Pig Research Consortium champion environmentally sustainable pig production

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Local research carried out by the consortium of John Thompson and Son’s Ltd, Devenish and the Agri-Food and Biosciences Institute, investigating nutrient requirements of finisher pigs has reduced the land needed for pig slurry by 25%.

The “Going for Growth Report” produced by the Agri-Food Strategy Board sets out targets for the NI Sow Herd to grow by 40% by 2020. Producers intending to expand must still comply with environmental legislation, so careful consideration and efficient management of key nutrient inputs and outputs is ever more critical.


Phosphorus is one of those things which we can’t live with nor live without. It is essential for bone strength and growth in pigs. Unfortunately pigs are not very efficient at phosphorus digestion and absorption, hence we have to manage phosphorus nutrition very efficiently and be conscious of phosphorus excretion and the potential impact this may have on local waterways.

To answer this issue definitively the research consortium set out to establish the true phosphorus requirements of pigs. Growing and finishing pigs were offered diets formulated to contain 0.45, 0.5 or 0.6% of phosphorus. There was no effect of phosphorus level on growth performance but pigs offered diets with low phosphorus (0.45%) had weaker legs which could lead to an increase in breakages and compromise animal welfare. When the diet containing 0.5% phosphorus was offered, soluble phosphorus excretion was reduced by 50% compared to when a diet containing 0.6% was offered. These findings were adopted by the industry and as a result the soluble phosphorus being excreted to the environment has been halved. This reduction means that soluble phosphorus excretion is currently over 80 tonnes less per year than if this research had not been completed.

Work followed on phytase enzymes. This work showed that inclusion of phytase was not a simple matter of addition but many factors influence its effectiveness i.e. level of inorganic phosphorus in the diet, level of inbound organic phosphorus in the diet, form of phytase, heat stability of phytase and level of inclusion. Get any of these wrong and phosphorus excretion can increase and pig performance can be compromised.


Early work by the consortium showed that the crude protein in diets could be reduced from 21% to 19% for pigs up to 40kg. Later work took this onto finishers and successfully dropped crude protein in the later period down to 16%. What was evident in the research was the importance of amino acid balance and the importance of knowing the transfer weights of finishers. Introducing low protein finisher diets with an inadequate amino acid balance at too early a stage was found to be costly in terms of performance, nitrogen excretion and economics.

However, this work showed that getting diet formulation right in the finishing period reduced nitrogen excretion by 680g of Nitrogen/pig without compromising performance. This locally produced research data was taken to DEFRA and Brussels and resulted in the acceptance of a 25% reduction in land required for spreading pig slurry and revised Nitrates Action Plan Figures for Northern Ireland (Table 1).

Nitrogen and Phosphorus are fundamental nutrients supporting pig performance. To reduce these vital nutrients with the aim of improving the environment and not impacting on performance or welfare requires knowledge. Get it wrong and the pig, the environment and the producer’s pocket will suffer.

It is only through research that we can be confident in making changes to diet formulation in order to meet the requirement of environmental legislation. For further guidance and advice on environmental management of pig diets, please contact Devenish, Thompsons or AFBI.