Feed manufacturing

Commercial fish feed production in Stokmarknes, Norway

Feed manufacturing refers to the process of producing animal feed from raw agricultural products.

Feed and types of feed

The Washington State Department of Agriculture defines feed as a mix of whole or processed grains, concentrates, and commercial feeds for all species of animals to include customer formula and labeled feeds, and pet feed (WSDA 2016). These feed are now commercially produced for the livestock, poultry, swine, and fish industries. The commercial production of feed is governed by state and national laws. For example, whole or processed grains, concentrates, and commercial feeds with the purpose of feeding wildlife and pets should be duly described in words or animation for distribution by sellers (TAC 2011). Most State and Federal codes have clearly stated that commercial feeds should not be adulterated (TAC 2011). Animal feeds have been broadly classified as (a) concentrates: Contains mainly cereal grains and their by-products and is high in energy, or maybe prepared from high-protein oil meals or cakes, and by-products resulting from sugar beets and sugarcane processing (b) roughages: Comprises of grass pastures, and plant parts like hays, silage, root crops, straw, and stover. The feed diets provided to animals are all not the same. For example, livestock animals are fed on a diet that consists mainly of roughages while poultry, swine, and fish are fed with concentrates. Occasionally, the livestock may be fed with energy feeds which usually comes from grains, supplied alone or as part of a total mixed ration.

Feed preparation and quality

The quality of the prepared feed ultimately depends on the quality of the material such as the grain or grass used. To obtained high quality feed the raw material should be of very good quality. Feed manufacturing (commercial) is an industrial process, and therefore should follow HACCP procedures. The Food and Drugs Administration (FDA) defines HACCP as “a management system in which food safety is addressed through the analysis and control of biological, chemical, and physical hazards from raw material production, procurement and handling, to manufacturing, distribution and consumption of the finished product” (FDA 2015). The FDA is the regulator of human food and animal feed for animals including poultry, livestock, swine, and fish. Additionally, FDA regulates over 177 million dogs, cats, and horses pets feed in America. Similar to human foods, animal feeds require to be unadulterated and wholesome, and be prepared under good sanitary conditions. In accordance with the FDA, the feed should properly and truthfully be labeled to provide the required information to the consumer (FDA 2014).

Feed formulation for swine

It has been reported that, “60% to 80% of the total cost of producing hogs is feed” (Rick 1995; Myer & Brendemuhl 2013). Feeds are not prepared just to provide daily stomach intake but also to enrich the animals with the requisite body nutrients for healthy growth. Formulating swine ration takes into consideration, the required nutrients for swine at various growing stages, and the required compositions of the feeds. According to Rick (1995), the basic nutrients of concern in practical swine diets are crude protein, metabolizable energy, minerals, vitamins and water. The formulation procedure of the ration has a composition that should be fixed and also a variable portion (Luce, 2013). Swine ration mostly comprises of a ground cereal grain as a carbohydrate source, a protein source mostly from soybean meal, mineral salts like calcium and phosphorus, and vitamins. The feed can be fortified with by-products of milk; meat by-products; cereal grain by-products; and specialty products. Myer and Brendemuhl (2013), discussed that antibiotics may also be added to swine feeds to fortify the feed and help improve the animal’s health growth. Rick (1995) reported of three basic methods used to formulate swine diets: Pearson square, algebraic equations and linear programs (computers). In recent times, microcomputer programs are available that will balance a diet for many nutrients and assist with economic decisions. Reports have indicated that Distillers dried grains with solubles (DDGS) is been used in place of corn and soybean meal in livestock and poultry feeds, which is rich in energy and protein (Bregendahl 2008). Corn dried distillers grains with solubles (DDGS) has become the most popular, economical, and widely available alternative feed ingredient for use in U.S. swine diets in all phases of production. The U.S. Grain Council also reported that corn DDGS is used primarily as an energy source in swine diets because it contains approximately the same amount of digestible energy (DE) and metabolizable energy (ME) as corn, although the ME content may be slightly reduced when feeding reduced-oil DDGS (U.S. Grains Council 2012).

Stein in 2007 also highlighted the recent trends in the use of DDGS, as many producers are successfully including 20% DDGS in diets of swine in all categories. Although 20% is the recommended level of inclusion, some producers are successfully using greater inclusion rates. Inclusion rate of up to 35% DDGS has successfully been used in diets fed to nursery pigs and growing finishing pigs (Stein 2007).

