The role of polyunsaturated fatty acids in poultry nutrition
Abstract: Fatty acids, especially essential fatty acids, are increasingly important in poultry feeding systems to improve bird health and productivity. Omega-6 and omega-3 have been shown to be unsaturated essential fatty acids essential for poultry physiology, development, reproduction and health benefits. One of the most effective ways to increase the level of polyunsaturated fatty acids in chicken meat products is by adjusting the fatty acid content of poultry diets. This paper reviews the effects of ω-3 and ω-6 polyunsaturated fatty acids on poultry performance, immune antioxidant, egg and meat quality, and provides a theoretical basis for production practice.
Dietary supplementation of polyunsaturated fatty acids may affect poultry immunity, lower cholesterol and total fat levels in blood and egg yolk, and result in poultry products with health benefits for consumers. Among them, polyunsaturated fatty acids (PUFA) ω-6 and ω-3 are important components of cell membranes, and are essential nutrients for maintaining body health and normal physiological functions. Their dynamic balance is important for the stability of the internal environment and normal growth and development of animals. effect. The omega-3 (mainly linolenic acid) and omega-6 (mainly linoleic acid) PUFA ingested by animals are transformed and competed by corresponding enzymes, which is beneficial to the rational utilization of fat in the diet and the lipid metabolism of animals . Foods that provide omega-6 PUFAs include soybean oil, palm oil, sunflower oil, and canola oil. Foods that provide omega-3 PUFAs include certain nuts, vegetable oils, and fish oils (Sujatha T et al., 2011). Fish oil (FO) in turn includes two omega-3 PUFAs: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), so the addition of fish oil to poultry diets may produce omega-3-rich Poultry products (such as eggs and meat). Research has linked high intake of omega-3 PUFAs to a higher incidence of health problems such as type 2 diabetes, obesity and coronary artery disease. Maintaining an appropriate ratio of omega-3 and omega-6 PUFAs not only improves performance, but also reduces these adverse health risks. Therefore, it is necessary to study the appropriate level of adding omega-3 and omega-6 PUFA, and then design the correct ratio.
1. The effect of polyunsaturated fatty acids on poultry performance
The addition of polyunsaturated fatty acids to feed can improve the growth and production performance of poultry. Limited supplementation of fats and oils as a source of fatty acids results in better feed and energy utilization, which in turn improves poultry growth and performance. Ebeid et al. reported that the addition of ω-3 PUFA in the diet had no adverse effects on the growth performance of quails such as final body weight, feed intake and feed conversion rate. However, RajManohar et al. believed that the addition of ω-3PUFA to quail diet had a very significant effect on its weight gain, but had no significant difference on feed intake and feed efficiency. Diets supplemented with polyunsaturated fatty acids can improve poultry live weight, weight gain and feed conversion ratio. And there are few reports of adverse effects on feed intake. In conclusion, dietary supplementation of polyunsaturated fatty acids or oils can improve growth and performance of poultry without adverse effects.
2. Effects of polyunsaturated fatty acids on poultry immunity and antioxidant properties
Supplementation of fatty acids affects both the immune and oxidative status of poultry. The addition of ω-3 PUFA in feed can regulate the immune system through cellular and humoral immune responses, neutralize oxidants and directly or indirectly increase antioxidant levels through fatty acids, reduce the effect of lipid peroxidation, and minimize the risk of oxidative stress. The Al-Mayah study showed that chickens supplemented with 50g/kg fish oil in the diet produced higher antibodies (IgM and IgG) and globulins in post-vaccination serum compared to the control group. In addition to the production of IgM and IgG antibodies, ω-3 and ω-6 PUFAs also affect the proliferation, maturation and cytokine production of lymphocytes and splenocytes. Studies by Fritsche et al. have shown that adding rich ω-3PUFA to the diet can reduce the level of arachidonic acid (AA) in chicken serum and immune tissues by 50% to 75%, while the levels of EPA and DHA increase. Ebeid et al. found that dietary supplementation of less than 35 g/kg fish oil could induce antibody titers in chickens. However, the antibody level of laying hens rich in omega-3 PUFA oil (fish oil or linseed oil) was higher than that of laying hens rich in omega-6 PUFA (corn oil). Ebeid et al. also pointed out that omega-3PUFA in the diet had a positive effect on humoral immunity when the chickens were 42 days old by measuring the antibody titer of Newcastle disease virus (NDV).
