Genetic selection for nonstructural carbohydrates and its impact on other nutritive attributes of alfalfa (Medicago sativa) forage

Abstract

AbstractHigh concentration of nonstructural carbohydrates (NSC) in forages improves ruminant N utilization and performance. The present study evaluated the direct and indirect effects of one cycle of divergent phenotypic selection for NSC in alfalfa along with the diurnal and seasonal stability of the trait. For this purpose, divergent NSC populations were developed (NSC+ and NSC−) and two field trials were established in Quebec, Canada. Forage samples were collected twice a day (morning and afternoon) and three times a year (spring, summer and autumn) and analysed for NSC, crude protein (CP), fibre concentration, digestibility and yield. The NSC+ population maintained greater NSC concentrations than the NSC− population over 2 establishment years (+18%, 129 vs. 109 g/kg) and three production years (+8%, 126 vs. 116 g/kg). Time of cutting and period of harvest had significant effects on alfalfa NSC concentration and other nutritive attributes, but they did not affect the response to selection for NSC concentration. Phenotypic selection for NSC concentration can therefore be used in a recurrent phenotypic selection approach to improve alfalfa nutritive value.