Feed formulation for fish

Main article: Commercial fish feed

In recent discussions, it was indicated that farmed fish are supplied with specially formulated pellet feeds containing the required nutrients to keep the fish very healthy and also to provide health benefits to humans that consume the fish. Fish can be classified depending on the feed source (animal or plant source) that they consume. Fish are broadly classified into herbivorous fish (feed source mainly of plant proteins like soy or corn, vegetable oils, minerals, and vitamins), and carnivorous fish (feed source mainly of fish oils and proteins). Carnivorous fish feeds basically contain 30-50% fish meal and oil; and recent research is suggesting the use of other alternatives to fishmeal in aquaculture diets (NOAA fisheries 2015). A fish feed should be nutritionally well-balanced and provide a good energy source for better growth. It has been reported that among the various fish feeds investigated, soybean meal was better as an alternative to fishmeal. The soybean meal to be prepared for the fish industry is heavily dependent on the flour particle sizes which mostly depict the characteristics of the feed pellets. The particle sizes have influence on feed digestibility, and the possible effect that the fish’s digestive system may experience. The particle sizes to be used to produce the fish pellet feed are influenced by grain properties and the milling process. Properties of the grain may include, its hardness, and moisture content, and properties of the milling process may include the mill equipment type used, and some properties of the mill equipment (for example corrugations, gap, speed, and energy consumption).

Feed formulation for poultry

As reports have indicated, feeding make-up the major cost in raising poultry animals as birds in general require feeding more than any other animals did particularly due to their faster growth rate and high rate of productivity. Feeding efficiency is reflected on the birds’ performance and its products. According to National Research Council (1994), poultry required at least 38% components in their feed. The ration of each feed components, although differ for each different stage of birds, must include carbohydrates, fats, proteins, minerals and vitamins. Carbohydrates which is usually supply by grains including corn, wheat, barley, etc. serve as major energy source in poultry feeds. Fats usually from tallow, lard or vegetables oil are essentially required to provide important fatty acid in poultry feed for membrane integrity and hormone synthesis. Proteins are important to supply the essential amino acids for the development of body tissues like muscles, nerves, cartilage, etc. Meals from soybean, canola, and corn gluten are the major source of plant protein in poultry diets. Supplementations of minerals are often required because grains, which is the main components of commercial feed contain very little amount of those. Calcium, phosphorus, chlorine, magnesium, potassium, and sodium are required in larger amounts by poultry. Vitamins, such as vitamin A, B, C, D, E, and K on the other hand are the component that required in lower amount by poultry animals (Chiba 2014).

Fanatico (2003) reported that the easiest and popular way to feed birds are to use pelleted feeds. Aside the convenience to the farmer, pelleted feeds enable the bird to eat more at a time. In addition to that, some researchers also found the improvement of feed conversion, decreasing feed wastage, improving palatability and destroying pathogens when birds were fed with pellet feed as compared to birds fed with mash feed (Jahan et al. 2006; Klasing 2015). Commercial manufacturing of pelleted feed usually involves series of major processes including grinding, mixing and pelleting. The produced pellets are then tested for pellet durability index (PDI) to determine its quality. To enhance good health and growth, antibiotics are often added to the pelleted feed.

Researchers have concluded that smaller particle-sized feed will improve digestion due to the increasing surface area for acid and enzyme digestion in the gastrointestinal tract (Preston et al. 2000). However, some researchers recently brought into the attention the necessity of coarse particle for poultry feed to complement the natural design and function of gastrointestinal tract (GIT). Hetland et al (2002) and Svihus et al. (2004) discussed that the GIT retention time decreased due to lack of gizzard function that eventually gave negative impact on live performance. Zanotto & Bellaver (1996), compared the performance of 21 day old broilers fed with different feed particle size; 0.716 mm and 1.196 mm. They found that the subject fed with larger particle size feed showed better performance. Parsons et al. (2006), evaluating different corn particle sizes in the broiler feed found that the largest particle size (2.242 mm) gave better feed intake than the other particle sizes tested (0.781, 0.950, 1.042 and 1.109 mm). Nir et al. (1994) however argued that the development of broiler was influenced by changing particle sizes. However variation in particle size between 0.5-1 mm usually did not have any effect on the broilers. Very fine particles (<0.5 mm) may impair the broilers performance due to presence of dust that cause respiratory problems, increase water intake, feed presence in the drinkers and increase litter moisture (Benedetti et al. 2011). Chewning et al. (2012), in their recent study concluded that although fine particle sizes (0.27 mm) enhanced broilers live performance, the pelleted feed did not.

All of these data show that both fine and coarse particle sizes do have different function in the poultry feed. Appropriate proportion of these two ingredient must be used with respect to the live performance of the broilers. Xu et al. (2013) compared the performance of non-pelleted feed to pellet with fine particles and found that the addition of coarse particle improved feed conversion and body weight. Similar results were also obtained by other researchers like Auttawong et al. (2013) and Lin et al. (2013).

