The influence of feed ingredients on egg quality
2020-12-01
The
modern cage layer industry restricts
chickens to cages. After the chicken eats the full price feed, through biological processing, various nutrients are enriched into the egg. All the material of the egg comes from the feed. Conversely, the change of the feed composition will inevitably directly or indirectly affect the quality of the egg.
Adding vitamin A, vitamin D or some B vitamins in the feed can increase their corresponding content in eggs. The content of mineral elements such as iron, copper, iodine, manganese, and calcium in eggs also changes correspondingly due to changes in their content in the diet. For commercial eggs, the content of vitamins and mineral elements in the eggs affect their edible value. For breeding eggs, it will affect its hatching performance and the health and growth of young birds.
1 The effect of calcium and phosphorus on eggshells
Minerals, calcium and phosphorus are the basic substances that make up eggshells. Chickens have the characteristics of eating according to energy needs. Therefore, the calcium content of high-energy feed should be increased accordingly. Generally, the feed for laying hens contains about 4% calcium, which can basically meet the needs. In the hot summer, chicken intake is reduced, and insufficient calcium intake will easily lead to the decline of eggshell quality. The calcium content should be increased by 0.4%~0.5%. If the shell powder or stone pellets are fed separately in the afternoon, the effect will be better. Laying hens should also increase the calcium content by 0.5% because they must meet both the egg production and bone growth needs. Too high calcium content will also have a counterproductive effect. It will deposit chalk on the surface of the eggshell or form rough wrinkles; in severe cases, it will be excreted in the form of calcium phosphate, causing a lack of phosphorus to produce soft eggs.
Vitamin D3 plays a decisive role in the process of calcium absorption and transportation, so a lack of vitamin D3 will quickly cause calcium deficiency symptoms. When the feed is moldy, the vitamin D3 is destroyed by mycotoxins, which can also cause calcium deficiency. The absorption and utilization of phosphorus is closely related to its source, and it is not easy to absorb from plant sources and can be ignored. Animal-derived or inorganic phosphorus is easier to absorb, called effective phosphorus, and the effective phosphorus content is required to be about 0.5%.
2 The effect of energy and protein on egg weight
The energy level of the diet is highly correlated with the egg weight. The egg weight is affected to a certain extent by the protein level of the diet. Chickens with insufficient energy intake cannot increase egg weight even if the protein content is increased, because protein is consumed as energy. Feeding high-energy and high-protein feeds at the beginning of production, especially animal protein levels, can increase the initial egg weight, and appropriately reduce the energy and protein levels in the later stages of laying, which will help reduce large eggs and improve uniformity. The addition of iron, copper, zinc and selenium to the diet can improve the internal quality of the eggs. If the feed is contaminated by pesticides or heavy metal toxic substances, it will also affect the quality of the eggs.
3 The effect of pigment on egg yolk
All consumers like eggs with orange yolk. Due to its high yield, modern breeds of layer hens have too short time for each egg to form, and the yolk is not colored enough to form a white yolk. The higher the yield, the paler the yolk, which is not as good as the low-yield local chickens. The egg yolk is bright and beautiful, and many useful explorations have been carried out in this regard. According to reports, adding 8-10 g/kg synthetic lutein to the diet can significantly improve the yellow color of the egg. Feeding green feed can also darken the color of the egg yolk, but at the same time it will also cause thinning of the protein and lower egg production rate. It is also reported that adding 1%~2% chili powder, 2% pine needle powder or alfalfa powder can deepen the color of egg yolk by 2~3 Roche colorimetric levels. Long-term storage of feed will cause oxidation of the pigment and affect the color of the egg yolk. Feeding certain drugs, such as Nicarbazine, can make the egg yolk appear mottled.
4 The influence of feed smell on the taste of eggs
Some feeds with strong odor, such as green onions, fish, etc., whose odor can directly affect the taste of eggs. After some feeds are eaten, some products formed in the process of digestion and metabolism can also make eggs produce peculiar smell. The use of fish meal, rapeseed cake and choline in chicken diets is often related to the fishy smell of eggs.
5 The effect of trace elements on eggs
People use the biological processing ability of chickens to develop a variety of therapeutic eggs containing special nutrients, expanding the use of eggs. For example, adding 0.3 g/kg of organic selenium to feed produces selenium-enriched eggs containing 50 μg/piece of selenium. According to reports, eating high-selenium foods can significantly reduce the incidence of lung cancer, liver cancer, and stomach cancer. Feeding 1 g/kg of zinc iodide or calcium iodate to produce high-iodine eggs containing 80 μg/piece of organic iodine to prevent and treat thyroid diseases caused by iodine deficiency; feeding 50 g/kg of zinc to produce High-zinc eggs containing 3,000 micrograms/piece of zinc are used to prevent zinc deficiency in children.
6 The effect of lipids and antioxidants on eggs
Lutein is dissolved in lipids, and its absorption in the intestine may be accompanied by the absorption of lipids. Therefore, adding oil to the diet can improve the color of the egg yolk, especially when the dietary pigment content is low, the effect is obvious. After the pigment is oxidized, it loses its ability to color. Therefore, adding antioxidants to the diet can prevent the oxidation of the pigment and improve the coloring effect of the pigment on the yolk. Vitamin E and ethoxyquin are both effective in this regard, especially when unsaturated fatty acids are added to the feed, the effect is better.
Now people have turned their research focus to the so-called lipid-lowering eggs rich in unsaturated fatty acids, and some progress has been made. For example, feeding the feed rich in red fish oil to produce health eggs rich in eicosenoic acid and using feed rich in flaxseed to produce high linolenic acid eggs are used to reduce blood fat and cholesterol to prevent coronary heart disease.
