
• ISSNs: 0011-183X

Abstract

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, the extent of that longer harvest interval varied from 2 to 20 d depending on environmental conditions. Core Ideas: Genetic engineered alfalfa for reduced lignin consistently improved fiber digestibility Rate of decline in nutritive value was similar in reduced lignin and standard alfalfas Reduced lignin alfalfa enables achieving nutritive value targets at longer harvest intervals