Effects of Feed Nutrients on Product Quality of Waterfowl Eggs

Waterfowl products  include poultry eggs and poultry meat. The production of waterfowl products involves many links such as nutrition, species, breeding environment, slaughtering and processing, storage and transportation. Among them, feed nutrition is closely related to product quality. To produce high-quality waterfowl products, it is necessary to use high-quality feed with balanced nutrition, no residue, and no pollution.
Egg quality mainly includes egg weight, egg shell quality, egg yolk color, egg composition and flavor and other indicators. Various nutrients in the feed affect the quality of eggs.
1 Effect of Feed Nutrients on Egg Flavor
Egg flavor is largely affected by odorous substances in feed. For example, sinapine in rapeseed meal is related to the production of fishy eggs. After egg-laying poultry ingest rapeseed meal, sinapine is decomposed in the digestive tract to produce choline, which is then converted into trimethylamine. Trimethylamine is a volatile substance with a fishy smell. When the content of trimethylamine in the egg is above 1 μg, the egg can have an obvious fishy smell. Fishmeal in the diet can also cause fishy eggs. Excessive use of chili powder in the diet to color the egg yolk during production will also affect the flavor of the egg. When the amount of chili powder in the diet reaches 0.4%~1.0%, the egg yolk will feel slightly bitter and astringent when eating.
2. Effects of Feed Nutrients on Egg Components
Certain trace components in feed can regulate egg yolk cholesterol content. Adding 100~250mg/kg Cu2+ to the diet can reduce the cholesterol in egg yolk from 12mg/g to 8mg/g, which is a 30% reduction. β-cyclodextrin, chitosan, allicin and organic chromium can also affect the concentration of egg yolk cholesterol. In recent years, nutritionists have regarded eggs as a carrier of nutrients that are lacking or extremely low in traditional eggs, such as turning eggs into food that can supply omega-3 fatty acids, and feeding eggs derived from flaxseed or The α-linolenic acid (ALA) in canola can strengthen the omega-3 fatty acid in egg yolk and increase the ratio of omega-3 to omega-6 fatty acid in egg. The main feed ingredients used to fortify protein omega-3 fatty acids are fish oil, rapeseed, perilla seed and perilla seed oil, linseed oil, etc.
Dietary vitamin levels have a great influence on vitamin content in eggs. The transfer efficiency of vitamins from diet to eggs is as follows: vitamin A (60%-80%) > riboflavin, pantothenic acid, biotin, vitamin B12 (40%-50%) > vitamin D3, vitamin E (15% ~25%) > vitamin K, vitamin B1 and folic acid (5%~10%).
Adding iodine-containing kelp extract to egg yolk can increase the iodine content by 2.1-5.8 mg per 100 g of egg yolk. Without adding kelp extract, the iodine content per 100 g of egg yolk is below 0.5 mg. The currently produced eggs fortified with trace elements mainly include: high-iodine eggs, high-selenium eggs, high-zinc eggs and high-iron eggs, etc. In addition, complex trace element eggs can also be produced, such as eggs rich in selenium and iodine at the same time.
3 Effects of feed nutrients on eggshell quality
In addition to factors such as breed, age, environment, disease and drugs that affect eggshell quality, dietary calcium, phosphorus levels, trace elements and vitamins also have an impact on eggshell quality.
3.1
Calcium Calcium accounts for 38% ~ 40% (2.4 ~ 2.6g) of the eggshell weight, so the hen needs about 2.5g calcium to synthesize eggshells every day. Female birds usually store the dietary calcium eaten during the day and release it to the reproductive tract to form eggshells at night, because the eggshell formation of female birds is most active at night, so feeding oyster shells or limestone particles at night can significantly improve eggshell production. Quality effect, because these calcium sources can stay in the digestive tract until night and be absorbed and utilized by the hen. Dietary calcium levels ranged from 3% to 4%, and eggshell strength significantly increased linearly with increasing calcium levels. Egg poultry intake 3.75~4.00g of calcium per day to form the best eggshell.