In broiler chickens with infectious bursal disease, omega-3 PUFAs showed beneficial immune responses. Studies by Jameel et al. have shown that the antibody titers and the percentages of spleen and bursa of chicks supplemented with fish oil in the diet were significantly higher than those of the control group. Thus, the addition of ω-3PUFA in feed can regulate the immune response of poultry. Early in chick life, omega-3 and omega-6 PUFAs are regulators of inflammation and play important roles in cellular and humoral immunity. They help maintain the integrity of cell membranes, thereby preventing entry or infection by pathogens. In addition, it also has the ability to regulate cytokine production in immune cells through signal transduction.
Adequate intake of ω-3PUFA can improve antioxidant functions such as glutathione peroxidase (GSH-Pχ) activity in laying hens, and reduce lipid peroxidation levels in chicken abdominal fat and serum. Dietary supplementation of sunflower oil significantly reduces abdominal fat deposition in birds compared to supplementation of olive oil and tallow. Soybean oil-rich diets also reduce abdominal fat deposits. This is because diets rich in omega-3 PUFAs improved the gene expression of lipin-1, which regulates triglyceride synthesis, in abdominal fat of chickens. Rahim et al. pointed out that the addition of fish oil can reduce the concentration of malondialdehyde (MDA) and the ratio of ω-6:ω-3PUFA in broilers, which is related to the induction of glutathione transferase (GSH-ST). In addition, diets rich in ω-3 PUFA could enhance the activities of superoxide dismutase, GSH-ST and cardiac GSH-PX and reduce the level of MDA in poultry. However, despite the apparent improvement of PUFAs in poultry immune and antioxidant function, fatty acids must still be evaluated and properly monitored to prevent adverse effects on immune status.
In summary, dietary supplementation of polyunsaturated fatty acids or oils can improve the immune and antioxidant functions of poultry, but fatty acids must be evaluated and monitored to prevent adverse effects on immune status.
3. Effects of polyunsaturated fatty acids on egg quality and nutrition
Omega-3 unsaturated fatty acids include EPA (eicosapentaenoic acid), DPA (docosapentaenoic acid), DHA (docosahexaenoic acid) and LNA (linolenic acid), because unsaturated fatty acids are Human health is beneficial, so increasing the content of unsaturated fatty acids in egg yolk can help reduce the level of harmful cholesterol. And eggs themselves are not rich in omega-3 polyunsaturated fatty acids. Therefore, to obtain poultry eggs rich in omega-3 polyunsaturated fatty acids, it is necessary to add omega-3 polyunsaturated fatty acids to the poultry diet and provide a balanced ratio of polyunsaturated fatty acids (omega-6/omega-3 more Unsaturated fatty acids are 1:1).
Adding a certain amount of peanut oil, fish oil, linseed, fish meal or algae to the diet of laying hens can increase the content of omega-3 fatty acids in laying hens. Ceylan et al. added 15g/kg and 30g/kg soybean oil, rapeseed oil and linseed oil to the diet, and the results showed that there was no significant effect on egg production, egg weight, feed intake, feed conversion rate and live weight. Influence. However, the egg yolks of hens supplemented with soybean oil were lighter in color than those of other oils. When linseed oil and rapeseed oil (30g/kg ration) were added to the diet, there was a significant interaction between the source of fat and the amount added to the diet. Vitamin E and/or organic selenium can increase the stability of omega-3 PUFAs and reduce oxidation in raw eggs, so these factors play a protective role in the sale, storage and cooking of omega-3 enriched eggs.
