Efficacy of Stenorol (halofuginone). III. for the control of coccidiosis in turkeys

A Novel Synthesis of the Efficient Anti-Coccidial Drug Halofuginone Hydrobromide

Background: Halofuginone hydrobromide (1) is recognized as an effective drug against several species of Eimeria (E.) in poultry. In this paper, we describe a convenient and low cost preparation method for the compound, as well as primary validation of its activity. Methods: First, 7-bromo-6-chloroquinazolin-4(3H)-one (2) was prepared from m-chlorotoluene by a conventional process, and then chloroacetone was creatively introduced in two steps. Finally, halofuginone hydrobromide (1) was obtained from 7-bromo-6-chloro-3-(3-cholroacetonyl) quinazolin-4(3H)-one (4) by a four-step reaction sequence including condensation, cyclization, deprotection and isomerization. The structures of the relative intermediates and target compound were characterized by melting point, IR, MS and ¹H-NMR. Besides, the protective effect of compound 1-supplemented chicken diet at doses of 6, 3 and 1.5 mg per 1 kg were evaluated on chickens infected with E. tenella, by reduction in mortality, weight loss, fecal oocyst excretion and gut pathology, respectively. Results: Halofuginone hydrobromide (1) was prepared successfully by and improved and innovative method based on traditional research. Moreover, the synthesized halofuginone hydrobromide significantly exhibited an anti-coccidial property. Conclusions: The fruitful work described in this Communication has resulted in halofuginone hydrobromide, which has a good pharmaceutical development prospects, becoming more available for large-scale production.

Identification of new major histocompatibility complex class II restriction fragment length polymorphisms in a closed experimental line of Beltsville Small White turkeys

Beltsville Small White (BSW) turkeys have been utilized as an experimental model in the study of bacterial, parasitic, and fungal diseases. Given the critical role of MHC antigens in the initial steps of the immune response to specific pathogens, the MHC Class II of BSW turkeys was characterized. Southern blot analysis of PvuII-digested turkey DNA that was hybridized with a chicken Class II beta gene genomic clone revealed two restriction fragment length polymorphism profiles not previously identified in experimental or commercial breeder lines of turkeys. These fingerprint profiles differed in a single 6.0-kb band that was present in approximately 38% of the birds examined. The DNA fragments of 5.0, 4.1, 3.3, and 3.1 were present in both profiles. Furthermore, no mixed lymphocyte reaction was observed between individuals within the BSW turkey line. The present results indicate that BSW turkeys represent a unique source of genetic diversity for MHC Class II haplotypes.

Efficacy of different anticoccidials against experimental coccidiosis in large white turkeys

Two trials were conducted to compare the efficacy of currently approved anticoccidials for turkeys against challenge using a field isolate of mixed Eimeria species; E. adenoides, E. gallopavonis, and E. meleagrimitis. Poults in wire-floored cages were fed unmedicated diets from day-old to 3 wk of age. Diets were supplemented with either amprolium (AMP, 125 mg/kg), butynorate (BUT, 375 mg/kg), monensin (MON-60, 60 mg/kg; MON-100, 100 mg/kg), halofuginone (HAL; 3 mg/kg), zoalene (ZOA; 125 mg/kg), or sulfadimethoxine plus ormetoprim (SUL + ORM, 62.5 mg/kg and 37.5 mg/kg, respectively). After 2 days on the test diets, poults were individually weighed and inoculated with sporulated coccidial oocysts from the field isolate. Total fecal collections were obtained for Days 0 to 5 and 6 to 10 to estimate oocyst output. At 10 days postinoculation, the birds were individually weighed and killed to determine severity of intestinal lesions. The HAL and MON were most effective and AMP, ZOA, and SUL + ORM were least effective in maintaining weight and in reducing the severity of intestinal lesions. All the coccidiostats tested reduced oocyst passage, but poults fed HAL produced fewer oocysts. The results demonstrated differences in efficacy among anticoccidials with the more recently approved drugs providing the best protection against coccidiosis.

Effects of different coccidiostats on performance of large white turkeys

Two trials were conducted to evaluate the effects of feeding various anticoccidial products to turkeys to 8 wk and then growing to market age (16 wk for hens and 20 wk for toms). Anticoccidials evaluated in the first trial included amprolium at 187.5 mg/kg for 0 to 4 wk and 125 mg/kg for 4 to 8 wk; butynorate at 375 mg/kg for 0 to 8 wk; monensin at both 60 (MON-60) and 100 mg/kg for 0 to 8 wk; zoalene at 187.5 mg/kg for 0 to 4 wk and 125 mg/kg for 4 to 8 wk; and halofuginone at 3 mg/kg for 0 to 8 wk. In the second trial, MON-60 was replaced by a combination of sulfadimethoxine (62.5 mg/kg) plus ormetoprim (37.5 mg/kg) for 0 to 8 wk. In each trial each treatment was fed to four pens of 16 hens and four pens of 12 toms. Several of the anticoccidials significantly influenced the weight of both hens and toms by producing lower weights at the end of the 8-wk feeding period than birds in other treatments. However, after removal of the anticoccidials, compensatory gains were observed in almost every instance. Significant effects of previous anticoccidial feeding were noted on body weight of hens at 16 wk but not on weights of toms at 20 wk.

