The Transfer Rule Of IgY In Chick's Organs And The Effects Of Dietary IgY On Growth Performance And Immune Function Of Chicks During Early Development

This experiment was conducted to study the transfer rule of IgY in chick's organs and the effects of dietary IgY on growth performance and immune function of chicks. The reported results provide a basis for the actual application of IgY as an animal feed additive. Trail one:IgY transfer rule in chick organsTwenty highland male chicklings were euthanised to collect organs samples at 24,48,72, 96,120 and 144 hours after hatching, respectively. At each analyzed stage, yolk sac, digestive organs (gizzard, hepatic and intestine) and immune relative organs (spleen, thymus and bursa fabricius) of cocks were weighed, and the IgY level of these organs using chick IgY ELISA kit was detected. The results showed that:2) IgY concentration was between 170-1000 ug/mL in chick's yolk sac, muscular stomach, intestine, liver, thymus, spleen and bursa. The IgY concentration was not significantly changed among these detected tissues of chicks at each analyzed stage.2) The content of IgY was gradually declined in yolk sac during the age of 24-144 hours. The content of IgY was decreased significantly every 24 hours from the 24-hour age to the 72-hour age (P<0.05).3) The content of IgY in gizzard, hepatic, intestines, duodenum, jejunum and cecum was initially raised and reached the peak at 96-hour age (gizzard) or 120-hour age (hepatic, intestines, duodenum, jejunum and cecum), and then decreased along with the age. Besides, the IgY content was increased during 96 to 144 hour age compared with 24 hour age. The content of IgY in ileum and rectum was increased along with age. The content of IgY in digestive organs at 24 hour age was significantly lower compared to that at 96,120,144 hour age (P<0.05).4) The tendency of IgY in bursa fabricius, spleen and thymus was gradually increased. The content of IgY in immune organs with 24,48,72 hour age was significantly lower compared with that of 120,144 hour age (P<0.05).5) The IgY content of gizzard was significantly higher than the gut's and liver's during 24 to 144 hour age (P<0.05); The IgY content of Liver was higher than that of the gut in chicks at 72,96,120 and 144 hour age (P<0.05), respectively. The IgY content of the intestine was higher than the IgY content of the large intestine from the 24-hour age to the 144-hour age (P<0.05). The IgY content of the spleen was significantly lower than that of the thymus and fabricius in chicks at the age of 24 and 48 hours (P<0.05), respectively. The IgY content of spleen and Fabricius were significantly lower than that of thymus from the 48-hour age to the 120-hour age (P<0.05).Trail two:Effect of IgY on growth performance and immune function of chicksTwo hundred and forty 1 day old Roman rooster, with same batch of hatching and similar body weight, were randomly divided into 2 groups (control and experimental groups),20 birds in each group. Control group was fed with basal diet, and the experimental group contained 0.1% IgY on the basis of the control.In the feeding period, respectively at the age of the 1,3,5 weeks, 2 chicks with average weight of each replicate were weighed, slaughtered, and blood was collected, the serum biochemical parameters and slaughtering performance were determined. The results showed that:1) Growth Performance:Compared with the control group, dietary supplementation of IgY significantly increased body weight and average daily gain at the age of 1 week and 5 week (P<0.05). IgY significantly increased chicks'liver weight, muscular stomach weight, cecal weight at the age of 1 week; significantly increased muscular stomach weight, duodenum length at the age of 3 weeks; significantly increased liver weight, glandular stomach weight, and jejunum weight at the age of 5 weeks (P<0.05).2) Immunity Performance:Compared with the control group, IgY significantly increased thymus weight of chicks at the age of 1 week and 5 weeks and increase the spleen weight at age of 1 week (P<0.05); IgY significantly increased chicks'serum globulin content at the age of 1 week; and serum total protein and globulin content at the age of 3 week; and serum urea nitrogen level at the age of 5 week (P<0.05); IgY significantly increased the number of blood lymphocytes at the age of 5 week (P<0.05); IgY significantly increased sIgA content in the intestinal age of 1 week; IgY significantly increased serum lysozyme content age of 1 week (P<0.05); IgY significantly increased serum a-interferon content age of 1 week (P<0.05); Serum interleukin-2 content was significantly increased at the age of 1 week and 3 weeks (P<0.05); IgY had no significant effect on the IgY content of Bursa, spleen, thymus (P>0.05).Therefore, the transfer rule of endogenous IgY as follows: ? The IgY were detectable in intestine, thymus, egg yolk, liver, gizzard, spleen, bursa and serum during 24 to 144-hour age. ? Along with the development process of chicks from 24 to 144 age, the tendency of IgY in yolk sac is decreased gradually, the tendency of IgY in organs is progressively increased. The changes of the IgY content indicated that newborn chicks during the early development period absorbed IgY constantly from yolk sac to tissues and organs. ? The order of IgY total content in chick's organs from high to low is:gizzard, liver, intestine, thymus, bursa and spleen.Dietary supplementation of exogenous IgY can enhance growth performance and immune function at 1-5 weeks. But from the perspective of improving immune function, effect of brood early is more obvious.