Effects of vitamins on eggshell of high quality eggs

What is the appearance symbol of a high-quality egg? From the consumer's point of view, the first sense is eggshell color and hardness, which is the first level to decide whether consumers buy. From the production enterprise, the eggshell quality is poor means that can't sell, eggs are not qualified, this is the decision of the production enterprise products out of the first.

So how do eggs come into being? The first is the formation of yolk, yolk from the formation of 10 days to the ovarian discharge time, its growth rate is very fast, 6 days before ovulation diameter can be increased from 6mm to 35mm, hen ovaries often have 5 to 6 large, mature yellow follicles and many color white, immature small yolk. Next, the egg white is formed, in the enlarged part of the fallopian tube, where the albumin is secreted to wrap the yolk. Then the isthmus of the fallopian tube forms the eggshell membrane, which is divided into the inner shell membrane and the outer shell membrane. Finally, the egg shell forms in the uterus, which is the part of the egg that stays the longest during the egg formation process and where the shell is formed and pigmented.

Eggshell pigment is mainly composed of three components: protoporphyrin Ⅸ(C34H34N4O4), biliverin (C33H34O6N4) and biliverin zinc chelate [1-2]. Protoporphyrin Ⅸ forms brown, yellow or pink; Biliverdin and its zinc chelate form green. The three components form different colors in different proportions [3]. The pigment in brown eggshell is mainly protoporphyrin Ⅸ, and the pigment in green eggshell is mainly biliverdin. Eggshell pigment is closely related to heme. The formation of heme requires the participation of protoporphyrin Ⅸ and biliverdin can be formed from the decomposition of heme IX.

As we all know, calcium and vitamin D deficiency will lead to soft shell eggs or thin shell eggs, seriously affecting egg quality, vitamin D3 is more related to eggshell strength and thickness. Vitamin D and its hormone metabolites act on the mucosal cells of the small intestine to form calcium-binding proteins, which can promote the absorption of calcium, magnesium and phosphorus. Egg shells mainly contain calcium and magnesium carbonate, so that eggshell pigment can be uniformly deposited on the surface of the eggshell, making the eggshell smooth and shiny.

Other vitamin deficiencies can also affect eggshell quality.

Vitamin C is an antioxidant in the body, but also can enhance the activity of the thyroid, promote calcium metabolism, thereby improving eggshell quality, improve color, make the eggshell smooth, so that pigment on the eggshell uniform deposition. In addition, vitamin C can improve the utilization of iron in the body and increase the available Fe2+ in the body of laying hens, which contributes to the formation and transport of protoporphyrin Ⅸ/ heme, the formation of eggshell pigment and the improvement of eggshell color [4].

Vitamin A is essential to maintain the sound of all epithelial tissues and is related to the development and integrity of the epithelium of the genital tract. Protoporphyrin Ⅸ can be secreted by the eggshell gland in the skin cells of the uterine wall, so vitamin A can play a certain role in the formation and deposition of protoporphyrin Ⅸ, thus affecting the eggshell color [5].

Vitamin E has a certain effect on the gloss of eggshell color. It has antioxidant function, can maintain the integrity and function of cell membrane, and also has the hemolysis effect of peroxide in heme synthesis.

Vitamin B6 was the coenzyme of all amino acid transaminases and it promoted the synthesis of heme, which was the raw material of iron-porphyrin synthesis. Lack of vitamin B6 is likely to lead to fallopian tube atrophy, which significantly reduces the content of hemoglobin in red blood cells [6], and thus has a certain impact on eggshell color.