Age-dependent changes of the caecal fermentation pattern were studied in female chickens using in vitro batch incubation technique. Chickens were sequentially killed at the age of 1, 2, 3 and 4 months, their caecal contents added to a broth with starch and incubated at 39 °C for 20 h. Net productions of short-chain fatty acids (SCFA), succinate, ethanol, lactate, methane, hydrogen and ammonia were determined. Methanogenesis was absent in caeca of 1-month-old chickens. Production of methane started in the second month and doubled in the third month of age. The start of methanogenesis was accompanied by changes of the fermentation stoichiometry. The production of succinate ceased and that of ethanol decreased to less than one tenth. There were no major changes of the caecal fermentation pattern in the fourth month of age. The ammonia production increased in the second month, indicating increased deamination activity. No major shifts in SCFA molar composition dependent on age were found. Calculated hydrogen recoveries suggest a decrease of reductive acetogenesis until 3 months of age. It can thus be concluded that age and the onset of methane production affect the fermentation pattern in the caeca of chickens.
To study the possibility of immunization against Cryptosporidium baileyi Current, Upton et Haynes, 1986 with the attenuated anticoccidial vaccine, Paracox™ and oocysts of C. parvum Tyzzer, 1912, chickens were inoculated orally with either 3 x 10’ vaccine oocysts or 8 x I O5 C, baileyi or C. parvum oocysts at 1 week of age. The inoculation with Paracox™ vaccine and C. parvum oocysts was repeated at 2 and 3 weeks of age. Uninfected birds served as controls. All animals with the exception of one uninfected group were challenged orally with either 8 x 105 C. baileyi or 3 x 10s Eimeria tenella Railliet et Lucet, 1891 oocysts at 4 weeks of age. Sera were collected at 4 weeks of age, and were examined by ELISA using C. baileyi antigens. Birds inoculated with C. parvum oocysts did not shed C. parvum oocysts in their faeces, but anticryptosporidial antibodies could be detected in the sera. The total oocyst output of C. parvum inoculated chickens was 17% of that of previously uninfected birds after the oral challenge with C. baileyi. Considering that antibodies play no or only a minor role in resistance to C. baileyi, these results suggest that inoculation of chickens with C. parvum oocysts stimulated also cellular immune response. Based on the relative body weight gain, faecal scores, oocyst output, mortality, and caecal lesions in the birds immunized with Paracox™ vaccine and challenged with E. tenella, the vaccination induced only a moderate protection against the reinfection. The results of crossimmunization of chickens with Eimeria spp. and C. baileyi suggest that attenuated anti-eimerian vaccines do not induce any protection against cryptosporidial infection.
Anticoccidial efficacy of a drug combination containing monensin at 8 p.p.m. plus the new antioxidant duokvin at 120 p.p.m. in the feed was compared with that of monensin alone at the recommended level of 100 p.p.m. against a field isolate of the coccidium Eimeria acervulina Tyzzer, 1929 in a battery study. Both monensin and monensin duokvin combination were effective against E. acervulina when judged by weight gain, feed conversion and faecal scores. There was no significant difference in the chemoprophylactic activity of either treatments. Neither monensin at 100 p.p.m. nor the combination proved effective in terms of oocyst production. In accordance with the earlier findings with E. lenella, the combination seems appropriate for field trials.
The aim of the present experiments was to test two methods of separating myoblasts and fibroblasts (selective plating, differential trypsinization) from chick embryonal skeletal muscle and to compare their characteristics. Ornithine decarboxylase (ODC) activity, the amount of incorporated [3H]leucine into proteins and incorporation of [3H]thymidine into DNA were significantly higher in myoblasts than in fibroblasts separated by selective plating. When comparing myoblasts and fibroblasts separated by differential trypsinization, significantly higher ODC activity and greater incorporation of [3H]leucine into protein, but no incorporation of [3H]thymidine into DNA, were found in myoblasts. Higher ODC activity and greater incorporation of labelled leucine were found in fibroblasts separated by the selective plating than in fibroblasts separated by differential trypsinization. The incorporation of labelled thymidine into DNA was higher in myoblasts separated by selective plating than in myoblasts obtained by differential trypsinization. The method of selective plating appears to be simpler and adequate for obtaining myoblastic and fibroblastic cell cultures with sufficiently low mutual contamination. The method of differential trypsinization involves a more drastic treatment of cells and is more time consuming.