Published Thursday, 28th April 2022

Looking to reduce agricultural emissions? Feed additives should be part of your plans

Super dosing enzymes

In recent years we have seen increasing interest from consumers in relation to the way their food is produced. This is, in turn, influencing the behaviour of the animal production and feed industry.

Originally the pressure was basically a request for improved animal welfare. More recently the environmental impact of food production has become more of a focus for consumers. The animal industry, and nutritionists specifically, should therefore be looking at how to improve animal production not only from a performance perspective but also considering these extra parameters.

The most used environmental impact metric has traditionally been to calculate the emissions back to CO2 equivalent (CO2e) using an accredited model based on IPCC standards. This is a clearly defined method where different emissions are corrected based on their pollutant factors to produce one single value.

How does the emissions model work in practice?

When assessing the emission of broiler production using an IPCC standard, we have observed that feed formulation represents around 75% of the emissions. This reinforces the key role nutritionists can play in reducing emissions from feed and consequently from broiler production.

As improvements in performance have always been part of the responsibility of nutritionists when formulating diets, this statement can be oversimplified. It would seem reasonable to assume animals with better performance would logically obtain the target weight consuming less feed and consequently have lower environmental impact. But the fact is that animals with similar performance and costing can have wide differences in CO2e/kg of meat. Therefore, environmental impact needs to be seen beyond simple performance and cost benefits, and instead be about improving the use of the nutrients present in the diet.

When you use the model to compare different feed treatments any effect on CO2e is calculated from the combination of changes in feed composition and animal performance. As an example, a lower protein diet with less soybean meal inclusion most likely has a lower amount of CO2e per tonne of feed, but if the animal performance is not as good then the CO2e per kg of broiler produced may not be reduced. However, if equivalent performance can be achieved then the CO2e per kg of broiler produced will be lower. At the same time, it is also likely that the diet cost has reduced, giving a win-win situation.

What impact can enzymes have on the sustainability of broiler production?

The use of enzymes in feed formulation has long been recognised as a way to reduce environmental impact, improve animal performance and reduce feed cost. However, most of this benefit came through an over the top, or minimal use, of matrix values.

Utilising the full matrix for enzymes typically results in lower levels of soybean meal in the diet and thus the environmental footprint of broiler production can be substantially reduced, provided animal performance is equivalent. However, most nutritionists are reluctant to use the full matrix values supplied by additive suppliers, often applying substantial ‘safety’ margins. Additionally, while a matrix value for one additive may be 100% correct, it doesn’t mean that one could apply such a matrix in diets where more than one additive is in use: The additive matrix values are not additive!

This is because the first additive in use improves nutrient utilisation, which then leaves less room for improvement for the second additive and so on. A typical approach to this dilemma is to use 80% of the combined matrix values of a combination of additives, for instance when calculating with both phytase and xylanase in a diet.

Today, phytases and carbohydrases are widely accepted in poultry nutrition but, despite this, the way in which feed enzymes are applied to diets remains conservative. Historically, this has been based on a limited understanding of the level and nutritional influences of enzyme substrates and of the changes enzymes can bring about to animal metabolism and physiology.

How do we maximise the potential of feed enzyme application?

In recent times our understanding in each of these areas has progressed, opening up new opportunities to exploit the full potential of feed enzyme application. The concept of using the full recommended nutrient release values like this has been called Maximum Matrix Nutrition or MMN.

This strategy capitalises on the properties of Quantum Blue, an enhanced E. coli phytase with a high affinity for phytate resulting in maximum reduction of the negative effects of phytate. Combining this with a stimbiotic product containing a thermostable and inhibitor-resistant xylanase as well as fermentable xylo-oligosaccharides (Signis) enables customers to take higher dietary nutrient contributions whilst maintaining animal performance, enabling considerable cost savings and a reduction in the excretion of nutrients.

Is there evidence to support the use of targeted enzyme application?

Extensive research has been conducted to determine the effect of targeted enzyme application to degrade both phytate and NSP, reducing the antinutritive effects of both substrates. These risks can be mitigated in a precision enzyme combination strategy which delivers complete phytate breakdown whilst reducing viscosity and increasing fibre fermentability. Lee et al. (2018) and Aftab & Bedford (2018) published two studies demonstrating that there are important systemic effects when using higher doses of phytase and xylanase, aiming a strong action on both substrates (phytate and NSP), reducing the deleterious effects of these antinutritional factors, resulting in a great cost saving opportunity of formulation with maintenance of zootechnical performance

At the European Symposium on Poultry Nutrition in Gdansk in 2019 a trial was presented to test whether this approach is valid. In this broiler trial a control diet (PC) was formulated to normal nutrient levels utilising the expected nutrient release of a standard 500 FTU/kg dose of phytase (Quantum Blue).

A second diet was formulated to contain 1500 FTU/kg of phytase as well as a stimbiotic product (xylanase (9600 BXU/kg) combined with fermentable xylo-oligosaccharides (Signis)). For this diet (MMN) the calculated nutrient release of the combined package was slightly higher than the normally recommended levels to ensure the outcome would be valid even considering safety margins.

Benefits of combined matrix values

The MMN diet was substantially lower in monocalcium phosphate, soybean meal and fat (soy oil) due to the implementation of the combined matrix values. There was also a substantial cost reduction, although of course the actual cost reduction will very much depend on market conditions.

The results show that performance for the two groups was very similar, with no differences in weight gain, feed intake or feed conversion. But calculation of the CO2e showed a clear difference in favour of the MMN group. There was a 3.6% reduction in CO2e which was statistically significant.

Another way to look at efficiency is to calculate the amount of phosphorus (P) or protein (as indicated by lysine) is needed to produce each broiler. This data clearly shows a substantial reduction (12% less P and 3% less lysine) in the resources needed to produce broiler chicken.

The data shows that if feed additives such as enzymes are used whilst taking nutrient release values into account it is possible to achieve significant reductions in CO2e figures at the same time as lower feed cost and maintaining animal performance.

Where do I start in reducing emissions?

The first stage in reducing emissions is to ensure you understand the current situation by measuring your current levels. This will allow you to plan and take the appropriate actions, including the optimal use of feed additives, to reduce environmental impact of your operation.

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