Efficacy of halofuginone as a coccidiostat for turkeys

Large White male turkeys were raised to 20 wk of age on diets with varying kinds and levels of coccidiosis drug protection. Dietary treatments included unmedicated control (UMC), amprolium (AMP, 125 mg/kg), and 3 levels of halofuginone hydrobromide (HAL, during 0 to 4 and 4 to 8 wk of age, in 3.3; 3.1.5; and 1.5,1.5 mg/kg, respectively). Turkeys on these five treatments were exposed to coccidial oocysts at 14 days of age and again at 61 days of age; turkeys in an identical five treatments were not exposed until 61 days of age. At 28 days, nonexposed turkeys gained well and similarly, whereas exposed UMC showed poor growth and high mortality. At 56 days, regardless of exposure, UMC were lightest, AMP birds were intermediate, and birds in all HAL treatments were heaviest. Similarities in results of exposed and nonexposed birds suggests that nonexposed birds became exposed through tracking of oocysts in the room. Lesion scores of those challenged with oocysts at 61 days showed that all treatments had adequate resistance to coccidiosis. At 20 weeks of age, combining both exposure methods, birds fed HAL (dosage 3.1.5 or 1.5, 1.5 mg/kg) were significantly heavier than UMC and AMP treatments.

Anticoccidial efficacy of halofuginone in turkeys reared to market weight

Floor-pen studies were conducted in three geographic locations to study the efficacy of halofuginone (3.0 ppm in feed) against important species of coccidia in turkeys. Severe coccidiosis exposure was obtained in studies in Georgia and Colorado and mild coccidiosis in Wisconsin. Coccidiosis caused by contamination of the feed with oocysts of Eimeria adenoeides, E. meleagrimitis, and E. gallopavonis was almost completely controlled by halofuginone at 3 ppm, even though intestinal lesion scores and weight loss were high in two studies. Halofuginone was also highly effective in preventing buildup of infection in pens contaminated by indirect means (movement by caretakers through the pens, etc.). Weight gains and feed conversion were best in poults receiving halofuginone, whether directly or indirectly exposed. There was no evidence that halofuginone caused any untoward reactions in the poults, even though the drug was fed until turkeys reached market weight.

Halofuginone: laboratory titration of anticoccidial activity in young turkeys

Halofuginone was tested at 0, 1.5, 3.0, or 6.0 ppm in the feed against single and mixed infections of recent field isolates of Eimeria adenoeides, E. meleagrimitis, and E. gallopavonis. Severe infections were produced in unmedicated, infected controls. Weight gains were significantly improved by 1.5 or 3 ppm of halofuginone, and intestinal lesion scores and fecal droppings scores were greatly reduced. Oocyst shedding was reduced 91 to 100% by halofuginone treatments. Treatment with 6 ppm of halofuginone gave good protection but appeared to depress weight gains slightly. Treatment with 3 ppm was optimal for the control of all species of coccidia and for optimum performance.

The use of bambermycins (Flavomycin) and halofuginone (Stenorol) in diets for growing turkeys

Experiments were conducted at three geographic locations in the United States (Arkansas, Colorado, and Minnesota) to examine the response of Large White turkeys to bambermycins in the presence of halofuginone. Each location utilized diets commonly used at that station for growing turkeys. All diets contained 3 ppm halofuginone, and were supplemented with 0, 1, 2, or 4 g bambermycins/ton (908 kg). Bambermycins was fed from day-old to marketing; halofuginone was removed from feed for 3 days prior to marketing. Although there were some significant differences in final body weights or feed utilization among locations, there were no significant interactions of location X bambermycins. Body weight of males was significantly (P less than .05) improved by the addition of 2 g bambermycins/ton. Body weight of females was significantly (P less than .05) improved by all levels of bambermycins; 4 g/ton stimulated significantly (P less than .05) superior gains than 1 or 2 g/ton. When body weight for both sexes was combined, bambermycins at 2 and 4 g/ton resulted in significant (P less than .05) improvements in body weight. Feed utilization, expressed as units of feed per unit of gain, was not significantly influenced by dietary treatment. There were no significant differences in mortality related to location or dietary treatment.