| In order to obtain a new method of spray immunization for 1-day-old chicks coccidiosis live vaccine,we screened the immune dilution spray formula of chicken coccidiosis live vaccine by measuring the viscosity,film forming time,Sedimentation rate of coccidiococcal oocysts,droplet size,adhesion rate and feed intake ratio,and observing the results of spray.The main indicators for testing laboratory safety and minimum immune dose evaluation were relative weight gain,mortality and intestinal lesion scores,the number of oocysts per gram of stool,lesion score reduction,anticoccidial index,and organ pathology variety.The results showed:(1)As the concentration of xanthan gum,guar gum,sodium carboxymethyl cellulose,sodium alginate,chitosan and konjac gum increased(in the range of 0.5%~2.0%),the dissolution time of the immune dilution was prolonged and the viscosity was increased,and the film formation time was shortened.It could not be sprayed evenly when the viscosity of the immune diluent was greater than 1822 m Pa.s.1.0%xanthan gum,0.5% guar gum,0.5%,1.0% carboxyl methyl cellulose,1.5%,2.0% sodium alginate,0.5%chitosan can significantly(P <0.05)shorten the film-forming time of the suspension agent.The spray drop immune diluent added with carboxyl methyl cellulose dissolves faster,better fluidity(< 30 min),faster film forming speed(< 700 m Pa.s)and lower cost.(2)The viscosity increases and the film-forming time shortens with the increase in the concentration of carboxyl methyl cellulose in the immune dilution(in the range of 0.25~1.0%).The sedimentation rate of coccidian oocysts in each group was less than 10% within 8 h.The spray drop shape scores of the 1.0 and2.0 mm aperture groups were significantly lower than those of the 0.5 mm aperture group(P <0.05).oxymethyl cellulose concentrations were higher than 85%,and the difference between the two groups was not significant(P >0.05).The feed intake rate of the group with spray droplet size> 200 μm reached 100%after 30 minutes of inoculation.(3)There was no death of chickens in the single-dose and over-dose(10 times)inoculation groups of the immune diluent spray.The body temperature of each group of chickens was 39.6~39.94℃,and the respiratory rate was 48.0~51.6 times/min.The average weight gain of the treatment group was not significantly different from that of the control group(P > 0.05).(4)Oocysts were detected for the first time in the gavage group and spray group 7 days after immunization.The gavage group reached a peak on the 11 th day and the spray group on the 19 th day,and then the number of ovulation gradually decreased.The ovulation trend was consistent the groups and the number of ovulations was not significantly different(P >0.05)among the three spray groups.(5)In the immune challenge group,the survival rate,oocyst reduction rate,RWG,RLS,ACI increased,and the average small intestinal lesion score decreased with the increase in the spray dose.The survival rate was more than 90%,and the scores of lesions in the middle of small intestine of 10/10 chickens were ≤1,and the ACI(177.04)reacheed the intermediate effect when the immunization dose was≥900/bird(PNsx).In conclusion,coccidian oocysts can be uniformly suspended in the immune dilutiona containing 0.5%carboxyl methyl cellulose.The 2.0mm aperture spray droplets are spherical,non-diffusion adhesion,average particle size of 410 μm,chicken feather adhesion rate and chicken feed intake rate within 30 minutes are 85.99% and 100%,respectively.A single dose and an overdose are both safe for chicks.Chickens can get uniform immunity by spraying chicken coccidiosis live vaccine.The minimum inoculation dose is 900 sporulated oocysts/bird. |
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