174 Forage Production and Nutritive Value of Alfalfa-bermudagrass Mixtures Managed Under Contrasting Defoliation Strategies in the Southeast US

Abstract

Incorporation of alfalfa (Medicago sativa) into bermudagrass pastures improves forage quality and decreases the reliance on synthetic nitrogen fertilizer. The objective of this study was to determine forage mass (FM), nutritive value (NV), and botanical composition of ‘Bulldog 805’ alfalfa and ‘Tifton 85’ bermudagrass (T85; Cynodon dactylon) mixtures managed under three defoliation strategies: 1) hay production (H), 2) grazing (G) or 3) dual-purpose (DP) use. The study was conducted in two locations (Headland, AL and Tifton, GA) using a randomized complete block design with two replicates. In spring 2020, grazed plots were divided in four strips and every 7-d, animals were rotated to a new strip and stocking rate was adjusted. Under DP, plots were grazed until mid-July, then forage was harvested in late August. For H plots, forage was harvested every 28 to 35-d. Forage samples were collected prior defoliation to determine FM and on grazed periods, pre- and post-grazing samples and disk meter measurements were collected. Nutritive value responses were determined using near-infrared spectroscopy. There was no effect of defoliation strategy on FM (P = 0.604; mean 3471 kg DM/ha). Greater FM (P = 0.002) was observed in July and August than June (3531 and 3976 vs 2905 kg DM ha-1, SE= 263). This response was associated with an up to 40% increase of T85 proportion in the mixture (P = 0.001). Alfalfa percentage was 78% greater for DP than G (P = 0.029). There were no differences among treatments for NV responses (P > 0.05). Among defoliation periods, crude protein, neutral detergent fiber and acid detergent fiber concentrations ranged from 14 to 22%, 45 to 58% and 28 to 35%, respectively. These preliminary results demonstrate multi-use options for this mixture in the region while aiming for increased forage nutritive value, and extended growing season, and sustainability of forage-livestock systems.

Cross-Breeding Improvement and Performance Analysis of Dominant Production Traits in Grazing-Type Alfalfa (Medicago sativa L.)

“…High-quality alfalfa should have three main characteristics, including high protein content, easy digestion and absorption, and good palatability [ 37 ]. CP is an essential nutrient for livestock, consisting of pure protein and nonprotein nitrogenous substances, which determines the ability of forage to meet animal protein requirements [ 1 ]. EE is the main raw material for caloric energy with an aromatic odor and is an important taste determinant in pastures [ 1 ].…”

“…CP is an essential nutrient for livestock, consisting of pure protein and nonprotein nitrogenous substances, which determines the ability of forage to meet animal protein requirements [ 1 ]. EE is the main raw material for caloric energy with an aromatic odor and is an important taste determinant in pastures [ 1 ]. Ash content represents the amount of inorganic mineral elements in the forage.…”

“…ADF content affects digestibility, whereas the NDF content affects taste [ 29 , 37 ]. RFV is a relatively simple index of forage quality based on ADF and NDF content and can be used to predict the intake and energy value of a forage [ 1 , 25 ]. A higher RFV of alfalfa indicates better quality.…”

“…Cultivation and development of forage alfalfa can enhance the productivity of grassland–livestock systems and achieve ecological protection [ 1 ]. Alfalfa is the most widely cultivated and utilized leguminous forage worldwide, with a large number of species and varieties [ 2 ].…”