الفهرس 
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Abstract
The aim of the present work is to study the impact of different doses of BCG vaccine on the skin sensitivity useing single intradermal comparative tuberculin test, cellular and humoral immune response as well as blood leucogram in beef cattle.
Fifteen mixed breed beef cattle were used in this experiment which divided into five groups. Each group vaccinated with 5, 10, 50 and 100 human doses of BCG vaccine respectively. The last group was left as a control one. The single intradermal comparative tuberculin test gave positive tubrerculin reaction 2 months post-vaccination in all vaccinated animals. The positive tuberculin reaction persisted up to 10 and 16 months post vacciantion with 5 and 10 human doses of BCG vaccine respectively and then turned negative to the end of the study while in both 50 and 100 human dose, the tuberculin response remained positive allover the whole period of the work (24 months).
The results of phytohemagglutinin skin test in beef cattle showd that the interaction significance in the mean skin fold thickness after vaccination between the vaccinated groups and the control one using the least significance difference (L.S.D) at 5% was present. This significant difference in reaction existed up to 15 and 19 months post-vaccination in animal groups vaccinated with 5 and 10 human doses of BCG vaccine respectively but lasted during the whole period of the study in animal groups vaccinated with 50 and 100 human doses.
The IFA test carried out on beef cattle sera revealed that, the appearance of specific antibody responce in all vaccinated animal groups was cleared at one month post-vaccination. The humoral antibody response in animals vaccinated with 5 and 10 human doses of BCG vaccine was positive to IFA technique till the 10th and 16th months post vaccination respectively. Although animals vaccinated with 50 and 100 human doses gave positive antibody response up to the end of the study.
The leucocytic count of beef cattle to different doses of the BCG vaccine showed that leucograms achieved a significant increase in leucocytes and also the absolute value of neutrophils, monocytes and eosinophils, one week post BCG injection while there was insignificant difference in lymphocytes and basophiles during the whole period of the study in all vaccinated animals.