Protein fractions as influenced by cultivars, stage of maturity and cutting dates in alfalfa (Medicago sativa L.)

This study was undertaken to determine the relationship between CNCPS (Cornell Net Carbohydrate and Protein System) protein fractions and in vitro RUP (Rumen Undegradable Protein) concentration and the variability of protein fractions among alfalfa cultivars grown in Serbia. Two cultivars of alfalfa (Medicago sativa L.) - Serbian cv K 28 and American cv G + 13R + CZ were sampled at three stages of maturity. Comparing the two cultivars of alfalfa (K 28 vs. G + 13R + CZ) means, there were significant differences in all protein fractions. Two investigated alfalfa cultivars differed significantly (p< 0.01) in RUP content, cv G + 13R + CZ was higher in RUP than cv K 28. Stage of maturity had an effect on proportions of the protein fractions. From a nutritional and breeding point of view, cultivar such as G + 13R + CZ is desirable because it combine higher CP (Crude protein) values with lower protein degradability than cv K 28.