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This study focused on the effects of different vegetable protein content in calf milk replacer on Immune Organs, Serum IgG, Serum IL-1, Serum Hormone,Serum Enzyme,Anti Oxidation Defence System, Health condition, blood biochemical index, intestinal mucosal immune of weaned dairy caves, and provide technical reference for developing milk replacer with high quality and low cost .Holstein male calves (n=20) were purchased at 1 d of age, housed individually within an nvironmentally uncontrolled facility, were randomly allotted in batches to receive 1 of 4 experimental treatments. The alternative protein ingredient based on soy protein concentrate, full fat soybean, corn gluten meal and milk powder were evaluated in calf milk replacer. After born, all calf were fed colostrum for three days. In group A , B and C, Holstein male calves were fed calf milk replacers which containing 60%,70%,or 80% of crude protein as vegetable protein respectively, and group D were fed whole milk as control group.The trial result showed that had prominently increase on the spleen index , thymus index and thymus cortical thickness of calves group C and D, and other groups had no obvious difference on these indexes. Milk replacers had no obvious difference on the number of thymus cortical, areas of splenic corpuscles, Serum IL-1, lsozyme. The above result showed that the milk replacer containing 80% of crude protein as vegetable protein had effect on the Non-specific Immune Functions of calves.There had no obvious difference on T lymphocyte transformation rate between milk eplacer groups and control group. In whole experiment, there had difference for the levels of serum IgG between group C and D,and other groups had no obvious difference on this index. These results showed that plant protein had no effect on cellular immunity, but when the content of vegetable protein reached 80%, milk replacer had influence on humoral immunity.The level of cortisol in group C was higher than group D.The concentration of cortisol was lowest in group B. Milk replacers had no difference for GH,TP, ALB and BUN. Serum level of the total antioxidant capacity (TAOC) was highest when the content of vegetable protein reached 70% and Serum level of NO was highest when the content of plant protein reached 80% in milk replacer.The concentration of SIgA, the population of goblet cells of duodenum, forepart jejuna ,and midpiece intestinal in group C were lower than group D, and other groups had no difference for these indexes in all intestinal segments. The population of intestine epithelial lymphocyte of duodenum in group C was higher than group D, and other groups have no difference for these indexes in all intestinal segments. There had difference on the population of mast cells of duodenum, forepart intestinal between milk replacer groups and control group, but had no difference in other intestinal segments. These results showed that vegetable protein had more effect on forepart intestinal than on back end intestinal.It was concluded that milk replacer which contented 70% plant protein was beneficial to improve the immune function of the calves, and calf can adapt to high level plant protein better after born 30 days.
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