Agronomic performance and nutritional value of alfalfa (Medicago sativa L.) in ley farming: Impact of year, cultivar, and mowing time of successive cuts

This study evaluated the forage-feeding value and morpho-physiological traits of four cultivars of alfalfa (Medicago sativa L.) that were grown in a traditionally managed alfalfa ley. Seeds were planted in 2010, and data collection was in 2011 and 2012. The experimental design consisted of a split-plot with four replicates (blocks). The main factor was alfalfa cultivar (La Rocca, Miranda, Prosementi, and PR57Q53). The secondary factor was mowing time (MT), which was performed when the plants had early buds (MT1), late buds (MT2), or early flower (MT3). The experimental field was divided into three spatially distinct sectors, and each was cut three times. Each block within each sector contained the four cultivars as main plots and the three mowing times as sub-plots, resulting in 12 treatment combinations per block. There were 48 samples analyzed per cut (4 cultivars × 3 mowing times × 4 replicates). In all cultivars, the DM concentration increased as MT progressed from MT1 to MT3. The highest CP concentration was in the Miranda cultivar (191.0 g/kg DM) and the lowest was in the La Rocca cultivar (181.0 g/kg DM). The Miranda cultivar also had a lower fiber fraction. Harvesting alfalfa at the MT2 led to an acceptable trade-off in terms of yield and quality. Forage produced by the ley farming of a multifoliate cultivar of alfalfa can satisfy the nutritional requirements of dairy cows.