3.2
Phosphorus Phosphorus, like calcium, is an important component in the formation of eggshells. Calcium determines the fragility of eggshells, and phosphorus determines the toughness and elasticity of eggshells. The dietary phosphorus level of laying poultry is suitable at 0.4%, which can not only meet the nutritional needs of laying eggs, but also ensure the best eggshell quality. Laying poultry need about 400mg of available phosphorus per day to maintain egg production and ensure eggshell quality, but when the available phosphorus in the diet exceeds 500mg per day, the eggshell quality will decrease significantly.
3.3
Manganese Manganese is essential for the normal formation of eggshells, because manganese plays an important role in the synthesis of protein-mucopolysaccharides, and this glycoprotein is associated with the initiation of eggshell calcification. If manganese supply is insufficient, egg production and hatchability decrease, eggshells become thinner, and scarred eggs are produced. Studies have shown that adding 55~75mg/kg manganese to the feed can significantly improve the eggshell quality, and reducing it to 7mg/kg will cause the eggshell quality to decline regardless of the calcium and phosphorus content in the feed. Excessive manganese in the feed affects the absorption and metabolism of calcium and affects the eggshell quality. 3.4
Mg Magnesium salt can increase the activity of phosphatase in the poultry and indirectly affect the strength of the eggshell. Magnesium deficiency in the diet of laying poultry will lead to eggshell quality. The magnesium content in the shell decreases, the eggshell becomes thinner, and the eggshell quality and egg production rate decrease. The requirement of magnesium in the diet of laying poultry is 400mg/kg, if magnesium is excessive (500mg/kg), it will also make the eggshell thin. When limestone powder containing 1.5% magnesium was used as a supplementary feed calcium source, the egg production of hens decreased sharply one month later, the number of sand shell eggs increased, and the serum calcium content decreased.
3.5
Zinc Zinc is the coenzyme of carbonic anhydrase, and the formation process of calcium carbonate in eggshells is related to the activity of carbonic anhydrase. Eggshells are formed in the eggshell glands, which require an adequate supply of calcium ions to the eggshell glands and an adequate supply of carbonate ions to the eggshell glands. Phosphoric anhydrase catalyzes CO2 and H2O to form bicarbonate, further reacts to form carbonate, and then combines with calcium ions to form calcium carbonate. Insufficient zinc in the diet will reduce the activity of carbonic anhydrase, which will reduce the quality of eggshells.
Calcium competes with zinc, copper, and manganese for the same absorption site in the intestine, which seriously affects the biological availability of zinc and manganese. Therefore, an appropriate ratio between elements is also one of the key steps to improve eggshell quality and reduce egg breaking rate .
3.6
Vitamin D3 participates in the metabolism of calcium and phosphorus in the body. It is not only a regulator of calcium and phosphorus absorption and bone tissue calcium and phosphorus metabolism, but also necessary for the transformation and deposition of calcium and phosphorus in eggshell glands. After vitamin D3 is ingested into the body, it is converted into 25-(OH) 2-D3 in the liver, and then into the active metabolite 1, 25-(OH) 2-D3 in the kidney, which induces duodenal Synthesis of calcium-binding protein in the intestinal mucosa and eggshell glands, thereby promoting calcium absorption and deposition in the eggshell. Hens deficient in vitamin D3 began to lay thin and soft shell eggs within 4 weeks. When 1500IU/kg vitamin D3 is added to the diet, excellent eggshell quality can be obtained. In the case of heat stress, supplementing vitamin C in drinking water or diet can help improve eggshell quality.
3.7
Electrolyte balance In the process of eggshell formation, due to the production of carbonate radicals in the eggshell glands: HCO3----CO32 -, the release of H+ increases, the acidity of uterine fluid and blood increases, and the pH decreases. Shell formation is unfavorable. Electrolyte balance (dEB) has a major impact on the acid-base balance in the body, thereby affecting eggshell quality. Since Na+, K+, and Cl- in poultry feed have a greater impact on electrolyte balance, that is, d EB = Na++ K+- Cl-. In order to ensure the quality of eggshells, the appropriate range of d EB, that is, the sum of the milligram equivalents of Na+ and K+ per kilogram of feed minus the milligram equivalents of Cl- (m EQ/kg) is generally 250~400 m EQ /kg. Some cations can reduce the production of HCO3- in the eggshell glands, and then affect the formation of eggshells. Increased dietary acidity (high chlorine or high phosphorus) is harmful to eggshell quality; while alkaline treatment (restricted intake of Cl- or adding Na HC03) is beneficial to improve eggshell quality.
