The hen’s body produces eggs from nutrients in the food it eats which are stored in the body. A hen in the nature has enough time to prepare to lay a sufficient number of eggs to maintain the breed. Therefore, the hen’s body ensures that there are adequate reserves of nutrients that help the eggs to produce good quality.
Vitamin A (Retinol)
Vitamin A plays the most important role in the development, growth and physical condition of embryos as well as chicks. Vitamin A plays an important role in skeletal development as well as skin formation in chickens. In the absence of Vitamin A, the embryo will stop developing, and the rate of embryo death increases significantly. The newly hatched chicks, especially young ducks will have difficulties in opening their eyes. Sometimes the eyes are sticky and have lots of rheum. Their feet skin is dry and rough.
Vitamin B1 deficiency (Thiamine)
Vitamin B1 is essential for the normal development of embryos. The lack of Vitamin B1 in the diet of breeding chickens will cause the embryos to die at the end of the incubation process. Dead embryos have hemorrhagic lesions in their bodies, swollen bellies, and expanded abdominal muscles. The characteristic manifestation is Polyneuritis in chicks that hatch. Chickens move with a stagger, totter and have some neurological symptoms.
Vitamin B2 deficiency (Riboflavin)
Vitamin B2 is essential for embryo development and for high hatching rates. To some extent, the incubation rate of chickens is proportional to the amount of Vitamin B2 in reproductive chicken feed. However, when the limit is exceeded, Vitamin B2 does not affect the hatching rate anymore. Vitamin B2 ensures the ability of growth and development of the chicks when hatched and avoid the phenomenon of “clubfoot”. Without Vitamin B2, embryos will stop growing, embryo death rate increases especially in the middle and the end of incubation. Vitamin B2 deficiency causes symptoms of Micromelia disease, short legs, bent toes, pinnate hairs and thin embryos, possible malformations in the skull such as short upper beak. The embryos usually die after 9 to 14 days of incubation. Examination of embryos that die in day 16 or later after incubation showed that the primary kidney (wolff tube) is degenerated, edematous, swollen, liver is dark brown or dark green, especially the left liver.
Vitamin B7 deficiency (Vitamin H – Biotin)
In the absence of Vitamin B7, the farrowing rate of breeding chickens does not decrease but the quality of incubated eggs will decrease significantly. When there is a shortage of Vitamin B7 in the feed, the rate of died embryos will skyrocket by the third day of incubation. If there is a less deficiency, then the embryos will die in the middle and the end of incubation. Lack of Vitamin B7 often causes Micromelia disease accompanied by the phenomenon of “short beak”, where dead embryos have short lower beaks, long upper beaks bending downwards, the long bones of the legs are significantly shortened, tibia is bent, and joints are twisted. A thin film may be observed between the third and fourth toes. 1 day old chicks may have neurological symptoms. They tilt their heads on their backs and spin continuously to death. Some chicks may show head-to-belly bend. In addition, Biotin deficiency may cause Perosis diseases in newly hatched chicks, with foot joints and tibia getting twisted, causing tendon to slip out and the chicks will have difficulty walking or cannot even stand up.
Vitamin B9 deficiency (Acid folic)
Vitamin B9 helps ensure a high hatching rate, making newly hatched chicks strong, grow fast and feathers growing normally. If there is a deficiency of Vitamin B9 in the feed of reproductive chickens, the embryonic mortality will increase significantly in the last days of incubation. When vitamin B9 deficiency is high, the embryo becomes stunted and its legs and beak are malformed. Some dead embryos have a bent tibia, flattened heads, small eyes and often have a transparent pouch on the lens. They have lower jaw bone underdeveloped or even have none. The neck of the embryo is long and often twisted. In some cases, they are generalized edema. The organs in the abdominal cavity grow faster than the body so the abdomen is quite enlarged.
Vitamin B12 deficiency (Cobalamine)
Vitamin B12 helps ensure a high hatching rate, although without it, the farrowing rate of chickens may not be affected. In the absence of Vitamin B12, embryonic mortality will increase especially during the period of 26-18 days of incubation. The typical manifestation is that the chick leg muscle is shrunk, the leg is long normally but very small because the muscle does not develop, hemorrhage at embryo leg, embryo body, muscle and tendon. There may be hemorrhage in the cystic membranes and the yolk sac. The embryonic heart is deformed, the pituitary gland is enlarged, the intestinal wall is thin, fat is in the liver / kidney, or the liver is enlarged and pale. Died chicks are mostly associated with a deficiency of Vitamin B12 at hatching.
Vitamin C deficiency (Acid ascorbic)
In 0-3 weeks old chicks and old laying hens, the body does not synthesize enough Vitamin C for living activities, so the addition of Vitamin C will increase mineralization of the body and increase the effective use of minerals. Lack of Vitamin C will reduce the growth rate, egg production, the quality of eggshell and bone, the survival rate, the rate of fertilization and incubation, the immune response and toxins neutralization ability, increase stress in poultry, especially in hot conditions.
Vitamin D3 deficiency (Cholecalciferol)
Vitamin D3 is essential for embryo development because it is closely related to the metabolism and absorption of calcium and phosphorus. In the absence of Vitamin D3, egg quality will decrease before the laying rate is affected. The rate of hatching decreased, the rate of malformed eggs increased. Eggs have thin shells and reduced mineral content inside. As a result, water from the eggs evaporates sharply and reduces the bearing capacity. Therefore, the rate of eggs breaking during transportation and arrangement increases. Embryos will lack both calcium and phosphorus, which may lead to embryonic death. Lack of Vitamin D3 increases embryonic mortality in the second half of incubation, especially in the last days. Embryos die within 10-14 days of incubation with swollen body, is a lot of fluid under the skin, sometimes the skin is congested. However, the excess of Vitamin D3 will also reduce the hatching rate of eggs.
Vitamin E deficiency (Tocoferol/Tocotrienol)
Vitamin E plays an important role in the metabolism of cells and has an antioxidant effect, protecting Vitamin A and the fat of cell membranes from oxidation, creating red blood cells, helping the body to use Vitamin K, etc. Lack of Vitamin E will increase the rate of non-embryonic eggs. After 24 hours of incubation, the embryogenesis and embryo development are slow, the circulatory system is not formed or destroyed immediately after formation. Therefore, blood rings may appear. Many embryos die, especially around 3.5 to 4 days of incubation because of circulatory disorders or hemorrhage.
Vu Chi Thien – Institute for Animal Husbandry