Gareth O’Keeffe

Project: Development of novel feed strategies to improve protein utilisation in forage fed ruminants

Type: PHD

Institution: IBERS

Report: The effect of red clover (Trifolium pratense L.) polyphenol oxidase on protein complexing and utilisation in forage-fed ruminants

A protein gap exists within ruminant production as a result of an inefficient relationship between feed and protein metabolism within the rumen. Ruminant production in the UK is largely dependent on grasslands approximately 52% of UK land is improved grassland and rough grazing.

Protein obtained from pasture enters the rumen and much of the available nutrients are removed and utilised by the microbial population, rather than the animal. If protein is prevented from being rapidly broken down to ammonia, which is excreted by the animal via urine, a higher proportion can continue to the small intestine to be absorbed by the animal, increasing productivity.

Previous efforts to increase protein uptake concentrated on increasing the quantity of available protein, by utilising by-pass proteins, which experienced limited success, or by increasing carbohydrates in the diet improving incorporation of protein.  Any improvement in efficiency could result in more productive farms and less environmentally damaging output.

This is important as livestock based agriculture has been under considerable strain in recent years, from a variety of internal and external factors, some of which have had deleterious effects on available feeding strategies and resources.

Improving animal feed addresses either the quality of the product, or the cost of production. Certain plants (e.g. red clover) are known to improve quality aspects of produce, but also contain the enzyme polyphenol oxidase (PPO) which could potentially protect proteins within plant matter, by either complexing with them directly or by disabling the protease enzymes that are present in the plant tissues.

PPOs are a group of enzymes present in many forage crops and may be potential candidates for improving protein utilisation in forage fed ruminants, as they have been recognised to play a role in defence mechanisms relating to coping with biotic stresses in the field alter protein properties when consumed by ruminants.

This research has been designed to answer the question; can protein complexing occur in the initially ingested plant material (down bolus) to protect plant protein?