Broiler Operations Research Articles

Effects of feeding cracked corn and concentrate protein pellets on broiler growth performance

Typically, in a vertically integrated poultry (broiler or turkey) operation, maintaining adequate feed manufacturing production proves to be a challenge. To evaluate an alternative management strategy, 2 studies were conducted to examine the effects of feeding broilers cracked corn and a concentrated pellet on broiler growth performance from 0 to 41 d of age. Cracked corn (0, 25, 50, 75, or 100%) was used to replace the corn fraction in the diet for all 3 stages of growth. Cracked corn and concentrate pellets were blended together to be isonitrogenous and isocaloric among all treatments, so only feed form would differ. Experiment 1 diets included a control (0% cracked corn) and experimental diets (25, 50, 75, or 100%) in which cracked corn directly replaced the ground corn fraction. Overall (0 to 41 d), a linear decrease (P < 0.001) for ADG and ADFI and a linear increase (P < 0.003) for FCR was observed as cracked corn levels increased. In experiment 2, a “step-up” feeding program of cracked corn was evaluated with dietary treatments including the following: 1) control (0% cracked corn throughout feeding), 2) 0% cracked corn (0 to 17 d) and 25% (18 to 41 d), 3) 0% cracked corn (0 to 17 d) and 50% (18 to 41 d), 4) 25% cracked corn (0 to 41 d), and 5) 50% cracked corn (0 to 41 d). Overall (0 to 41 d), ADG for treatment 1, 2, and 4 was greater than 3 and 5 (P < 0.05). Feed conversion ratio was superior for treatments 2 and 4 (P < 0.05) in comparison with treatments 3 and 5. Up to 25% of the dietary corn can be fed to the broiler as cracked corn from 0 to 41 d without a negative response on growth performance.

Determining the Nitrogen Budget and Total Ammoniacal Nitrogen Emissions from Commercial Broilers Grown in Environmental Chambers

SUMMARY One of the undesirable by-products of raising commercial broilers in confinement is the production and release of NH3 into the environment. Ammonia negatively affects flock performance, reduces air quality, increases N deposition into neighboring ecosystems, and reduces plant-available litter N. Animal agriculture is currently under pressure to reduce NH3 emissions. Understanding the fate of N inputs and outputs from commercial broiler operations is important for increasing flock N efficiency and reducing gaseous N emissions. A total directmeasurement N balance trial was conducted on broilers from 0 to 42 d of age with all N inputs and outputs measured. The N inputs included feed and chick N, whereas outputs included broiler N retention, total ammoniacal N (TAN) emissions, mortality N, and litter N accumulation. The major N input was feed N, accounting for 99% of total inputs. After 42 d, the percentage of N input recovered was as follows: 67 ± 2% in live broilers, 26 ± 2% accumulated in the litter, and 13 ± 0.4% in TAN emissions. The average difference between the measured N inputs and outputs was 5 ± 3%, indicating a good N balance. The period from 0 to 21 d of age accounted for 23% of the flock total TAN emissions. The remaining 77% of TAN loss occurred from 22 to 42 d of age, most likely due to greater N excretions in the feces and a rise in litter pH and moisture resulting in greater NH3 production. Daily TAN emissions ranged from 0.13 to 0.78 g of TAN per bird, with a 0 to 42 d mean of 0.37 g of TAN per bird. Total TAN emissions over 42 d averaged 15.3 ± 0.5 g of TAN per bird, which is consistent with other literature values and the high N recovery in the broilers. The TAN emission from a complete broiler cycle, including the emissions for a week interval between flocks, was 17.5 ± 0.5 g of TAN per bird. These results support the view that management practices leading to high broiler N recovery are consistent with lower TAN emissions.

Characteristics of Persistent Salmonella Enteritidis Strains in Two Integrated Broiler Chicken Operations of Korea

The objectives of the study were to investigate the phenotypic and genotypic characterization of the persistent Salmonella Enteritidis (S. Enteritidis) isolates in two integrated broiler chicken operations, with attention focused mainly on the epidemiological approach. In the distribution of virulence genes, Salmonella enterotoxin (stn), invading host cell (invA), and Salmonella plasmid virulence (spvC) genes were widely distributed among the S. Enteritidis irrespective of their source of isolation, and Salmonella fimbrial (sefC) and plasmid encoded fimbrial (pef) genes were present in 28 and 20 S. Enteritidis strains, respectively. A total of 5 different XbaI-PFGE types were obtained from 31 S. Enteritidis isolates. Twenty-one types were divided on the basis their PFGE pattern, phage type and antimicrobial resistance pattern determined. There was a significant difference in phenotypic and genotypic characterization by two integrated broiler operations. Also, 8 isolates shown susceptible to all antimicrobials and 11 isolates with resistance to nalidixic acid were partly classified by XbaI PFGE pattern and by the phage type.

