Coccidiostat

Abstract: Methyl 7-diethylamino-4-hydroxy-6-n-propylquinoline-3-carboxylate, amquinolate, initially showed great promise as a broad-spectrum anticoccidial agent in extensive evaluation studies against 120 laboratory and field strains of coccidia. Subsequently, further tests were conducted with 12 field strains obtained from commercial poultry farms where a related quinoline coccidiostat reportedly had failed to control coccidiosis. The 12 strains were resistant to four new quinoline coccidiostats: amquinolate, buquinolate, MB 1968). As part of an extensive study of this compound we tested it against 120 strains of coccidia. Of these, 24 strains (representing 8 species of Eimeria) had been propogated from single oocysts that had previously been isolated from field cultures. The remainder were field strains from widely separated geographical areas; they included various species of Eimeria and had been implicated in clinical coccidiosis. Amquinolate, at a concentration of 0.003% in the diet, was fully effective against 111 (92%) of the strains; and a combination of 0.003% amquinolate and 0.01% amprolium was effective against 120 (100%) of them. Upon completion of this series of tests, 12 field cultures were received from commercial poultry facilities in which another quinoline coccidiostat had allegedly failed to give satisfactory control of coccidiosis. It was considered of special interest to test several quinoline coccidiostats against these strains to determine if drug resistance was involved, and if so, to determine whether the strains were resistant to more than one quinoline compound. This paper reports the results of these tests, together with the results of tests designed to induce resistance to amquinolate by means of exposure to the drug under laboratory conditions. MATERIALS AND METHODS For measurement of anticoccidial effects of drugs, 2-week-old sexand weight-balanced "whitecross" chicks in groups of 10 were fed a standard Received for publication 9 August 1968. laboratory ration to which drugs were added just prior to use. The uninfected and infected control birds were fed the basal ration. On the second day of the test the chicks were inoculated orally with sporulated oocysts. The number of oocysts given per bird depended upon the species being used in a given test as follows: E. tenella, 50,000; E. necatrix, 50,000; E. brunetti, 100,000; E. maxima, 100,000; E. acervulina type, 200,000; mixed cultures, 200,000 to 250,000. Several criteria were employed for evaluation of efficacy of a drug. These included observations and records on the mortality rate, growth, severity of pathological lesions, and number of oocysts produced. Coccidial lesions were scored according to the following system: 0 = normal, 1 = detectable, 2 = moderate, 3 = marked, 4 = maximal. To obtain estimates of oocyst production, intestinal tissue or fecal material was homogenized in a blender. Appropriate aliquots were diluted, placed in a hemacytometer, and counted. For each group of birds all of these criteria were combined to yield a single criterion of efficacythe "anticoccidial index." This number indicates the overall relative anticoccidial activity of the agent tested in each group of birds. The anticoccidial index is the sum of (1) the per cent survival of the birds plus (2) the per cent relative weight gain minus (3) the lesion index, and minus (4) the oocyst index. Each component of the anticoccidial index for a group of chicks is computed as follows: (1) The per cent survival (0-100%) contributes the corresponding number of points (0-100). (2) The per cent relative weight gain, calculated by comparing the average weight gain of the group to the average weight gain (as 100%) of the noninfected nonmedicated group, contributes the corresponding number of points (0-100, or more or less). (3) The observed average coccidiosis lesion score (04.0) is multiplied by 10 to become the corresponding assigned lesion index (0-40). (4) The observed number of millions of oocysts per bird ( 40) is (a) in the case of infections with intestinal species, compared to the oocyst count (as 100%) for the infected nonmedicated control group to obtain an "observed per cent of

Abstract: SUMMARY A trial was conducted to assess the effects of the dietary supplement Yucca schidigera extract on the performance of broilers subjected to different coccidiosis control methods. Six hundred male broiler chicks were randomly allocated to 1 of 5 treatments with 4 replicates each. The treatments were as follows: T1, vaccinated against coccidiosis; T2, nonvaccinated, a dietary coccidiostat; T3, vaccinated against coccidiosis, diet supplemented with Y. schidigera extract (0.01%); T4, coccidiostat plus Y. schidigera extract added to feed (0.01%); and T5, nonvaccinated, nonsupplemented control. The parameters analyzed were bird performance and morphology of the intestinal mucosal surface. The intestinal villi were higher a t6do f age inbroilers treated with coccidiostats or vaccinated against coccidiosis and supplemented with Y. schidigera extract compared with groups receiving the vaccine only or no treatment. Addition of the Y. schidigera extract to the diet of vaccinated birds improved average daily gain and feed conversion rate at 42 d of age compared with the other treatments, suggesting there might be a beneficial, synergistic effect between the coccidiosis vaccine and the Y. schidigera extract.

Abstract: This study was conducted to examine the effect of feeding a botanical probiotic (Feed FreeTM) containing Lactobacillus on growth performance of broiler chickens from 1 to 42 d of age. At 56 d, five broilers per pen were killed and processed to determine bacteria populations in the ceca, cloaca, and carcass rinse. The dietary treatments were the basal diet with coccidiostat and antibiotic (control), basal diet without coccidiostat and antibiotic (negative control) and basal diet supplemented with 0.10% probiotic. The results showed that body weights and average weight gain were not different (P > 0.05) due to treatment. Feed intake and feed to gain ratio from 22 to 42 d of age were lower (P < 0.001) for broilers fed 0.10% probiotic than broilers fed the control diets. The population of Lactobacilli recovered from cloaca contents was higher (P < 0.002) and the population of Clostridium perfringens recovered from cloaca contents was lower (P < 0.02) for broilers fed the 0.10% probiotic diet than for those fed the control diets. The population C. jejuni recovered from carcass rinses for broilers fed the diet supplemented with the probiotic tended (P < 0.11) to be lower when compared to the negative control. These results suggest that diets supplemented with the botanical probiotic containing Lactobacillus supports growth for broilers similar to the basal diet supplemented with antibiotic and coccidiostat, and with lower feed to gain ratio. Also, the botanical probiotic may reduce C. perfringens and C. jejuni in market-age broilers.