The chemoprophylactic effects of halofuginone lactate were tested against calf experimental cryptosporidiosis. Twenty 2-day-old calves, divided into four groups, were orally inoculated with 1 x 10(6) oocysts of Cryptosporidium parvum. The infected control group was unmedicated whereas the three other groups were medicated with the drug at 30, 60 and 120 micrograms kg-1 day-1, respectively, for 7 days, from Day (D) 2 to D8 post-inoculation (D 0 was inoculation day). The calves were weighed twice weekly and disease development and drug efficacy were assessed daily from D0 to D30 from consistency of feces, shedding of oocysts and mortality. Experimental C. parvum infection caused a severe clinical disease with profuse watery diarrhea, high oocyst shedding and mortality (3 out of 5) in the unmedicated group. The results clearly demonstrated the efficacy of halofuginone lactate in reducing the severity of clinical cryptosporidiosis. This efficacy was dose-dependent. The lowest dose (30 micrograms kg-1 day-1) was not able to prevent clinical disease and mortality (3 out of 5). No clinical signs were observed with the 60 and 120 micrograms kg-1 day-1 doses, but the animals shed oocysts after drug withdrawal. This shedding was more delayed the higher the dose of drug administered, but the delayed shedding had no effect on the growth of the animals.

No abstract

SUMMARYIn a survey of chicken coccidia in France during 1994, samples of litter were collected from 41 farms. On 31 of these farms, eimerian oocysts were abundant enough to allow monitoring of their numbers in the litter. Peak total oocyst counts on these farms ranged from 16,200 to 1,254,000/g of litter, but no coccidiosis was observed. The chickens reared without anticoccidial agents in their food (poulets biologiques) produced higher and earlier peak oocyst counts in litter than the chickens given medicated food (poulets labels). The oocysts in litter samples from 22 farms (13 poulet biologique, five poulet label, two standard broiler, one breeder and one layer) of the original 41 were identified. Six of the seven eimerian species known to parasitize chickens were found, using combinations of five methods (oocyst morphology, intestinal lesions, enzyme electrophoresis, growth in embryonating eggs and prepatent time). Multispecific infections predominated (95% of 22 farms), up to six species occurring together. Of farms where oocysts were detected, the percentages with each species were: Eimeria acervulina (100%), E. mitis (82%), E. tenella (77%), E. maxima (73%), E. praecox (45%) and E. brunetti (27%). These appear to be the first definite records of E. mitis and E. praecox for France. Although E. necatrix was not found in this survey, it had recently been detected by other workers in France, so that all seven chicken Eimeria species were known to be contemporaneous.

Fecal and serum anti-Cryptosporidium parvum immunoglobulin A (IgA), IgM, and IgG were monitored by an enzyme-linked immunosorbent assay after experimental and natural infection of calves with C. parvum. Although all experimentally infected calves showed high levels of colostral antibodies in the feces, they acquired C. parnum infection. Three of five animals died. Calves which acquired natural infection showed only diarrhea. Levels of colostral coproantibodies dropped quickly. Experimental infection was followed by a rise in local anti-C. parvum IgM levels from day 5 postinfection (p.i.). IgM peaked at day 14 p.i. and then disappeared quickly. Anti-C. parvum IgA levels rose between days 7 and 14 p.i. and decreased slowly. Rising levels of coproantibodies coincided with falling oocyst output. Fecal anti-C. parvum IgG levels rose slightly during oocyst output, and IgG disappeared 3 weeks p.i. Similar kinetics were established in naturally infected calves. Although fecal anti-C. parvum IgA levels declined slowly, reinfections were established 5, 7, and 14 weeks after the primary contact. Serum anti-C. parvum IgG levels rose during maximal oocyst excretion, whereas serum anti-C. parvum IgA levels peaked later than did local IgA levels. Challenge reinfection of naturally infected calves at day 112 was not followed by clinical signs or oocyst output or by a secondary antibody response. Sequential Western immunoblotting with fecal extracts revealed up to 32 different parasite antigens. Convalescent-phase sera recognized up to 23 antigens. Fecal IgA reacted intensely with antigens with relative molecular weights (Mr) of approximately 11,000 and 15,000. These antigens were not recognized by convalescent-phase serum IgG. Both local IgA and serum IgG also showed strong reactions with 23,000and 44,000-M, antigens and with several antigens of between 66,200 and 200,000 Mr. Most bands remained detectable for at least 16 weeks p.i. Cryptosporidium parvum is a parasite distributed worldwide. It causes diarrhea and sometimes mortality in a broad range of mammals. In calves, the economic impact of cryptosporidiosis is considerable and comparable to that of rotavirus infection (23). C. parvum has been identified as the second most common infectious agent in outbreaks of diarrhea (1, 16). C. parvum is non-host specific and can easily be transmitted from one species to another. Infected calves and

No abstract

No abstract

No abstract

Salinomycin (Coxistac) was tested for efficacy in broilers reared in floor pens at 60 and 80 ppm fed continuously from 1 to 56 days of age. One trial was conducted. Comparisons were made with unmedicated, infected and medicated, noninfected treatments (controls) in addition to infected treatments given either monensin at 100 ppm or halofuginone at 3 ppm continuously (days 1 to 56) in the feed. Coccidia exposure was obtained by infection via the feed. Salinomycin was highly efficacious at 60 ppm based upon improved performance, lesion score, hematocrit, and serum optical density compared with the unmedicated, infected group. Statistical analysis of main effects on weight gain, feed conversion ratio, hematocrit value, and serum optical density showed no significant differences between salinomycin, monensin, or halofuginone. The weight gain of birds given salinomycin at 80 ppm was depressed significantly (P less than .01) at 56 days as a result of decreased feed consumption.