Causes and prevention of calcium deficiency in laying hens with reduced eggshell thinning and easy bankruptcy

Laying hens

The total amount of calcium in laying hens is about 20 ~ 23 grams, and 2.2 ~ 2.3 grams of calcium is excreted for every egg laid, so 10% of calcium in laying hens needs to be replaced every day. Laying hens lack calcium, laying eggs will be reduced, eggshells will become thinner and easily broken, in serious cases, soft-shell eggs, non-shell eggs, and bone brittleness, easy to fracture, and so on.

About 25% of the calcium needed for eggshell formation comes from bone marrow and 75% from feed. The absorption rate of calcium in feed is 50% ~ 60%. Generally, it takes about 4.4 ~ 4.6 grams of calcium for every egg laid. In order to increase hen egg production and reduce egg breakage rate, feed determines the quality and strength of eggshell. The calcium deposition in the bones of the hen is strengthened half a month before laying, so it should be fed with high calcium compound feed from the age of 4 months or when the laying rate is 5%. The best calcium content in the diet of laying hens is 3.2%-3.5%; when the high temperature or laying rate reaches 75%-3.8%, the calcium content can be increased to 3.6%-3.8%, and the eggshell can be thickened by increasing to 4% in a short time, but the calcium content cannot be increased any more, otherwise it is bad for laying eggs. If there is not enough calcium in the feed, it will promote the hen to eat, consume too much feed and increase the cost. at the same time, the hen weight gain, liver medium fat deposition increases, affecting egg production. If the calcium content in the feed reaches supersaturated state, the chicken will lose its appetite, form calcium salt in the body and deposit in the kidney, hinder the excretion of uric acid, seriously cause gout, and so on. If it is not treated in time, the chicken will die one after another. There is a certain correlation between calcium and dietary metabolic energy. If the dietary metabolic energy is high (12970 kilojoules / kg), the calcium content is also high (4.1%-4.6%). If the metabolic energy is low (1106 kJ / kg), the calcium level is also low (3.2%-3.7%).

The best calcium supplement time for hens is from 12:00 to 20:00. When hens are allowed to eat calcium freely, they can adjust their calcium intake, for example, 92% of normal calcium during eggshell formation, while only 68% during non-eggshell formation. Hens that weigh less and eat less should be properly fed with more calcium.

The absorption of animal calcium source in chicken is the best, while that of plant calcium source is the worst. The eggshell sterilized by high temperature is the best source of calcium. The strength of eggshell was the best when shell and limestone accounted for 2 and 3 of calcium sources in diet. When the shell-breaking rate of Bmur4 hybrid chicken reached 3.5% in 61 weeks, after adding 2% of the total feed shell powder in the afternoon, the egg-breaking rate decreased significantly, the eggshell was smooth, and the average egg-breaking rate was only 1.59% at the age of 72 weeks.

The following conditions can easily affect the calcium absorption of laying hens: 1. When the feed calcium content is insufficient and can not find food freely to the sand, it will cause calcium deficiency; 2. Vitamin D has an important effect on laying hens. It can promote the absorption of calcium, maintain the balance of calcium and phosphorus and deposit on bones. The ratio of calcium to phosphorus in feed has a great effect on calcium absorption, and excessive phosphorus will affect the absorption of calcium, and it is most beneficial to the absorption of calcium and phosphorus when the ratio of calcium to phosphorus is kept at 2 ∶ 1: 1.5 ∶ 1. The content ratio of calcium, phosphorus and vitamin D3 has an effect on the strength of eggshell, with 3.0% calcium and 0.45% phosphorus as the best, while the standard of vitamin D3 is 10% 12% of vitamin A. Calcium determines the brittleness of eggshell and phosphorus determines the elasticity of eggshell. There are too many fatty acids and oxalic acid in the feed, which will combine with calcium to form insoluble calcium salts, affecting the absorption of calcium. Chronic dysentery will reduce calcium absorption; 6. Long-term captivity and lack of light, while the supplement of concentrate calcium is less, there will also be calcium deficiency.

The key to the treatment of calcium deficiency in laying hens is to strengthen feeding management, adjust the proportion of nutrients in feed, and pay attention to the addition of fish meal, bone meal, shell powder, eggshell powder or stone powder to ensure the appropriate content of calcium. When the laying hens are about 18 weeks old, the shell powder should be increased to 2% and enter the laying period after 20 weeks of age, and the bone powder content in the feed should reach 1.5%, and the shell powder 5.5% should be increased to 6.5% after 38 weeks of age and when the weather is hot. When the laying rate reaches 80%, the calcium content in the diet should reach 3.5%; when the laying rate is less than 80% or greater than 65%, the calcium content is 3.4%. When the laying rate is less than 65%, the calcium content is 3.2%. In addition, multivitamin can be added to the feed, cod liver oil can be added if necessary, and chickens can be exposed to the sun or ultraviolet light to increase the source of vitamin D. All factors that can increase intestinal acidity are conducive to the dissolution of calcium salts and promote the absorption of calcium. What should be reminded in particular is that excessive calcium should be prevented when preventing calcium deficiency and calcium supplement.