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Greenhouse gas emission
The compound feed industry is one of the stakeholders having a role in minimizing the environmental impact while meeting the demand for high quality and cost effective products. It is important to find the right balance between carbon foot print linked to the production of feed and the environmental impact linked to its consumption at the farm.
Agriculture is an important contributor to the production of greenhouse gases, which contribute to the climate change. These are carbon dioxide from energy consumption, methane from livestock and nitrous oxide from cultivated land and organic manure. According to the report Livestock’s Long Shadow (FAO, 2006), globally, livestock production is responsible for 18% of greenhouse gas emissions. From those, 13% are from extensive livestock production systems (grazing cattle, sheep and goats) and 5% from intensive livestock production systems (pork, poultry and dairy). The contribution of the various part of the production chain in an intensive system are: 56% crop contribution, 0.05% transport, 0.5-2.4% industrial processing, 42% animal production. Therefore, transport and industrial processing are far less important than crop cultivation and animal production. However, in addition to the direct emissions by the feed industrial process, the feed industry may also facilitate the reduction of emissions by the animal production through improved feed conversion rate and reduction of methane emissions.
a. Emissions by the feed industrial process:
The greenhouse gas emissions from the feed plant are almost exclusively related to the energy use. There is no standardised method or calculation or actual standard to evaluate the carbon footprint of a feed. Therefore different national feed associations are conducting collaborative studies to establish common rules to estimate the major parameters (FEFAC, 2009).
The key is the development of realistic technologies that lead to a sustainable production. A solid and prompt implementation is feasible if the technologies are coupled with an efficient use of energy, i.e. a reduced cost of production. Feed manufacturing requires power mostly for grinding and pelleting. Energy savings are an essential driver for increased competitiveness, and thus that has been a target over the years. However there are some steps requiring high energy inputs (extrusion and heat treatments) that report physiological benefits, better feed conversion, an improved feed safety and environmental impact at the farm level. Therefore, further reductions in energy consumption are limited at the manufacturing process.
Some potential areas are the specialization of plants for species; efficient transportation of raw materials by increasing the rail shipment; and shifting to locally produced raw materials.
b. Emissions by the animal:
Livestock production generates a number of emissions to the air (methane, ammonia and nitrous oxide) or to the soil (nitrate, phosphates and heavy metals). That is a key issue in certain areas with high human population and high animal density that affects the legislation and public acceptance of the livestock production. Composition of feed has a significant effect on the composition of the emissions.
Different nutritional strategies are available to reduce the emission of contaminants. Some of these strategies are already implemented in the industry because they contribute to the reduction of cost. The most important ones are:
- Use of low protein diets supplemented with synthetic aminoacids.
- Use of net energy and digestible aminoacids in feed formulation.
- Use of ideal protein.
- Feeding programs suited to productivity, breed and sex.
- Multi-stage feeding.
- Use of low levels of digestible phosphorus (P).
- Use of inorganic sources of P with high digestibility.
- Phytase supplementation.
- Use of specific additives.
Nutritional strategies are also effective to reduce the emission in the air. Reduction of ammonia in the slurry reduces the emissions. As mentioned before, low protein diets are effective to reduce N emission but also reduce aromatic components rich in sulfur (mercaptans / SH2). Acidification of urine also contributes to minimize ammonia emission to the air. Each 0.1 points of pH reduces the emission between 5 and 20%. Urine can be acidified through changes in dietary electrolyte balance or through the use of acid salts in the feed. Use of fiber and additives like prebiotics, FOS are also effective in the ammonia emission and odor problems.
Other than these specific nutritional strategies, one of the most efficient way to reduce total emissions is to increase feed efficiency. An improved feed efficiency reduces the demand for feed resources, lowers production costs and decreases the amounts of manure (N and P emissions) per animal. Feed efficiency can be improved by implementing different procedures during the feed manufacturing process:
- Pelleting of feed. Feed efficiency of a pelleted feed reduces 5% the nutrient excretion compared to a mash one.
- Minimize the waste of feed during the manufacturing, transportation, storage and distribution to the farm. The quantity of feed that is wasted on a farm can be very variable, being 5% in the best of cases. The most important critical points are: the reduction of dust generated on the farm, which can represent a direct loss of 1%; the control of the water entrance points of the tank, whether it is for cracks or for badly closed caps, or simply for condensation, which can have a devastating effect due to the growth of fungi, bacteria and the presence of mycotoxins; the correct maintenance of the distribution system and the design of the hoppers which allow an easy regulation; and a good control of rodents and birds.
- Efficient use of water on the farm to reduce the volume of manure generated.