Feed formulation for livestock

Livestock include beef cattle, dairy cattle, horses, goats, sheep and llamas. There is no specific requirement of feed intake for each livestock because their feed continuously varies based on the animals’ age, sex, breed, environment, etc. However basic nutrient requirement of a livestock’s feed must consist of protein, carbohydrates, vitamins and minerals (Herdt 2014). Dairy cattle need more energy in their feed than other type of cattle. Studies have shown that energy supplied by feed is provided by various carbohydrate sources include non-fiber carbohydrates (NFC) such as fermentable feeds or neutral detergent fiber (NDF) such as forage. Feeds with high NDF is good for rumen health, however provides less energy and vice versa. Fats are added in the livestock feed to increase energy concentration, especially when the NFC content is already too high since excessive NFC lessens the NDF fraction, affecting the rumen digestion. In ruminants, most proteins consumed are breakdown by microorganisms and the microorganism later get digested by the small intestine (Lalman). The N.R.C.N.R.B.C. publication (2000) suggested that the crude protein required in livestock feed should be less than 7%. Lactating ruminant especially dairy cattle require highest amount of protein, especially for milk synthesis. Minerals including calcium, phosphorus and selenium are required by livestock for maintaining growth, reproduction and bone health (Rayburn 2009).

Like other animals, livestock also require appropriate proportions of fine and coarse particles in their feed. Theoretically, finer particle will be easier to digest in the rumen, however the presence of coarse particle might increase the amount of starch into small intestine thus increasing energetic efficiency (Secrist et al.). Livestock could be fed by grazing on grasslands, integrated or non-integrated with crops production. Livestock that are grown in stalls or feedlots are landless and typically fed by processed feed containing veterinary drugs, growth hormones, feed additives, or nutraceuticals to improve production effectiveness (Silbergeld et al. 2008). Similarly, livestock are consuming grains as the main feed or as additional nutrient to the forage based feed. Processing grains for feed is aimed to get the easiest digestible grains to maximize starch availability, thus increasing the energy supply.

Hutjens (1999) reported that milk performance was significantly better when the cattle were fed with ground corn. Aldrich (Akey Inc.) compared digestibility of various corn particle size and distribution and conclude that to have 80% digestibility, particle size of 0.5 mm should be used (for 16 hr incubation) (Hutjens Dann). A research team from the University of Maryland and USDA studied the development, fermentation in rumen and starch digestion sites in lactation cow feeding on corn grain from different harvests and differently processed, and concluded that digestible, metabolizable, and heat energy were higher for high moisture corn compared to dry corn. Grinding increased DMI and resulted in increased yields of milk, protein, lactose, and solids non-fat.

Feed manufacturing process

Figure 1

Depending on the type of feed, the manufacturing process usually start with the grinding process. Figure 1 illustrates the workflow for general feed manufacturing process. Grinding of selected raw material is to produce particle sizes to be optimally and easily accepted by the animals. Depending on the formulation, feed could contain up to 10 different components including carbohydrate, protein, vitamins, minerals and additives. The feed ration can be pelleted by proportionally homogenizing the specific compositions. Pelleting could be achieved by various methods, but the most common means is using extruder machine. Hygienic environment should not be compromised during the entire process of the feed production to ensure quality feed.

Grain milling for feed preparations

Corn, sorghum, wheat and barley are the most used cereals in the preparation of feed for the livestock, poultry, swine, and fish industry. The roller and hammer mills are the two processing equipment mostly used to ground grains into smaller particle sizes (Koch 1996; Waldroup 1997). Milling the cereal grains is by mechanical action which involves several forces like compression, shearing, crushing, cutting, friction and collision. The particle size of the ground cereal is very important in the animal feed production. Smaller particle sizes increase the number of particles and the surface area per unit volume which increase access to digestive enzymes (Goodband et al. 2002). Some other benefits are increased ease of handling and easier mixing of the ingredients (Koch 1996). The average particle size is given as geometric mean diameter (GMD), expressed in mm or microns (µm) and the range of variation is described by geometric standard deviation (GSD), with a larger GSD representing lower uniformity (ASAE 1983). According to Lucas (2004), GMD and GSD are accurate descriptors of particle size distribution when the particle size distribution is expressed as log data, and are distributed log normally. Studies have shown that grinding different grains with the same mill under similar conditions would give products with different particle sizes (Nir & Ptichi 2001). The hardness of a grain sample is related to the percentage of fine particles obtained after grinding, with a higher percentage of fine particles from lower hardness grains (Carre et al. 2005). Rose et al. (2001) discussed that hard endosperm produces irregularly shaped larger particles, while soft endosperm produces smaller size particles. The correlation between particle size and energy consumed is although not positive but, to obtain very fine particle sizes require higher energy which intend reduces the rate of production. Moreover, research has shown that very fine grind of grain has no impact on the efficiency of pelleting (Martin 1985) or the power consumed during pelleting (Martin 1985; Svihus et al. 2004a). Amerah et al. (2007) discussed the availability of more data suggesting grain particle sizes are very important in mashed diets than in pelleted diets.

References

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