In summary, adding polyunsaturated fatty acids or oils to diets can increase the content of polyunsaturated fatty acids in poultry eggs and reduce the level of egg yolk cholesterol.
4. Effect of unsaturated fatty acids on poultry meat quality
In the human diet, omega-3 PUFA is significantly reduced and the omega-6/omega-3 PUFA ratio is unbalanced. The reduction in ω-3 PUFA consumption was due to the low intake of marine fish, the main source of ω-3 PUFA. The accepted solution is to produce appropriate functional foods with adjusted polyunsaturated fatty acid content. Increased omega-3 polyunsaturated fatty acids in poultry meat may be an excellent source of these acids in the human diet. The content of omega-3 fatty acids in poultry meat, especially EPA and DHA, can be increased by adding oily fish by-products. Some people think that adding fish oil to the diet can improve the meat quality of broilers. Qi et al. concluded that substituting omega-3 for omega-6 in chicken diets had a significant effect on subcutaneous and intramuscular fat content and meat quality (color and tenderness) in chickens. Omega-3 polyunsaturated fatty acids were significantly increased in the form of linolenic acid, the precursor of the entire omega-3 family. In order to optimize the omega-3 enrichment feeding strategy without affecting the performance of poultry, it is recommended to use crushed or whole flaxseed (including flax oil) before broiler breeding and slaughter.
Omega-3 fatty acids are essential nutrients for maintaining the health, oxidative balance and meat quality of meat. Due to the presence of omega-3PUFA additives in some diets, the fat and cholesterol content in poultry meat will be reduced, and high concentration of PUFA (addition of vegetable oil) in diets will reduce the storage stability of meat. The fatty acid composition of the meat may also be affected, but quality parameters such as pH, tenderness, burn damage, toughness and juiciness of the meat are not affected. Konieczka et al. found that if the ratio of polyunsaturated fatty acids omega-6:omega-3 in the diet exceeds the recommended level, it will cause damage to the intestinal epithelial cells. Whereas a low omega-6:omega-3 PUFA ratio increases the MDA content of tissues such as meat, which can affect meat quality due to changes in peroxidation. At 2% and 3% addition levels, fish oil and low-fat oil increased poultry omega-3 PUFA levels, which in turn improved meat sensory attributes such as appearance, flavor, juiciness, tenderness, and overall acceptance. However, due to the increase of thiobarbituric acid substances, it may cause oxidative damage to the meat quality, thereby affecting the meat quality. This oxidative instability can affect meat quality, thereby reducing consumer acceptance. Oken et al. concluded that the addition of fish-derived products to chicken feed resulted in unacceptable odors in the product. This shows that polyunsaturated fatty acids are very easy to oxidize, and the off-flavors produced in meat are usually related to the taste of fish, thus limiting the adoption of this method. And a balanced supplement of omega-3 and omega-6 is recommended to prevent oxidative damage and loss of meat quality.
In summary, adding polyunsaturated fatty acids or oils, especially EPA and DHA, to diets can improve various indicators of meat quality. However, PUFAs are highly susceptible to oxidative deterioration, resulting in off-flavors, which can adversely affect consumer acceptance, especially when fish products are used. Adding ω-3 and ω-6 PUFA in poultry feed can promote the immune response of poultry, improve the nutritional value of eggs, improve meat quality and improve the growth and development of poultry. Adding peanut oil, fish oil, linseed, fish meal or seaweed to poultry diets can increase the content of polyunsaturated fatty acids in poultry eggs and meat. However, because PUFAs are highly susceptible to oxidation, this can lead to off-flavors in poultry meat, negatively impacting meat quality and consumer acceptance. Therefore, future research should delve into how to produce poultry products with high polyunsaturated fatty acid content, good fatty acid composition, low cost, no negative impact on palatability and quality, and easy to accept by consumers.