Vegetable oils in the feed compound production

28 January 2020

The most important role in the intensification of animal farming, ensuring higher sustainable rates of manufacture of food products of animal origin, is played by rationed, balanced and complete feeding of animals.

The nutritional value and type of food affect the growth rate of animals, the formation of muscle tissue, the mass of internal organs, the concentration of hormones, the parameters of protein and lipid metabolism, and the composition of fatty acids in fat.

In the nutrition of farm animals, proteins, carbohydrates, fiber, chlorophylls, carotenoids, phosphatides, tocopherols, sterols, vitamins, trace elements and fats are of great importance as a source of energy and essential fatty acids.

The lack of these components leads to growth retardation, impairment of reproductive functions, decreased productivity and deterioration in product quality, etc. At intensive industrial fattening of livestock and poultry, it is necessary to introduce fats and proteins, trace elements, vitamins into the rations of animals at certain moments.

The oil and fat industry is a potential source of manufacture of high-quality feed products for various types of animal farming, since the composition of oil-containing raw materials includes all the necessary components for animal nutrition.

In the process of manufacture of fat and oil products at various stages, in addition to oil, cake or meal, numerous by-products and waste are formed, which have a high feed value. These include deodorization cuts, phosphatides, calcium salts of fatty acids and some wastes - soap stocks of light oils, refining fatty decoloring clays.

The cakes and meals obtained during the vegetable oils production are high-protein products containing, depending on the processed culture, from 20 to 40% of protein, up to 15% of vegetable oil and a number of biologically active substances (tocopherols, sterols, carotenoids, phospholipids).

The feed value of the obtained cake and meal depends not only on the type of the processed crop, but also on the technological schemes for the oils extraction. The content and quality of the protein in the cake or meal is influenced by the preparatory operations for dehulling the seeds and separating the husk, the achieved level of oil recovery and the quality of the unrecovered oil.

The high-protein sources in the feed production can be cakes and meals obtained from oil-containing seeds of sunflower, soybeans, rapeseed. Watermelon and pumpkin seeds, which have high content of omega-3 acids, can serve as unconventional sources of compound feed.

Since in the process of oil extraction, a part of the vegetable oil remains in the cake (up to 15%) and meal (up to 1.5%), the quality of the oil remaining in it, the state of the protein and, first of all, the degree of its denaturation are of great importance.

In recent years, the introduction of vegetable oils directly into animal feed has been widely used to enrich feed with polyunsaturated fatty acids.

Vegetable seed oils are distinguished by a high content of mono- and polyunsaturated fatty acids (up to 80%), which are easily oxidized by atmospheric oxygen to form various products, some of which bind to protein, which have a physiologically unfavorable effect.

Earlier, when fattening pigs, for the enrichment of meat with polyunsaturated fatty acids, a mixture consisting of barley and triticale, the lipid part of which is rich in linoleic acid, was used in the feed composition. When using such a feed, the level of linoleic acid (ω = 6) in meat increased and, at the same time, the content of acids ω = 3 fell.

Enrichment of pigs ration with unsaturated fatty acids w = 3 and w = 6 by feed enriched with polyunsaturated lipids, including through the introduction of vegetable oils, is favorable, as it increases the dietary properties of pork.

However, excessive levels of unsaturated fatty acids can reduce the oxidative stability of pork fat, which will affect the organoleptic and sensory properties of the meat and reduce its shelf life.

Pork meat is rich in iron and cholesterol. It reduces the stability to lipid oxidation.

The oxidation of cholesterol can proceed according to the scheme of fatty acid oxidation. It is assumed that the formation of hydroperoxides during lipid oxidation is required during the cholesterol oxidation.

The high level of PUFAs in feed phospholipids and the fact that they are not protected from the action of oxygen in cells and near cell membranes can also cause lipid oxidation within cells. It is assumed that lipid oxidation may also be the cause of lipid oxidation within cells.

