Efficacy evaluation of lasalocid plus roxarsone combination medication with different geographic field strains of Eimeria acervulina.

Performance of broiler chickens medicated with lasalocid alone (at 125 ppm) or in combination with roxarsone (at 50 ppm) was evaluated in battery and floorpen trials after challenge with geographically different field strains of coccidia containing predominately the upper intestinal species Eimeria acervulina. No significant difference in bird performance measured at 6 days postinfection (PI) was observed between lasalocid plus roxarsone-medicated (L+RM) or lasalocid-medicated (LM) birds challenged in separate battery trials with mixed-species inocula from Alabama or Georgia containing 92% or 88% E. acervulina, respectively. In contrast, L+RM birds challenged in another battery trial with a Louisiana mixed-species inoculum containing 92% E. acervulina showed significant reduction in average weight gain at 6 days PI compared with LM-challenged birds. A floorpen trial done with the same Louisiana inoculum showed significant reduction in average bird weight gain at 27 and 35 days of age (6 and 14 days PI) for L+RM-challenged birds compared with both unmedicated-nonchallenged (UMNC) control and LM-challenged birds. The LM+R groups were significantly lower in average bird weight at 27 days of age than the unmedicated-challenged controls. Feed conversions (FCs) for L+RM birds were significantly higher than those for the UMNC control birds during time of challenge (21-27 days of age) and for the 1-to-27-day-of-age time period. No significant difference in FC was seen between the UMNC and LM groups. Results of this study showed that performance of broiler birds medicated with lasalocid plus roxarsone could vary for geographically different mixed-species challenge inocula that contained predominately E. acervulina.

Rofenaid in the control of Pasteurella anatipestifer and Escherichia coli infections in ducklings.

In a series of controlled battery trials, Rofenaid (at doses ranging from 0.02 to 0.12% active drug in feed) was administered to ducklings infected experimentally with Pasteurella anatipestifer and Escherichia coli strains. Against P. anatipestifer, Rofenaid at 0.02 to 0.12% levels in feed either prevented or reduced mortality, gross lesions, and bacterial isolations. Furthermore, the weight gain and feed conversion of infected Rofenaid-medicated ducklings were superior to those of uninfected unmedicated controls in two out of three trials. Against E. coli, Rofenaid at 0.02 to 0.08% levels in feed either prevented or reduced mortality, gross lesions, and bacterial isolations. Weight gain and feed conversion of infected Rofenaid-medicated ducklings were also superior to those of uninfected unmedicated controls in two out of three trials. It appears that Rofenaid, at a 0.02-0.08% level, controls infections in ducklings caused by P. anatipestifer and E. coli strains sensitive to this compound.

Lasalocid: resistance and cross-resistance studies in Eimeria tenella-infected chicks.

Eimeria tenella was passaged in the presence of suboptimal and optimal concentrations of lasalocid (X-537A, sodium salt) in feed. Lasalocid was equally active at concentrations of 0.006 and 0.0075% against the 10th and 15th passage of E. tenella lasalocid exposed strains. Resistance to lasalocid could not be induced. Lasalocid administered in the feed at 0.0075% was tested in controlled battery experiments against E. tenella strains resistant to known anticoccidials in chicks. These studies demonstrated that lasalocis, at the optimal feed concentration of 0.0075% was highly effective against coccidiosis induced by strains of E. tenella resistant to sulfaquinoxaline, nicarbazine, zoalene, emprolium, clopidol and 4-hydroxyquinoline. Lasalocid medicated chicks were heavier, converted feed more efficiently, showed less pathologic lesions, and had lower mortality (P less than or equal to .05) than the infected unmedicated controls as well as sulfaquinoxaline, nicarbazine, zoalene, amprolium-ethopabate, clopidol, buquinolate, decoquinate and nequinate medicated groups. Cross-resistance to lasalocid was not demonstrated.

Lasalocid in prevention of turkey coccidiosis.

Lasalocid was tested at graded feed concentrations in controlled battery experiments against single and mixed Eimeria species infections in 2-week-old turykey poults. Eimeria meleagrimitis, E. gallopavonis, E. adenoeides, and E. dispersa infected poults medicated with lasalocid at concentrations of 0.15, .0125, .01, .0075, and .005% were heavier, converted feed more efficiently, showed lower lesion scores (ADI), shed fewer oocysts, and showed reduced or no mortality as compared to the infected, unmedicated controls. Lasalocid activity was similar against the few field isolates tested. Lasalocid responses were dose related, the higher the concentration, the greater the effect. The optimum dose level in these battery studies was approximately .0125%. Lasalocid fed at two times the optimum dose level to poults for a four week period did not have any adverse effect on growth or feed conversion performance.

