Field Experience Trials Comparing Narasin and Monensin

Abstract

Narasin is effective against all species of chicken coccidia when tested in battery cage and floor pen studies. To confirm the efficacy of narasin under practical broiler production conditions, the drug was fed at concentrations of 60 ppm or 80 ppm to broiler chickens being raised by six different commercial broiler producers in five different geographic areas. Monensin was fed in each trial at a concentration of 100 ppm or 121 ppm as a reference control. The usual management practices of each of the integrated broiler companies were followed throughout the respective trials. Nine trials were conducted and approximately 100,000 broilers were tested for each treatment. No adverse reactions attributable to treatments were observed in any of the trials, and performance results obtained with narasin-medicated birds were generally comparable with those obtained with monensin-medicated birds in the same trial. These findings support the conclusion that narasin at final feed concentrations in the range of 60 to 80 ppm can be safely and effectively used as an anticoccidial agent in commercial broiler production facilities.

Forty years of monensin for the control of coccidiosis in poultry

“…MacPherson (1978) showed that at 3 farms, broilers given monensin had improved live weights and reduced feed conversion ratios, mortality, and lesions compared with those given an amprolium combination. Jeffers et al (1988) found that in 9 field trials, birds receiving monensin (100 or 121 mg/kg) had lower BW than birds given narasin (80 mg/kg), but feed conversions were similar with both drugs. In commercial broilers, a change to monensin from an amprolium combination resulted in an improvement in feed conversion and was accompanied by a marked reduction in the level of infection, judged by the numbers of oocysts in the litter, an effect still evident after 11 flocks (Long et al, 1975).…”

The impact of Bacillus subtilis DSM 32315 on the pathology, performance, and intestinal microbiome of broiler chickens in a necrotic enteritis challenge

“…The effectiveness of Narasin is in line with the literature as strains of both Eimeria spp. (Ruff et al, 1979; Jeffers, 1981; Jeffers et al, 1988; Smith and Strout, 1980; Weppelman et al, 1977) and C. perfringens (Elwinger et al, 1992; Watkins et al, 1997; Elwinger et al, 1998; Martel et al, 2004; Bafundo et al, 2008; Silva et al, 2009) have been observed to be susceptible to the ionophore. However, numerous studies also report Narasin resistance in field strains of Eimeria spp.…”

Thomas K. Jeffers: pioneer of coccidiosis research

“…Extensive battery and floor-pen studies were conducted that demonstrated the efficacy of narasin (Jeffers et al, 1988a, b). Field trials showed that performance results with narasin-medicated birds were comparable with those of birds given monensin (Jeffers et al, 1988c). No adverse reactions attributable to treatment were found.…”