It is known that fats and oils can very easily undergo the oxidation by atmospheric oxygen due to the presence of fatty acids in their composition, which have one or more unsaturated bonds in their structure.

The oxidation of oils with atmospheric oxygen is a complex chain process consisting of several stages: period of initiation, induction, exponential and chain termination. The oxidation rate, along with the degree of the oil unsaturation, is influenced by the temperature, the presence of oxygen, prooxidants - metals of variable valence (copper, iron, etc.), antioxidants.

When oils are oxidized, the resulting oxidation products can react with each other and with other protein components.

Lipid hydroperoxides formed during oxidation easily react with free amino groups of amino acids of proteins. So, when reacting with a-amino acids, ammonia, carbon and a molecule of dialdehyde are formed, which turns into brown pigments in the process of secondary reactions. The reaction products of lipid hydroperoxide with a protein molecule are tightly bound to the protein.

Another very active oxidation product is the aldehyde group. At a contact with a protein or a free amino acid, it forms the so-called Schiff bases, which react with another aldehyde molecule and, when this reaction takes place several times, the product becomes darker.

The interactions between oxidized lipids and protein greatly affect the nutritional value of the product. This is due to a decrease in the biological value of the protein, both because of the binding by the free e-amino group of L-lysine, the complex of which with the protein is not cleaved during digestive hydrolysis, and changes in other amino acids (for example, oxidation of the sulfide group of L-methionine); changes in digestibility: - due to a decrease in the rate of lipolysis of essential lipids by pancreatic lipase; - reducing the rate and depth of proteolysis by digestive enzymes; - deactivation of toxic compounds formed during lipid oxidation; - deactivation of lipid hydroperoxides; - deactivation of low molecular weight aldehydes and inhibition of their transformation into hydroperoxides.

Thus, lipid oxidation is also reflected in the properties of cakes and meals and, accordingly, in the fat and meat of animals.

Studies have shown that different classes of fatty acids (EFA, MUFA, W = 3.w = 6 PUFA) in the diet of pigs have a different effect on the activity of tissue desaturases, which is directly reflected in the level of certain fatty acids and cholesterol in meat.

Studies on feeding pigs with the introduction of vegetable oils with a sufficiently high content of oleic acid showed that its content in intramuscular and spinal fat increases, which is favorable both for the stability of the fat itself and its physiological properties, since oleic acid not only has a higher stability to oxidation at high temperatures, but also has a beneficial effect on the heart muscle. Recently, it has been found that it also has carcinogenic properties.

With the introduction of vegetable oils, primarily linseed oil, the level of PUFAs w = 3 changes, including l-linoleic (C18:3), eicosapentaenoic (C20:5), and docosahexaenoic (C22:6) acids.

These data allowed us to make the assumption that acids w = 3 and w = 6 compete in the process of desaturase activation and synthesis of new long-chain fatty acids.

It was found that when rapeseed and flaxseed oils, rich in linolenic acid and having a lower content of linoleic one, are introduced into the feed, the difference in the ratio between w = 6 and w = 3 acids decreases, which is important for preventing atherosclerosis.

It was also found that the use of vegetable oils in the composition of compound feeds for feeding animals during the fattening period causes a change in the oxidative stability of meat, especially during long-term storage. When only 3% of unsaturated vegetable oils are added to the feed, it lowers high-density cholesterol in blood plasma.

Studies have also established a difference in the metabolism of fatty acids depending on the animal gender.

The regulation of the PUFA content in meat by creating feeds with the introduction of various types of vegetable oils opens a revolutionary direction for the creation of meat products with a specific dietary orientation (anti-sclerotic, cardiovascular, therapeutic and prophylactic, etc.).

The addition of antioxidants in the form of a-tocopherol (vitamin E) to animal feed has a beneficial effect on the condition of animals, stabilizes lipids and meat cholesterol to oxidation and reduces the formation of cholesterol oxidation products.

