Two 14-day growth trials were performed to assess the effects of Eimeria acervulina infection (duodenal coccidiosis) on the Fe-Zn interrelationship in growing chicks. In the first assay, two levels of Fe (0 and 2000 mg/kg) were added to diets that contained either 0 or 52 mg supplemental Zn (from ZnCO3) per kilogram to establish whether excess Fe would affect Zn status of healthy and coccidial-infected chicks. In the second trial, either 0 or 2000 mg Zn/kg was added to diets containing 0 or 500 mg Fe/kg to determine whether Zn could modify Fe utilization. Based on chick performance as well as plasma Zn concentration, excess dietary Fe did not antagonize Zn in either healthy or E. acervulina-infected chicks. Coccidial infection, however, increased liver Fe and decreased intestinal Fe and hemoglobin concentration. Excess dietary Zn reduced performance and Fe content of tissues in both healthy and infected chicks. Coccidial infection ameliorated the adverse effects of excess Zn on performance and tissue Zn concentration and consequently enhanced Fe status of birds fed 2000 mg Zn/kg. These data suggest that the Fe-Zn interaction is a one-directional phenomenon in the chick, i.e., excess Zn reduces Fe utilization but excess Fe does not antagonize Zn.

A series of studies were conducted to assess the drug sensitivity of 26 coccidial field isolates to the anticoccidial effects of nicarbazin (NIC) and narasin + NIC (NAR + NIC). Isolates were collected from typical broiler farms in the United States from 2003 to 2006, propagated once in the absence of anticoccidial medication, and then used to inoculate broilers that were fed nonmedicated rations or those containing NIC 125 ppm or NAR + NIC 80 ppm. Results of these sensitivity trials indicated that 81% of these coccidial isolates were sensitive to the effects of NIC, but only 22% of these coccidia were controlled by NAR + NIC. Studies conducted to evaluate performance responses to these drugs demonstrated that birds fed NIC gained more weight and utilized feed more efficiently than those receiving NAR + NIC. The results of 2 floor pen tests, conducted to confirm the results of the above sensitivity trials, demonstrated that NIC provided a greater level of protection from coccidiosis than NAR + NIC. Lower lesion scores and improved performance were recorded for birds receiving NIC compared with NAR + NIC. Results of these studies revealed that changes in the susceptibility of Eimeria spp. to the activity of NAR + NIC are evident. These changes appear to be associated with the reduction in ionophore sensitivity that has been documented in most areas of the world.

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1. Two series of studies were conducted to determine the effects of a combination of ground plant material derived from Quillaja saponaria trees and Yucca schidigera plants (QY) as sources of saponin, on performance, productivity, nutrient digestibility and ileal morphology of growing broilers. In each trial, 480 Cobb male birds were allocated equally to 24 pens at one-day-of-age according to body weight 2. The studies consisted of two identical floor pen trials in which performance and nutrient digestibility were assessed and two trials where performance and ileal morphology were determined. In each trial, 0, 250 or 500 ppm QY were included in feed given to the broilers from 1-35 or 1-42 d of age, respectively. Eight (digestibility) or 12 (morphology) randomised replicate pens were used. 3. In the digestibility trials, two birds per pen were moved to metabolism cages at d 21. Excreta was collected for a five-day period (d 21 to 25) for the determination of apparent total tract digestibility of dry and organic matter, fat and ash and nitrogen retention. For intestinal morphology, ileal segments were collected from four birds/pen on d 21 to determine villus height and crypt depth. Performance data were collected in each trial series. 4. Results showed that feeding graded levels of QY produced significant linear improvements in performance and productivity at d 35, and similar linear effects were observed for N retention and all apparent digestibility measurements. Morphology data showed that birds receiving 250 and 500 ppm QY had significantly increased villus height 5. These results indicated that QY exerted a positive influence on the intestinal tract by increasing the absorptive surface and improving nutrient digestibility. These effects were considered to be associated with the performance improvements recorded in both experiments.

