Phosphorous reduction trials indicate production efficiencies in layer diets

Until now, despite a typical layer farm using around 7 tonnes of phosphorous during a production cycle, there has been no common approach to cutting its emissions from farms. The government’s Code of Good Agricultural Practice says farmers should avoid spreading manure, which raises soil phosphorous above target levels.

Growing awareness

The situation has been highlighted along the River Wye in Herefordshire, where citizen scientists discovered that the soil with the highest levels of phosphorous were close to intensive poultry units. Volunteers sampled 22 sites around Garren Brook, a Wye tributary, and analysed them using an Olsen phosphorous test – a standard test for phosphorous in soil. The 4 sites with the highest levels were all close to poultry farms, according to the Guardian.

Dr Rizwan Azhar, ABN poultry nutritionist, said there had been growing awareness and discussion across the industry about better phosphorous utilisation and subsequent pollution from production, particularly from layer farms.

A trial explores a reduction of 11%

Now, trial work undertaken by ABN has revealed that by implementing a novel nutritional strategy, an 11% reduction of phosphorous in the diets can be achieved without any impact on performance or egg quality.

Phosphorous is naturally bound in plant materials as phytate. This complex is not digestible by animals, so the phosphorous cannot be utilised. It is usually passed directly through the gut and is excreted.

An optimum phytase enzyme and dose

To address this, the use of synthetic enzymes called phytases is a common practice. These improve phytate degradation, increasing phosphorous availability and utilisation by the bird. Through ongoing research, ABN has identified the optimum phytase enzyme and dosage rate to maximise the breakdown of the phytate in the main dietary raw materials, increasing the phosphorous available to the birds, resulting in lower undigested phosphorous in the litter.

Azhar said: “Having reviewed our internal trial data, we have applied our learnings to a new commercial strategy to help our customers reduce their potential impact on the environment.”

The commercial trial was set up across free-range sites in the Nitrate Vulnerable Zone of the Wye Valley in Wales. Performance was recorded in terms of egg production, egg weight and quality of eggs across a total of 32,000 birds, applying this new nutritional strategy and monitoring the impact of phosphorous utilisation.

Feed intakes and body weights of the hens were recorded over the trial period, while general layer management practices were applied and monitored. The results demonstrated that ABN was able to reduce the total phosphorous delivered to the farm by 800 kg, equivalent to an 11% reduction over the production cycle. Performance was consistent throughout the laying period, and bird welfare remained good.