One of the ways of transformation of oils is the formation of trans-isomerized fatty acids, as well as acids with conjugated bonds, both during technological treatments and during the life cycle of animals.

Trans isomers are formed as intermediate products of biohydrogenation in the body of animals with the participation of bacteria, as a result of which trans isomers are present in animal oils, cheeses, milk, beef and lamb, the content of which ranges from 2 to 8%.

In addition, the bacterial flora of the intestines of animals can convert free linoleic acid into its conjugated isomers cis-9, trans-11 and trans-9, cis-11.

They can be formed as methyl esters, which have the same bioavailability as free fatty acids. They are actively formed in the fermentation vat when using feed rations containing small amounts of rough feed.

Conjugated fatty acids are absorbed as free fatty acids and then incorporated into various lipids in the body. They have a number of physiologically beneficial properties.

Conjugated isomers have been found to have cytotoxic effects on some forms of cancer: of skin, pancreas and colon, breast. In addition, it was found that they affect weight loss without reducing the total calorie content of food, are able to reduce the content of total cholesterol, especially of low density one, prevent the accumulation of lipids in the arteries, inhibit platelet aggregation, delay the development of non-insulin dependent diabetes, reduce various inflammatory processes and protect against the development of arthritis.

The largest sources of conjugated fatty acids are milk and dairy products. Their content in milk fat ranges from 0.24 to 1.77% and depends on the breed of dairy cows, their feeding system, as well as on the parameters of milk processing.

As established by studies, their content in dairy products and beef meat is influenced by the feeding system and, first of all, by keeping animals on grazing (grass feeding).

Currently, conjugated fatty acids are used in animal diets to regulate body weight and composition. A decrease in fat formation, e.g. in pigs, has been associated with an increase in lean growth. Reducing the deposition of energy in the form of fat improves feed conversion and allows increasing the yield of lean meat. Typically, conjugated fatty acids are added to the feed of fattened pigs 5 weeks before slaughter.

The addition of conjugated fatty acids to the feed of lactating dairy cows is used to reduce the formation of milk fat. In this case, the principle of reducing energy consumption for fat synthesis is also used. Reducing energy consumption for fat synthesis at the beginning of lactation and in other periods of energy deficit allows reaching the maximum level and fully reveals the potential of cows' milk production. Reducing the synthesis of milk fat can also improve the condition of the animal, allowing the cow to cope with short-term stress (changing feed or environmental conditions) without impairing health, reproductive functions and productivity.

Currently, food and feed preparations of conjugated fatty acids are already industrially produced. For feeding animals, the BASF company currently produces various feed additives, including conjugated fatty acids.

Research of feeding animals with secondary products of fat and oil manufacture (cakes, meals, etc.) was performed, which is associated not only with their high protein content, but also with a full set of biologically active substances - tocopherols, phosphatides, sterols, oil, chlorophyll, carotenoids , trace elements. Fats have a high energy value and, when oxidized in the body, they release 2.25 times more energy than carbohydrates.

Therefore, in order to improve the quality of oils, cakes and meals, the All-Russian Research Institute of Fats has developed a technology that ensures the production of high quality vegetable oils and cakes with a protein mass fraction of more than 40%. Moreover, more than 60% of the protein is in water - and salt - soluble forms. This technology takes into account the fact that the need for protein-containing components for the production of animal and poultry feed in Russia is mainly covered by sunflower cake and meal, and their deficiency is filled by imported soybean seeds, since soybean production in Russia in the total volume of oilseeds cultures are small.

The cake obtained from sunflower seeds can replace soy protein in the feed ration of animals and poultry, since the technology provides for the processing of hulled sunflower seeds only. The advantage of this technology is also the ability to process all types of oilseeds with any oil content. It excludes the traditional technological stages of crushing the kernel, frying the meal, since the twin-screw extruder used in the technology performs these operations in conjunction with extraction. This makes it possible to obtain oils with a low content of oxidation products and high quality cakes.

