| More and more SPF chicken production industry are developed in recent years, but theproduction level is still comparatively low, and we have to do a lot of work to improve thesituation. In order to raise the research and production standard of SPF chicken, the studyhad been done on the following respects.1. The nutrition requirement of SPF chicken and the production of its feedThe SPF chicken's feed was irradiated by different dose of 60Co ray in order todetermine the minimum dose which is able to kill the bacteria in the feed completely. TheSPF chicken's feed was sterilized by high pressure steam under different conditions, andthe optimum condition was determined. The nutrient component lose of sterilized feed bydifferent method was examined, then the compensation method and compensation standardwere analyzed. SPF chickens were feed with different sterilized feed and the capability ofgrowth and egg production of the SPF chicken were compared. Then SPF chicken'snutrition requirement was determined according to its special environmental condition andbiological characteristics.The result showed that SPF chicken's feed irradiated by 60Co ray of 10～15 kGy wasnot sterilized completely. But feed irradiated by 60Co ray of 20 kGy was considered to besterilized completely, for there are no bacteria observed after bacteria culture for 30 days.So feed irradiated by 60Co ray of 20 kGy was safety to feed SPF chicken.When feed are sterilized by high pressure steam, the size and shape of the feedpackage have a potent effect on sterilization effect. The feed shouldn't be packed too big insize, it should be packed in thin shape less then 15cm. and there should be staked out someplace through feed packages for high pressure steam to be unobstructed. Packed in perfected size and shape, SPF chicken feed should be considered to be sterilized completelyby steam of 121℃for 20 min.When feed are sterilized by 60Co ray, its vitamin b1, vitamin b12, biotin and folacinloss obviously, but the other nutrition components loss little. However when feed aresterilized by high pressure steam, the crude protein, most of the vitamins, lysine, arginine,and cystine of the feed loss obviously. And the loss of lysine and vitamins must be dulynoted and added in addition.When SPF chicken were fed with steam sterilized feed and 60C0 ray sterilized feedrespectively, in which the loss nutrition components were make up, there were no decideddifference found in their capability of growth and egg production. But SPF chicken didnot like to take the feed sterilized by 60Co ray, because it became too dusty and haddisagreeable odor obviously. There are no obvious harmful effects found on the capabilityof growth and egg production of the SPF chicken which take feed sterilized by highpressure steam.2. Research on SPF chicken's genetic control and capability of growth andegg productionThe genetic variation of different lines of SPF chickens were analyzed by RAPDmethod, the capability of growth and egg production of different lines of SPF chicken wereexamined and the capability of growth were compared between different generations. Thenthe breeding methods of SPF chicken were discussed.The genetic variation of nuclear DNA among 3 lines of SPF chickens(F,M,B)and thecontract pure line (H) were analyzed by RAPD method with 30 individuals, 60 randomprimers were used and 13 primers were selected, 91 amplified fragments were observedand 64 of them were polymorphic fragments.The genetic similarity of different SPF chicken lines were calculated according to RAPD fingerprinting maps. The genetic similarity of line F, line M and line B were 0.673,0.755 and 0.903 respectively, however the genetic similarity of line H was 0.968. Geneticsimilarity of B is the highest but F and M were much lower.The cluster analysis showed the genetic distance between line F and line M was theshortest, they were classified into one group first, then line B and line H were classified,The result was in accord with the importing history of the breeds. The SPF chicken shouldbe selected by the method of group selection and mark-assistant-selection, with theselection target of laying capability and pathogen sensitivity, the underlying group may becomposed of existing SPF chicken flocks, and the inbreeding degree shouldn't be high.The result of capability examination showed that three lines of SPF chicken havesimilar capability of early growth, but they have different capability of late growth,chicken of line B grow much quickly but line M and line F grow slowly. However theyhave similar body weight before lay eggs.Different lines of SPF hens had markedly different laying capability, Hens of line Mhad the best laying capability, Hens of line B and line F had similar laying capability whichis lower than line M. Different generations of the same line had similar growth capability,there was no obviously inbreeding decline observed.3. Research on multiplication of different virus in SPF chicken embryoSPF chicken embryo and common chicken embryo were inoculated with NDV(Lasota),IBV(MA5), AEV(Van Roeke) and IBDV(B87) respectively in order to study themultiplication rule of different virus. The results showed that titer of NDV antibody indifferent batch common hatching eggs were high and uneven, The AGP antibody positiveratio of IBDV in common hatching eggs was from 87.5%～100%. The NDV multiplicationamount inoculated in SPF chicken embryo was 5～20 times of its amount in commonchicken embryo. The lethality rate of SPF chicken embryo was up 65% after inoculated inNDV for 96h, however the lethality rate of common chicken embryo was under 5%. TheHA titer of NDV in SPF chicken embryo allantoic fluid was 2～2.5 higher than common chicken. When inoculated with IBV(MA5), the lethality rate of SPF chicken embryo washigher than common chicken embryo, and the EID50 of SPF chicken embryo was over 10times of common chicken embryo. When inoculated with AEV(Van Roeke), themorbidity of SPF chicken embryo was over 85%, however the morbidity of commonchicken embryo was only 4.5%～5%, and the EID50 of SPF chicken embryo was over 106EID50/ml. IBDV can hardly grow in common chicken embryo, its lethality rate was verylow, so common chicken embryo was not good for IBD vaccine production. But whenSPF chicken embryo were applied, the lethality rate was so high that it is able to reach86.7%～97%, SPF chicken embryo had a high use factor to produce IBD vaccine.In a word, the multiplication of above virus in SPF chicken embryo are more betterthan its multiplication in common chicken embryo, SPF chicken embryo is the excellentmaterial for vaccine production. |
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