Nutritive Value and Forage Yield of Alfalfa Synthetics under Three Harvest-Management Systems
- D. L. Vaughn,
- D. R. Viands and
- C. C. Lowe
Sequential selection for agronomic vigor, high crude protein (CP) concentration, and low acid detergent fiber (ADF) concentration has been proven to increase forage quality of alfalfa (Medicago spp.) when subjected to the harvest schedule (three harvests at 6-wk intervals, beginning late May) recommended for most of New York. No research has been reported to indicate that forage quality and yield of alfalfa populations bred for improved forage quality are also improved under other harvest systems. The objective of this research was to compare three forage quality-improved alfalfa synthetics to ‘Saranac AR’ and ‘Oneida VR’ for nutritive value and forage yield under three harvest-management systems typically used in the northeastern USA. Field experiments were conducted at two locations for two production years. Soil types were Rhinebeck silt loam (fine, illitic, mesic Aeric Ochraqualt) and Williamson silt loam (coarse-silty, mixed, mesic Typic Fragiochrept). The management systems, each based on three harvests per year, varied in date of initial harvest (recommended first harvest date vs. a 10-d delay) and in regrowth interval (5 vs. 6 wk between Harvests 1 and 2). The quality-improved synthetics averaged 2 and 6% lower forage yield in 1985 and 1986, respectively. The synthetics developed partly from exotic germplasm had the lowest yields. Within years, locations, and harvest systems, the quality-improved synthetics were nearly always better than the standard cultivars in all measured quality components. The improved synthetics averaged 16 and 13 g kg-1 lower neutral detergent fiber (NDF) and ADF, respectively, compared to the standard cultivars. The improved synthetics averaged 16, 17, 12, and 3 g kg-1 higher true digestibility (TD), cell wall digestibility (CWD), CP, and cell wall protein (CWP) concentrations, respectively. Therefore, plants selected for higher nutritive value under a recommended harvest sequence can be developed into synthetics with improved quality when grown under other typical harvest systems.
Copyright © 1990.