The oil remaining in the cake, along with protein, due to the low content of oxidation products in it, as well as the presence of a number of biologically active components, ensures high quality of the cake and increases its feed and energy value.

The fractional composition of the protein in the cake is rather little denatured, which will have a positive effect on the cake digestibility. Also, the reduced content of fiber in the cake will allow it to be used as part of a feed mixture for feeding poultry in an amount of up to 26%, which is impossible in the case of obtaining cake from dehulled sunflower seeds. This technology has already been introduced into industrial production.

Obtaining low-oxidized oils that are stable to oxidation and, accordingly, cakes and meals is also possible with the use of various technological methods that reduce the access of oxygen to the material in the process of oil extraction.

As our studies have shown, if preheating of seeds is used to trigger the respiration mechanism, then air will be removed from the capillary-porous structure due to the activation of seed respiration.

We have shown that when the oil passes through the capillary-porous structure, the peroxide number increases in it, which is associated with the presence of oxygen in the pores causing the oil to oxidize. The larger the pore volume, the more oxygen is in them, and, therefore, the more the possibility of oil oxidation in the material increases during the technological operations of oil extraction. But the most important thing is that as a result of the oil movement along the capillary-porous structure, the packing structure of the oil triacylglycerols, which existed in the spherosomes, is destroyed, and accordingly, its protective properties against oxidation are reduced. This oil is more suitable for oxidation, which affects subsequent processing and use.

In contrast to the displacement of air by compression directly in the extruder, at this preparation seeds enter the extruder already in the atmosphere of inert CO2 gas formed by the seeds themselves during respiration or supplied from an external source.

We have shown that when the porosity ratio of sunflower seeds established by us is 60%, almost the entire volume of the intergranular space is filled with carbon dioxide during respiration.

When using this method of preparing seeds for extraction, the resulting oil is of high quality.

On the basis of the performed research, we have developed the latest technologies that ensure the production of low-oxidation and oxidation-stable oils.

There are also other options for technological methods that ensure the extraction of high quality oil and cakes.

This is a method of processing crushed seeds - meal at a moisture content of 14-16% with live steam. Water vapor intensively protects the material from contact with air and inactivates hydrolytic and oxidative enzymes. Then the processed material is cooled to a temperature of 60 °C and kept at this temperature for 20-25 minutes. At that, the moisture content of the material is reduced to 3-4%, it acquires the structure required for pressing and the oil is extracted by pressing. This method ensures the production of high quality oil and cake with low protein denaturation.

This technology is used in the processing of melons and gourds (pumpkins).

Another way to obtain high-quality oils and cakes is the use of microwave heating, the advantage of which is a very rapid local heating of individual subcellular units and the destruction of spherosomes without destroying the cellular structure. The flowing out oil bypasses the capillary-porous structure and does not capture the oxygen contained in it, which ensures the high quality of oil and cake.

Studies have shown that the most promising direction for obtaining special fats for feeding animals and poultry is the creation of compositions based on natural, hydrogenated and fractionated oils, combining the manufacturability and physiological value of fatty components with a relatively low price.

The All-Russian Research Institute of Fats, together with a number of animal farming institutes of the Russian Federation and specialized organizations of animal farming, poultry and veterinary medicine, carried out studies of the feed value of various secondary products of fat and oil manufacture, obtained using technologies that ensure the production of low-oxidized oil and high-quality cake.

It has been found that the deodorization cuts of vegetable oils can be used as a fat additive and a source of crude fat, since they are a rich source of essential fatty acids and a number of biologically active substances - tocopherols (vitamin E), calciferols (vitamin D) and sterols, which affect productivity of animals, lipid metabolism and reproductive functions. The most valuable component of deodorization cuts is vitamin E - a-tocopherol, which also shows a strong antioxidative activity. Its concentration in sunflower oil deodorization cuts is up to 200 mg per 100 g of cuts, in soybean oil - up to 400 mg per 100 g of cuts. The lack of vitamin E causes dystrophy and fatty infiltration of the liver, degenerative changes in tissues. Its presence ensures the correct formation and development of the placenta, and, consequently, the fetus nutrition.

