A Review on the Role of Exogenous Fibrolytic Enzymes in Ruminant Nutrition

Dairy production system in developing countries mainly depends on forage plants and crop residues as major portion of the Ruminants diet. The majority of the dry matter in forage crops is made up of fibre whose digestibility is limited in rumen ecosystem. Use of exogenous fibrolytic enzymes (EFE) is gaining popularity in recent days as they overcome the limitations of other methodologies which are used to improve the digestibility of fibre. Due to microbial enzyme activity, ruminants are able to break down fibrous feedstuff, but structural polysaccharides like cellulose, hemicellulose, and lignin will only be partially broken down. The primary purpose of these enzymes is to provide as many nutrients as possible from the indigestible, potentially digestible, and digestible portions of the cell wall. EFE employed in ruminant diets can be divided into three primary categories based on the specific substrates on which their enzyme activity can take place: fibrolytic, amylolytic, and proteolytic. Enzymes can be applied in liquid or granular form to hay, silage, concentrate, TMR, supplement or premix. Even though positive results were obtained, up to date animal responses to EFE supplements have varied greatly due to enzymatic handling, dosage, diet constituents, time and method of applications. This renders need for further dedicated research efforts for the broad generalization of exogenous enzyme usage in ruminant nutrition. The goal of this study was to give a concise summary of the current state of knowledge about EFE usage in ruminant diets and to discuss potential future research areas.