4 Effects of feed nutrients on egg yolk color
Egg yolk affects the consumption of poultry eggs to a certain extent. Generally, the darker the egg yolk, the more popular it is with consumers. The color of egg yolk depends largely on the diet. In order to maintain a moderate amount of pigment deposition in the egg yolk, it is only necessary to ensure that the diet contains a sufficient amount of pigment substances. Poultry itself cannot synthesize lutein, and the ideal egg yolk color depends on the quality and quantity of lutein in the diet. Lutein and zeaxanthin are the main lutein suitable for yolk deposition in natural plants, and the feed ingredients with higher content are corn, corn products, grass meal and alfalfa. Carotene is a fat-soluble substance, so low fat level in the diet will affect its absorption, and then affect the coloring of egg yolk. Usually adding 3% to 5% animal fat to the diet can improve the coloring effect. Short-chain saturated fatty acids and fats, long-chain unsaturated fatty acids and fats can promote the absorption of lutein, while long-chain saturated fatty acids and fats have little effect on the absorption of lutein.
If there is not enough vitamin A in the poultry diet, it will convert dietary carotenoids into vitamin A to meet nutritional needs; conversely, excessive vitamin A in the diet will competitively inhibit carotenoid absorption and The optimal amount of vitamin A in the diet is 12000IU/kg from the perspective of coloring. Vitamin E has the function of protecting fat and fat-soluble substances from being oxidized. When vitamin E is insufficient in the diet, the coloring effect will decrease.
Ca+ in the diet competes with lutein in intestinal absorption, and the transport of lutein in the blood depends on lipoproteins, and the affinity of Ca+ to lipoproteins is greater than that of lutein. Therefore, if the amount of Ca+ is too high, it will cause competitive inhibition of the absorption of lutein and make the coloring effect worse.
Mycotoxins are important factors affecting egg yolk coloration in feed. Mold not only consumes the nutrients in the feed and deteriorates the feed, but also prevents or reduces the secretion of bile and reduces the absorption, transportation and deposition of oxidized carotenoids in the small intestine.
Dietary nutritional imbalance can affect the absorption of lutein in the intestine. Improper levels of vitamin E, methionine, choline and trace elements in the feed can cause coloration differences. In addition, too much salt in the feed, especially too much nitrate, will also affect the coloring effect. Normal poultry egg white has a slight yellow-green color, which comes from riboflavin. If the riboflavin in the laying poultry diet is excessive, the color of the egg white will deepen.
5 Effect of feed nutrients on egg weight
Egg weight is affected by many factors, including heredity, body weight, age, feed intake, feed nutrition and certain drugs, among which the feed nutrients that affect egg weight are mainly energy, protein and linoleic acid levels. Dietary energy concentration affects egg weight. Adequate feed energy supply is conducive to protein metabolism in poultry, thereby increasing egg weight; insufficient energy supply leads to decreased egg weight and egg production. Linoleic acid is one of the essential fatty acids in poultry, which is involved in fat synthesis and metabolism, affects the quality and weight of egg yolk, and thus affects egg weight. Adding linoleic acid to the diet can increase egg weight. When linoleic acid is severely deficient, the egg weight of adult hens is only 65% of that when linoleic acid is abundant. Too low dietary protein level not only reduces egg weight, but also affects egg production rate.
It can be seen that feed nutrients have a great impact on the quality of eggs, and to a certain extent determine the consumption of eggs. Eliminating the adverse effects of feed nutrients on egg quality and increasing their beneficial effects still need to be explored by animal nutrition experts.