| For exploring the laboratory efficacy and safey of quadrivalent live vaccine with five strains against chicken coccidiosis, providing scientific basis for clinical application and according to the veterinary biological products quality standard assembly(2009) and controlling the quality of the vaccines with the PRC ministry of agriculture 683 announcement of veterinary biological products experimental study on the technology guiding principles, using appropriate age of SPF chickens and taking blood stools, mortality rate, relative weight gain rate (RWG), average lesions score (duodenum, jejunum and caecum) and reduction of lesion score (RLS) as the main test index, respectively worked on attacking mixed virulent strains test, formula research, laboratory efficacy, laboratory safety and stability test. The results showed that:1.33 day-old SPF chicks were attacked by mixed virulent strains. Results indicated that when the vaccination dose of E.tenella (Tsx), E.necatrix (Nsx), E.acervulina (Asx) and E.maxima (Msd/Msx) respectively were 4.00×104, 11.00×104,20.00×104,15.00×104 and 15.00×104 oocysts per chicken, the attacked group at least nine chickens all the intestinal lesion score were 3.00 or higher, the mortality was higher than 40.00%, the mortality and average lesion score of blank control group were 0.00, confirmed this dose for virulent strains attacking test of chicken coccidiosis quadrivalent live vaccine with five strains.2. Immuned the SPF chicks respectively at 4 and 14 age, attacked with mixed virulent strains after 14 days. Results showed that relative weight gain rate and RLS of immuned and attacked chicks rised as higher vaccination dose, average intestinal lesion scores was lower. When the first and second vaccination dose of E.tenella (PTsx), E.necatrix (PNsx), E.acervulina (PAsx) and E.maxima (PMsd and PMsx) were 1000.00/2000.00,200.00/400.00,400.00/800.00 and 200.00/400.00 oocysts per chicken, the mortality of immuned groups were 10.00% or less, all the intestinal lesion score of the immune and attacked group at least eight chickens were 1.00 or less, it had a good immune efficacy. Therefore, the minimum first/second vaccination doses of PTsx, PNsx, PAsx and PMsx/PMsd were 1000.00/2000.00,200.00/400.00, 200.00/400.00 and 100.00/200.00 oocysts per chicken, so the recommended vaccination first/second doses were 1500.00/3000.00,300.00/600.00,300.00/600.00 and 150.00/300.00 oocysts per chicken.3. First immuned at different age (2d,3d,4d and 5d) with recommended vaccination dose, after 10 days proceed the second immune, attacked with mixed virulent striains 14 days later. It was founded along with the increase of the first immune age, RWG, RLS and intestinal lesions scores were lower. After attacking virulent strains more than 4 day-old chickens did not appear death,the average lesion scores of at least eight chickens were 1.00 or less, it had a good immunity. Therefore,4 day-old was the minimum age for the first vaccination.4. Using the recommended vaccination dose for the first vaccination of 4 age SPF chicks,different time intervals(7,8,9 and 10 day) for the second vaccination, attacked virulent strains 14 days later. Results showed that with the extension of interval time, RWG and RLS rised, intestinal lesion scores reduced. The mortality of more than 9 days groups were less than 10.00%, the average lesion scores of at least eight chickens were 1.00 or less, the RWG and RLS were 75.00% or higher, it had a good immunity. Therefore, the interval for the second vaccination was at least 9 days.5.Using recommend vaccination dose at 4 and 14 age SPF chicks, attacked with mixed virulent strains at different time intervals (6,10,14,39,60 and 91 day). Results showed all the mortality were 10.00% or less, the intestinal lesion scores of after 10 days attacked group at least eight chickens were 1.00 or less, RWG and RLS were 75.00% or higher, it had a good immunity; with the extension of breeding time the immunity rised at first then declined, the intestinal lesion scores attacked at 91 days group at least eight chickens were less than 1.00, the mortality was 10.00% or less, it still had a good immunity. It suggested that the immunity produced 10 days after the second vaccination, the good efficacy should keep at least 91 days after the second vaccination (105 day-old).6. Using recommended vaccination doses for 4 and 14 day-old chicks which were flat online and flat on the ground, attacked with mixed virulent strains 14 days later. Results showed that the RWG of two groups were 80.00% or higher, RWG between the two groups had no significant difference(P>0.05), but it were significantly lower than the blank control group(P<0.05); the two groups had no death, the intestinal lesion scores of at least eight chickens were 1.00 or less, RLS were 75.00% or higher, it had a good efficacy, it suggested that flat online or flat on the ground had no effect on growth performance(weight) of the chickens; flat online or on the ground had no significant influence on immunity, the only difference was that the immunity of flatting on the ground was superior to the flat online.7. Proceed a single dose, a single dose repetition and a super dose (10,20,30 and 100 times of the recommended doses) inoculation test. Results showed that, in addition to poisoning of most chickens inoculated by potassium dichromate in 100 times group, the mortality was more than 80.00%, the chickens of other groups had no death, the intestinal lesion scores of at least eight chickens were 1.00 or less; compared with the blank control group the average weight gain had no significant difference (P>0.05), it showed that in addition to 100 times,10 times,20 times,30 times of the recommended vaccination doses were safe for chickens.8. Using different shelf life (1,2,3,6 and 9 months) vaccine to chickens at 4 and 14 age, attacked with mixed virulent strains 14 days later.Results showed that with the extended of shelf life, the RWG and RLS gradually decreased, but the average intestinal lesion scores increased; although the mortality increased, it were also less than 10.00%, the intestinal lesion scores of at least eight chicken were 1.00 or less, it had a good immunity. It showed that with preservation conditions of 2?8? and 2.5% of potassium dichromate solution, the shelf life of the vaccine was at least 9 months. |
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