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Alfalfa Maturity and Cultivar Effects on Chemical and In Situ Estimates of Protein Degradability
Author(s) -
Griffin T. S.,
Cassida K. A.,
Hesterman O. B.,
Rust S. R.
Publication year - 1994
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1994.0011183x003400060043x
Subject(s) - cultivar , cutting , forage , biology , dry matter , agronomy , medicago sativa , lignin , neutral detergent fiber , horticulture , maturity (psychological) , chemical composition , zoology , botany , chemistry , psychology , developmental psychology , organic chemistry
The relationships among plant maturity or genotype and forage quality and ruminal in situ degradability of alfalfa ( Medicago sativa L.) are inadequately understood. A 2‐yr experiment was conducted to study the effects of cutting (spring or summer), plant maturity (six sampling dates), and cultivar (Vernal, Arrow, WL‐320, and Target II or Legend) on chemical composition and in situ degradability of alfalfa. Plant maturity was quantified by the mean stage weight (MSVO system. Herbage cell wall, cell‐wall bound N, and in situ escape protein CEP) increased significantly with MSW; crude protein (CP) and situ dry matter degradability (ISDMD) decreased. Forage nutritive quality declined less with increasing MSW in summer than in spring cuttings. In 1991, the cultivar Target II had lower ISDMD than Vernal, Arrow, or WL‐320, while summer growth of Arrow contained less EP than other cultivars. In 1992, Vernal had higher EP than Arrow, WL‐320, or Legend. High EP related to increasing maturity or cultivar differences was negatively correlated with other measures of nutritive quality. Differences in chemical composition and in situ degradability among alfaffa cultivars exist, but are dependent on growing conditions. Usefulness of the MSW system to predict alfalfa nutritive quality is limited to within cuttings, and cell‐wall bound N measures were better predictors of alfalfa EP than was MSW.