Factors Influencing Protein Utilisation in Legume Silage and Hay for Ruminants

Abstract

Forage legumes are a vital source of sustainable, cost-effective protein sources for ruminants, but maintaining their protein quality is challenging. Preserved legumes with high protease activity and no anti-proteolytic mechanisms, like alfalfa, are prone to protein degradation, reducing nitrogen utilisation efficiency. Proteolysis by plant proteases begins post-mowing and decreases as forage dry matter increases during wilting. Optimal ensiling at 35%–55% DM minimises secondary fermentation and protein degradation. In legume hay production, extensive crude protein losses occur due to leaf shattering if the forage is baled above 85% DM. At below 80%–84% DM, aerobic spoilage decreases hay digestible crude protein. Effective legume hay preservatives include organic acids with or without buffering. For legume silage, homofermentative lactic acid bacteria and organic acids effectively decrease losses due to undesirable plant activity and secondary fermentation. High protein degradation during ensiling reduces nitrogen utilisation efficiency, leading to nitrogen pollution and adverse effects on reproductive performance and health from excess rumen-degradable protein and biogenic amine production. Legume forages significantly impact animal production profitability, but the degree to which they do so is dependent on the quality of preserved protein. Proper harvesting and storage protocols are crucial for hay and silage production, with preservatives complementing efforts to preserve standing forage protein quality effectively.