Effects of experimental cryptosporidium infection on broiler chick performance

Experimental infection by the protozoan Cryptosporidium meleagridis was stu died for its effects on broiler chick performance. 120 straight-run chicks of ROSS 208 hybrid were included in a feeding trial. Chicks were divided in to six groups of 20 birds each. Group I was control, groups 2-6, were exper imental ones. Experimental groups were per:orally infected by oocysts of C. meleagridis at a dose 5.10(5) oocysts per chick; group 2 was infected at 7 days of age, group 3 at 14 days, group 4 at 21 days, group 5 at 28 days an d group 6 at 32 days of age. Chicks were housed in littered boxes. External environmental conditions complied with general requirements. Chicks receiv ed commercial feed mixtures - BR I mix till 21 days of age and BR II mix ti ll 42 days of age. The feed mixtures did not contain any anticoccidial drug s. Growth data (Tab. II) show that chick growth in experimental groups was slower on days 7-10 after C. meleagridis infection in comparison with contr ol group. Growth retardation of group 6, infected at 32 days of age, follow ing experimental infection was reflected in the significantly lowest live w eight at the end of feeding (Tab. III). Feed consumption was also negativel y influenced by experimental infection. Higher feed consumption per bird/da y was recorded in experimental groups in all cases two weeks after infectio n (Tab. IV). Chick mortality in experimental groups was lower than in contr ol group (Tab. If). Parasitological examinations indicated that a prepatent period lasted 2-3 days, a patent one 10-14 days in groups 2-5. Experimenta l results show that C, meleagridis infection can negatively influence growt h rate at a definite stage.