Enzymes can reduce the impact of agriculture on the environment and help to preserve the quality of our living environment sustainably. When using a protease less land will be needed to raise broilers.
*By Adam Smith (DSM), Katrine Pontoppidan and Karen Margrethe Oxenbøll (Novozymes)
Environmental sustainability is a nice phrase that we hear quite often lately, yet few of us really comprehend its full meaning and importance, and even fewer are prepared to pay for it. Yet, this is a topic that aff ects all of us, not only as producers of feed or meat and eggs, but also as consumers and inhabitants of this planet.
Environmental sustainability in agriculture refers to a reduction in the impact of agriculture on the environment so that we can preserve the quality of our living environment and prolong the useful ‘lifespan’ of agricultural land and other resources. In other words, environmental sustainability is about ensuring that agricultural activities, which are for the benefi t of mankind, do not end up actually harming future generations and us. To better understand how this works, let us review what happens when protein (the second most expensive nutrient in poultry diets) is not used judiciously: undigested protein ends in manure which then reaches the broader environment. Protein in manure is rapidly converted to ammonia, nitrate and nitrous oxide, all being highly undesirable compounds. Ammonia emissions into the atmosphere cause water acidification (acid rain). Nitrate eventually leaks into the water systems causing loss of biodiversity, not to mention direct human health risks, whereas nitrous oxide, carbon dioxide and methane are important contributors of global warming. It is evident, therefore, that something as beneficial (and expensive) as feed protein can actually cause significant damage when used in excess. But, it does not have to be like that.
No increase in costs
Now, many would consider that in order to achieve a higher degree of environmental sustainability we have to actually increase the cost of poultry production, and indeed, in some cases this might be true. But coming back to protein, this is clearly not the case, and indeed, improved sustainability can be achieved while actually increasing profitability; and this is the direction being followed today by modern feed and poultry producers worldwide.
To achieve this goal, first, we must ensure that protein (amino acid) specifications are set at the right level and in the correct balance for the genetics and production capability of the animals we’re feeding. Second, we must minimise safety margins by reducing the variability in such factors that call for these margins. Third, we need to optimise protein digestibility by using highly digestible ingredients or adding an enzyme (protease) that enhances feed protein digestibility. This last solution is the current focus of activity and discussion in the research and commercial poultry sectors, worldwide. Up until recently, available proteases were part of commercial enzyme cocktails. Although any proteolytic activity was considered beneficial, it was not guaranteed, and thus, it was not taken into account during feed formulation. With the introduction of the first pure protease (under the name of Ronozyme ProAct by DSM) it is now possible to control, measure, and consider the enhanced protein digestibility conferred by the use of such a nutritional intervention strategy. Here, it should be mentioned that this particular enzyme increases amino acid digestibility of a wide range of natural feed ingredients by 3-8%. The use of this benefit to formulate lower protein diets translates into a reduction in feed cost of up to €0.02 per broiler (including the cost of the enzyme). Although this is not the focus of this discussion, it pays to stress that profitability and environmental sustainability are not mutually exclusive. In fact, not only production cost can be reduced, but also, by increasing protein digestibility we can reduce the amount of protein-rich ingredients (soybean meal being the primary source, of course) we use in poultry feed.
Less feed needed
If we were to use less soybean meal, then we would need to grow less soybeans; reduce the amount of fertilisers being produced, used, and leaked into the environment; reduce the amount of energy needed to plant, grow, harvest, transport, process and mix these soybeans into poultry feed. Considering the vast importance of poultry meat and eggs worldwide, we are talking about a huge impact by a single nutritional adjustment in poultry feed.
The fact that such enzymes are considered among the most potent tools in safeguarding our environment can be illustrated by the very fact that in the Netherlands, the use of phytase (enzyme working on phosphorus digestibility and reducing phosphate release to the environment) in poultry feed is now required by the law. It could very well be the case that in the near future such movements will be adopted by other countries (especially those with already stretched agricultural resources) and could include not only phytase but also protease, and perhaps other enzymes too. Not an unlikely scenario, considering the case of antibiotics.
A peer-reviewed paper, recently published in the International Journal of Poultry Science (2011), by Drs Oxenboll, Pontoppidan, and Fru-Nji (a joint research project by Novozymes and DSM) has looked at the environmental impact of a protease on the whole broiler production chain using Life Cycle Assessment (LCA) methodology. This LCA study has considered changes along the whole value chain, from growing feed raw materials to handling broiler manure. All results were calculated for the production of one tonne of live broilers using protease in either a normal diet or to support the use of a lowerprotein diet without any loss of performance. Performance and digestibility data were in par with expected values. The overall changes included reductions as well as increases of environmental load: reductions were from less production of feed ingredients and emission of nitrogen compounds, whereas increases related to the production of protease and the additional fertiliser needed to compensate for the lower nitrogen content of manure being applied to land as fertiliser.
Results, presented in Figure 1 and 2, show evidently that using an effective protease can significantly reduce the environmental impact of broiler production in terms of air and water systems quality. It was also demonstrated that use of Ronozyme ProAct in reduced protein diets (the typical commercial approach to use) provides a much higher environmental benefit than using the protease on top of a normal protein diet.
Major nitrogen reduction
Putting the results into perspective, we can estimate that the nitrogen content of manure can be reduced by up to 15% and ammonia emissions by up to 35% (these fi gures are in the same order of magnitude as those reported from the use of synthetic amino acids). If all broilers were fed a low protein diet and Ronozyme ProAct, then:
(a) in the European Union, from reduced ammonia emissions, the protease could contribute almost 40% of the level of reduction expected from implementation of the new animal housing regulations (28,000 versus 75,000 tonnes per annum); and
(b) in the, USA from reduced nitrogen excretion in manure, Ronozyme ProAct could deliver a reduction of 32,000 tonnes nitrogen per year, contributing significantly to the targeted 50,000 tonne reduction required by regulations.
Here, it should be stressed that results from the above study are more conservative than in other similar studies. More aggressive results indicate that the reduction of environmental impact can be even stronger. For example, in one study, acidification was reduced by triple the amount suggested by the above study, whereas in another one, the global warming impact was reduced almost five times more than in this more conservative study.
In conclusion, it is apparent that enzymes today can be used not only to improve feed digestibility and increase profitability without sacrificing animal performance, but also to enhance environmental sustainability, without actually having to pay for it.
For European producers the use of protease will result in a reduction in land area required to raise broilers. It is estimated that Europe produces about 15.9 million tonnes of broiler meat annually and the limit for organic N application is 170 kg nitrogen per hectare. When using the conservative estimation of reduced nitrogen in manure due to the use of Ronozyme ProAct in a low protein diet (-1.427 kg/tonne broilers) and adjusting this for any loss due to nitrogen volatilisation, there is a saving of 80,000 hectares. Put another way, faced with this restriction, the use of this protease in low protein diets will allow an extra 310 million 2.5 kg broiler chickens to be reared annually without the need for any extra land to dispose of the manure produced.