PhD: Physically effective fibre and rumen function, performance and health of UK dairy cows

Published 19 July 19

Research Partner: Harper Adams University

Start and End Date: July 2015 - June 2018

PhD Student: Usama Tayyab

It is important to feed lactating dairy cows a diet with the correct particle size distribution: when the particles are too long, they can promote diet selection and reduce milk yield; when the ration is too short, it can reduce milk fat content and possibly lead to sub-acute acidosis. Most recommendations for the optimal particle size distribution for dairy cows are based on North American diets based on lucerne haylage and/or maize silage. These may not be suitable for the wetter, grass silage based rations commonly fed in the UK.

The project is split in two parts:

  1. A survey in 50 commercial farms aiming to

    1. Evaluate and develop methods to more accurately describe forage particle size and functional fibre under UK conditions

    2. describe the range of forage particle size and functional fibre of grass and maize silages

    3. determine the influence of mixing and extent of sorting

  2. Two experimental studies aiming to

    1. evaluate how forage particle size and functional fibre affect intake, rumen function and performance

    2. examine how fibre interacts with different levels and degradability of starch

The main aim of the project is to provide recommendations to dairy farmers, nutritionists and contractors on target forage particle size to optimise rumen health and cow performance for housed cows.


The project was part of the Grassland, Forage and Soil Research Partnership with SRUC and is now complete.