Effects of lasalocid (.0125%) in combination with roxarsone on lesion reduction and oocyst suppression in chickens infected with Eimeria tenella field isolates.

Lasalocid (.0125%) alone and combined with roxarsone (.005%) was evaluated for its effect on lesion reduction and oocyst suppression in thirty-five controlled replicated battery experiments, using in excess of 6200 broiler chickens. The chickens were inoculated with field isolates containing predominantly Eimeria tenella species. Lasalocid (.0125%) used alone exhibited a high degree of anticoccidial activity. Lasalocid (.0125%) fed in combination with roxarsone (.005%) showed, in addition to high anticoccidial activity, a further reduction in gross lesion (P less than .01) and oocyst production (P less than .05) over lassalocid used alone.

Compatibility and anticoccidial activity of lasalocid in combination with roxarsone and antibiotics against Eimeria mixed infection in chicks.

Lasalocid at the concentration of .0075% (68 g/ton) with and without roxarsone 45.4 g/ton was fed in combination with the growth promotants bacitracin methylene disalicylate 200 g/ton, bambermycins 2 g/ton, lincomycin 4 g/ton, nosiheptide 2.5 g/ton, zinc bacitracin 200 g/ton g/ton, and virginiamycin 20 g/ton exhibited a high degree of anticoccidial activity against mixed Eimeria infection in chickens in 9 day challenged battery trials. In these short term challenge trials chicks fed lasalocid, and the lasalocid growth promotant combinations, performed significantly better (P < .05) for growth and anticoccidial efficacy than those fed the growth promotants alone, and the infected, unmedicated controls. In almost all instances, the lasalocid-roxarsone-antibiotic combinations allowed for numerical increases in gains, improvement in feed conversion, and numerical decreases in lesions (in some cases, statistically significant (P < .05) over chicks fed lasalocid alone and/or the lasalocid antibiotic combination. The growth promotants did not interfere with the anticoccidial activity of lasalocid. The growth promotants fed alone exhibited no anticoccidial activity. However, when roxarsone was combined with the antibiotics, the combination resulted in numerically improved performance, reduced mortality, and in most instances, statistically significant decreases in lesions (P .05) over the infected, unmedicated control.

The effect of vitamins A, E and K on experimentally induced histomoniasis in turkeys.

Vitamins A, E and K were incorporated into turkey starter rations at normal (1 x ), 5 x and 50 x the National Research Council recommended vitamin levels and evaluated for their effect on histomoniasis in turkeys. Infected as well as comparable unifected poults were included in all trials. Each vitamin was also evaluated at normal and 50 x the NRC level in combination with ipronidazole, a low-level antihistomonal agent. In addition to performance parameters, glutamate oxaloacetate transaminase (GOT) and lactate dehydrogenase (LDH) plasma enzyme levels were used to evaluate the vitamin effect. None of the vitamins tested alone were found to be effective in terms of reducing mortality and morbidity following a severe Histomonas meleagridis challenge, regardless of the vitamin dose. A significant improvement in performance was demonstrated with the vitamin E (50 X)--ipronidazole combination and a numerical improvement with the vitamin A (50 X)--ipronidazole combination over ipronidazole alone or the poults fed NRC recommended vitamin levels. The GOT and LDH plasma enzyme levels correlated well with the progressive pathological changes associated with the disease. At 11 days post-infection both enzymes were consistently and significantly elevated above those of the uninfected controls, irrespective of the vitamin levels provided. The presence of low ipronidazole in most instances delayed the onset of clinical symptoms and was associated with a delay in enzyme elevation, indicating the excellent correlation and sensitivity of the enzyme method in assessing liver damage.

Antiparasitic activity of natural and semisynthetic monensin urethanes.

A total of 17 monensin urethanes, including two naturally produced phenethylurethanes (Streptomyces sp.), were evaluated for antiparasitic activity. All of the compounds had the characteristic properties of the polyether antibiotics including their ability to transport cations across membranes. Several of the semisynthetic derivatives demonstrated in vitro and in vivo anticoccidial activity in chickens. In vitro activity was shown utilizing chick kidney cell culture experimental procedures in which several of the semisynthetic antibiotics were active at 1 ppm or less. Derivatives having anticoccidial efficacy exhibited activity in vitro against Treponema hyodysenteriae, the causative agent of swine dysentery. Mice previously treated with specific semisynthetic urethanes survived a severe Plasmodium berghei challenge indicative of antimalarial properties as well. Specific biological activity could be correlated with structural relationships of the semisynthetic urethanes.