Effects of nicarbazin on the blood glucose and liver glycogen statuses of male broilers.

Nicarbazin (NCZ), an effective anticoccidial widely used by the global broiler industry, is known to produce some side effects in broilers. Recent field observations have suggested that NCZ could be associated with spiking mortality syndrome, a disease of uncertain etiology that is most commonly characterized by hypoglycemia. In turn, 2 trials were conducted to investigate the effects of NCZ on the blood glucose levels and liver glycogen content of Ross × Ross 708 male broilers. In 6 of 12 pens beginning at 1 d of age, NCZ was added to basal broiler diets at a rate of 125 mg/kg, and the other 6 pens were control pens in which birds received salinomycin instead of NCZ, at a rate of 66 mg/kg. Feed and water were provided ad libitum, feed was closely monitored in all pens to avoid shortages, no coccidial challenge was imposed, and room temperature never exceeded 29.4°C. At the end of the second trial, a photoperiod increase from 8L:16D to 24L:0D was imposed in an effort to induce stress due to feed engorgement. In response to NCZ in trial 1, 0 to 28 d feed conversion and relative liver weights on d 21 and 28 were higher, whereas 0 to 28 d cumulative BW gain was lower. In response to NCZ in trial 2, 0 to 13 d feed conversion was higher, whereas 0 to 13 d cumulative BW gain was lower. The added NCZ increased blood glucose on d 13 in trial 2, but did not affect at any time the liver constituents analyzed in both trials. In conclusion, the uninterrupted feeding of NCZ at 125 mg/kg in the starter and grower diets of male Ross × Ross 708 broilers increased feed conversion and reduced BW gain, but despite an increase in relative liver weight on d 21 and 28 posthatch, liver glucose and glycogen concentrations were not affected.