Effect of Supplemental Levels of Calcium and Zinc on Energy Metabolizability and Nitrogen Retention in Broilers Exposed to Mixed Coccidiosis

Three hundred six, day-old broiler chicks were randomly divided into 24 groups of 12 to 13 chicks in each group. Six isonitrogenous and isovaleric dietary treatments were formulated using two levels of calcium (1.03 and 1.98%) and three levels of zinc (63,93 and 123 ppm) in a 2x3 factorial design. Each dietary treatment was offered to four replicated groups. After four weeks of age, two groups under each treatment were artificially infected with 60,000 sporulated oocyst of mixed coccidial species (Eimeriatenella, E. acervulina and E. necatrix) through crop incubation method. Two metabolism trials were conducted during 4–6 (the acute stage) and 10-12d (the convalescence stage) of post-infection period. DM metaboltzability decreased (P<0.01) during 4-6d post-infection period. Energy metabolizabitity and nitrogen retention (%of intake) were lower (P<0.01.) in infected groups in both the trials. Nitrogen retention decreased (P<0.01) with increased level of Zn in diet in the second trial however it was higher (P<0.01) in high Ca diet in both the trials. The interaction between Ca and infection was significant (P<0.01) and values were higher in infected groups than in those fed low Cadiet. The results indicated that higher level of dietary Ca (1.98%) is beneficial in improving nitrogen retention in birds infected with coccidia.