The pleuromutilin antibiotic tiamulin (TIA) is known to produce a variety of negative interactive effects when it is administered in combination with several anticoccidial ionophores. A 35-d growth study was performed in cages to evaluate the compatibility of TIA when it was administered concurrently with the poly-ether ionophore anticoccidial semduramicin (SEM). Tiamulin and SEM, both alone and in combination, were administered to 10 replicates of female broilers arranged in a completely randomized block design. Tiamulin was administered in drinking water (250 mg of TIA/kg of water) from d 15 through 19 of the study, whereas SEM was incorporated in feed (25 mg/kg) from placement to the conclusion of the test. Water consumption was determined during the period of concurrent administration of the drugs and weekly measurements of feed intake and bird performance were recorded. In addition, hematocrit, blood cell counts, serum protein, albumin, glucose, uric acid, electrolytes, and activities of several enzymes were determined from blood samples taken at d 35. Results indicated that simultaneous administration of TIA and SEM during the third week of the trial reduced water and feed intake resulting in a temporary growth depression. Feed efficiency was transiently affected during the period of coadministration. However, during the fourth week of the test, negative effects in body weight were not observed for any treatment and feed conversion improved for birds concurrently receiving TIA + SEM. By the termination of the experiment, no adverse effects were observed in final performance for any treatment. Histopathological and hematological parameters were unaffected by treatment at d 35 of the test. These results demonstrated that simultaneous administration of TIA and SEM produced only temporary impairments of water and feed consumption that transiently influenced performance. Neither mortality nor long-term effects on performance variables occurred in broilers.

Two series of experiments were conducted to assess the relative ability of strains of Eimeria acervulina and Eimeria tenella to develop resistance to monensin (MON), nicarbazin (NIC), and the monensin plus nicarbazin combination (MON plus NIC). The studies were designed so that drug concentrations in the selection experiments were increased whenever possible. During selection, E. acervulina increased its reproductive index in the presence of NIC or MON plus NIC, equivalent selection in the presence of MON resulted in only a slight increase in reproductive ability. Eimeria tenella, however, was unable to increase its reproductive capacity to the respective drugs. Sensitivity tests after 60 generations of selection revealed that patterns of resistance development for E. acervulina and E. tenella corresponded with the changes in reproductive indices established in the selection experiments. Thus, results of these tests indicate that E. acervulina possesses the ability to develop resistance to NIC and MON plus NIC. Under essentially the same conditions of selection, E. tenella developed only partial resistance to the respective drugs.

Experiments were performed to investigate the effects of Eimeria acervulina infection (duodenal coccidiosis) on the zinc (Zn)-calcium (Ca)-phytate interrelationship in the chick. Three supplemental levels of Ca (0, .91, and 1.82%), two of Zn (0 or 52 mg/kg), and two of sodium phytate (0 or 1.2%) were evaluated as to their effects when added to completely adequate corn-soybean meal diets. Duodenal coccidiosis was produced by multiple crop inoculations of 4 X 10(5) sporulated E. acervulina oocysts. Calcium supplementation depressed gain and efficiency of feed utilization, while Zn content of tissue and plasma was also lowered. Coccidial infection tended to reduce these values further. The addition of dietary phytate also depressed performance and deposition of Zn in tissue. Both excess dietary Ca and phytate addition to the diet markedly reduced plasma Zn concentration of birds fed corn-soybean meal diets unsupplemented with Zn. Addition of 52 mg/kg Zn, however, prevented excess Ca or phytate from exerting this effect. Parasitized chicks responded markedly with increased gain and gain/feed ratios when 52 mg/kg supplemental Zn was added to a 24% protein corn-soybean meal diet containing 1.82% total dietary Ca. It is evident, therefore, that the Zn-antagonizing effect of excess Ca (in the presence of phytate) is exacerbated by duodenal coccidiosis.

The stomachs and intestinal tracts of 253 raccoons, Procyon lotor, were examined for helminth parasites. Sixteen species of helminths were found including eight trematodes, two cestodes, five nematodes, and one acanthocephalan. Fourteen of these helminths are new geographic records for the state of Tennessee. Multivariate statistical techniques were used to analyze two-state and multistate character sets. Matrices of correlation among characters were computed and the first three principal components were extracted, accounting for 79.7% and 66.5% of the variation in the respective character sets. Three-dimensional projections of Tennessee's eight geographic localities onto two-state and multistate principal components demonstrated that raccoons in western localities were parasitized most heavily by Atriotaenia procyonis. Mesocestoides variabilis, Gnathostoma procyonis, and Pharyngostomoides procyonis. Parallelorchis diglossus, Euparyphium beaveri. Eurytrema procyonis, Euryhelmis squamala, Molineus barbatus, and Macracanthorhynchus ingens were most common to P. lotor from eastern areas.