Effect of the anticoccidial agents halofuginone and monensin when given with growth promoting antibiotics upon the control of coccidiosis in the turkey

Anticoccidial drugs and their effects upon the development of immunity toEimeriainfections in poultry

The long-held view that anticoccidial drugs, to a greater or lesser extent, interfere with the development of immunity to Eimeria species may no longer be correct because few drugs, if any, are capable of preventing some degree of parasite multiplication. Acquisition of immunity is, therefore, a real possibility, providing sufficient parasites are present in the environment. Immunity is an important consideration during the rearing of replacement layers, broiler breeders, turkeys, and gamebirds, but little research has been carried out on the effects of drugs on immunity development in these categories of stock. In recent years, there has been a change in the perception of the significance of immunity in broilers, and some broiler producers have taken this into consideration when designing drug programs for use in the field. Studies in floor pens and the field indicate that broilers given various drug programs can develop immunity when exposed to natural infections but that this process takes time: solid immunity not developing until birds are 6 to 7 weeks of age. This suggests that drugs should not be withdrawn from the feed prematurely since birds may not have had time to develop adequate immunity.

Control of Coccidiosis in Turkeys with Diclazuril and Monensin: Effects upon Performance and Development of Immunity toEimeriaSpecies

The effects of diclazuril and monensin, when included in the feed of turkeys from 0 to 10 wk, upon performance and development of immunity to Eimeria species was investigated. Birds were initially inoculated with a low dose of oocysts of three species of Eimeria at 3, 5, 7, and 9 days of age in order to simulate a natural infection. Weight gain and feed intake from 0 to 6 wk of age was significantly greater in medicated birds compared with those that received no anticoccidial medication. Weight gain and feed intake from 6 to 10 wk was greater in birds that received diclazuril than in unmedicated birds. No differences in performance were evident after drug withdrawal from 10 to 16 wk. Immunity to Eimeria species developed by 10 wk in birds that received no anticoccidial medication but did not develop in those given diclazuril or monensin.

Effects of different concentrations of monensin and monensin withdrawal upon the control of coccidiosis in the turkey

The efficacy of different concentrations of monensin in turkeys exposed to field isolates of Eimeria and the effect of the withdrawal of monensin from their diet were investigated. Results of a battery study indicated that 66 ppm monensin was effective against three species of Eimeria in the turkey. In floor pens in which poults were exposed to infection, use of 59.5, 79.4, and 99.2 ppm monensin resulted in reduced mortality and improved feed conversion at 3 wk of age compared with birds that had received no medication. Poults given 59.5 ppm monensin weighed more and had a better feed conversion at 3 wk than poults given 79.4 or 99.2 ppm monensin, but at 10 wk no differences in the body weight or feed conversion of poults given different concentrations of drug were apparent. At 14 wk (and from 10 to 14 wk), poults that had been given 99.2 ppm monensin had a lower feed intake and weighed less than birds that had been given 59.5 ppm of the drug but there were no significant differences in feed conversion. There was no significant difference in the weight gain or feed conversion of poults from 10 to 14 wk of age whether monensin was present in the feed or had been withdrawn. No evidence of compensatory growth was found in the present study.