Enhancing pasture productivity with alfalfa: A review

Abstract

Alfalfa has been recognized for its superior yield and quality in seeded pastures. However, when grazing immature alfalfa there is a risk of animal losses due to frothy bloat in some ruminant livestock. Inclusion of at least 50% grass in the pasture mixture is commonly recommended to reduce the risk of bloat. Two decades of plant breeding have resulted in the release of AC Grazeland, an alfalfa cultivar that reduces the incidence of bloat. Other bloat control agents such as pluronic detergents and ionophores can also be of value. Development of grazing-tolerant alfalfa varieties is solving some of the problems associated with lack of persistence of alfalfa in mixed stands; however, they are not bloat-safe. Animal productivity commonly increases when alfalfa is included in pasture mixtures. Improvements in cattle rate of gain are observed when alfalfa contributes as little as 35% to the sward. Grazing management is the principal method for controlling pasture yield and quality as well as animal performance and bloat incidence. When grazing management is used to optimize pasture production and nutrient intake, yearling steers can gain as much as 1.5 kg head-1 d-1 and liveweight production ranging from 107 kg ha-1 (on dryland) to 1946 kg ha-1 (under irrigation) can be expected. Limiting utilization of alfalfa-based pasture to ≤70% may be more important for maximizing gain per head than managing herbage quality.