The introduction of tocopherols into the diets of dairy cows leads to an increase in its content in milk and oil, thereby increasing their biological value and stability during storage.

With the introduction of deodorization cuts into the feed ration of pigs, the oxidative resistance of fat and meat is improved. This increases the weight of animals within 2 months by about 11%, and in combination with the introduction of vitamins A and D, up to 22%. The introduction of tocopherol into the diet of laying hens at the rate of 10 mg per 1 kg of feed for laying hens leads to an increase in their productivity by 10.5%.

Phosphatides can be used to increase the productivity of livestock and the weight gain of young animals. They significantly affect lipid metabolism, blood coagulation, hemolysis, agglutination and erythrocyte sedimentation. They contribute to the retention of suspended cholesterol in the blood, have antioxidative, emulsifying and water-retaining properties, and exhibit synergism towards tocopherols. The most active are lecithin and choline. Lecithin is at the same time a phosphorus supplement and should be referred to as the main food substance. Choline has provitamin activity and belongs to provitamins of Group B, plays an important role in metabolic processes in the liver, prevents its degeneration.

Studies have shown that the best results are achieved in cattle consuming the feed with 2.1% phosphatides per dry matter of the meal, bringing the fat content in the meal to 3%. The introduction of phosphatides into herbal flour in an amount of 1-3% ensures the preservation of carotene in the flour by 1.5-3 times. For feeding hens, the optimal feed dose is 2-3% on the dry matter of the feed.

The introduction of phosphatides into the diet of weaned piglets improves the taking of not only fat, but also of other components of the diet.

Phosphatides are used in the manufacture of a whole milk replacer for calf rearing. The All-Russian Research Institute of Fats has developed a whole milk substitute for calf rearing with the addition of phosphatides and vegetable oils or animal fats.

The soap stocks formed during the refining of light oils contain up to 20% oil and, as it was found, their feed value is 3 feed units for cattle, and 3.5 feed units for pigs and poultry. 1 kg of soap stock contains 8500 - 8700 kcal of metabolic energy, which corresponds to 3.4 kg of concentrated feed.

The soap stock of light oils can be used in feeding cattle for the purpose of fattening young and lactating cows and sheep, in an amount of 0.5 kg per day (the fat content of which is 100 g) per 100 kg of animal weight.

For feeding pigs, it is recommended to introduce up to 0.1 kg of soap stock per 1 kg of concentrated feed.

To feed poultry, soap stock is recommended to be introduced directly into the compound feed: for young animals fed for meat (chickens - broilers) - up to 5-8%, for turkeys - up to 3-5%, for ducklings - up to 2-3%. For breeding young animals (60-95 days chickens) - up to 2-3%, for turkeys (5-180 days), ducklings (1-150 days) - up to 1-3%, for goslings (1-180 days) - up to 1-5%. For adult laying hens - up to 3-5%, for turkeys - up to 3-5%, for ducks and geese - up to 1-2%.

It is advisable to introduce soap stock into compound feed with the addition of grass flour (for hens - 3-5%, for turkeys - 7-10%) by weight, followed by granulation.

Another good feed source is oily decoloring clay, which are adsorbed for 30-50%. As well as tocopherols, sterols, free fatty acids, chlorophylls and carotenoids.

As studies have shown, the introduction of fatty decoloring clay into the diet of pigs and poultry in an amount of 3% of the dry mass of feed leads to an increase in animal productivity by 11-15% while reducing feed costs by 16-19%.

Feeding 1 kg of fatty decoloring clay contributes to an additional 350-400 g of net gain.

Thus, fat and oil products are an important component of compound feed, the quality of which primarily depends on the degree of oxidation of oils, including in the composition of oil cakes and other by-products of oil and fat production used for animal feed.

Based on the materials of

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