Size fractionated particulate matter emissions from a broiler house in Southern Ontario, Canada

In 1999, the National Emission Inventory and Project Task Group developed particulate matter emission inventories for the Canadian poultry industry using Canadian poultry census data and emission factors for all types of poultry operations based on U.S. Environmental Protection Agency and British Columbia/Greater Vancouver Regional District data [MOE. A Compendium of Knowledge on Fine Particulate Matter in Ontario. Ontario Ministry of the Environment (MOE) Review Report (as released to the CRESTech/NERAM expert panel). PIBS 3798e, 1999.]. Recent studies conducted on various poultry operations suggested that the emission factors currently in use could lead to a substantial underestimation of the airborne PM levels in Canada generated by these poultry industries. This study measured real time PM concentrations and house ventilation rates from a commercial broiler operation in southern Ontario in order to develop characteristic PM emission factors and inventories. The averaged particulate matter emission factors obtained were 0.11+/-0.004, 0.13+/-0.005, and 0.56+/-0.02 kg(PM) (1000 birds)(-1) (production cycle)(-1) for PM(1), PM(2.5), and PM(10), respectively. The yearly emissions for the studied commercial broiler operation were 22, 27, 114 kg(PM) (year)(-1) for PM(1), PM(2.5), and PM(10), respectively. The estimated PM emissions for Canada from the broiler sector are 382.4+/-13.9, 472.7+/-16.3, and 2025+/-69.9 tonnes(PM)/year for PM(1), PM(2.5), and PM(10), respectively.

Characterization of &lt;i&gt;Salmonella&lt;/i&gt; spp. Isolated from an Integrated Broiler Chicken Operation in Korea

The purpose of this study was to investigate the biological and genetic characterization of persistent Salmonella isolates in an integrated broiler chicken operation, in an attempt to elucidate the source of contamination. From the breeder farm, the hatchery, the broiler farm and the chicken slaughter house of an integrated broiler chicken operation, a total of 6 serotypes were observed. Although S. Heidelberg was not detected in the broiler farm, it was consistently found in the breeder farm, the hatchery and the chicken slaughter house. Also, S. Enteritidis and S. Senftenberg were found in the hatchery and the chicken slaughter house, and the hatchery and the broiler farm, respectively. S. Gallinarum and S. Blockley were found only in the broiler farm, and S. Virchow was only recovered in the chicken slaughter house. Isolated S. Heidelberg, S. Enteritidis and S. Senftenberg strains were divided into 3, 5 and 7 types, respectively, on the basis of all properties. Especially, S. Senftenberg isolates, divided into four types by their antimicrobial resistance patterns, were all obviously the XbaI PFGE pattern. Also, four S. Enteritidis isolates resistant to nalidixic acid showed a difference in phage type and PFGE pattern. Such a different pattern was shown despite Salmonella isolates originating from an integrated broiler operation, suggesting that further epidemiological studies on many integrated chicken companies in Korea are needed.

Dissemination and tracking of Salmonella spp. in integrated broiler operation

Controlling Salmonella in integrated broiler operation is complicated because there are numerous potential sources of Salmonella contamination, including chicks, feed, rodents, wild poultry operations, and the processing plant. The objective of this study was to investigate the distribution of Salmonella through all phases of two integrated broiler operations and to determine the key areas related to the control of all known sources of infection. Two different Salmonella serotypes were observed at integrated broiler chicken company A. S. enteritidis, the predominant company A isolate, was consistently found in the breeder farm, hatcheries, broiler farms, and chicken slaughterhouse. At company B, a total of six different serotypes, S. heidelberg, S. senftenberg, S. enteritidis, S. blockley, S. gallinarum, and S. virchow, were detected. Although S. heidelberg was not found in the broiler farms, it was consistently found in the breeder farm, hatcheries, and chicken slaughterhouse. In addition, S. enteritidis was found in the hatcheries, broiler farm, and chicken slaughterhouse. In order to obtain the genetic clonality, 22 S. enteritidis isolates were digested with XbaI and analyzed by pulsed-field gel electrohporesis (PFGE). A difference in the PFGE pattern was found to be related to the origin of the integrated broiler operation. These data support the critical need to control Salmonella in breeder farms and hatcheries, and demonstrate important points related to the control of infection in large-scale poultry operations of Korea.

Vertical transmission of a fluoroquinolone-resistant Escherichia coli within an integrated broiler operation

The epidemiology of an enrofloxacin-resistant Escherichia coli clone was investigated during two separate outbreaks of colibacillosis in the Danish broiler production. In total five flocks were reported affected by the outbreaks. Recorded first-week mortalities were in the range of 1.7–12.7%. The clone was first isolated from dead broilers and subsequently demonstrated in samples from associated hatchers and the parent flock with its embryonated eggs, suggesting a vertical transmission from the parents. The second outbreak involved two broiler flocks unrelated to the affected flocks from the first outbreak. However, the clone could not be demonstrated in the associated parent flock. Furthermore, samplings from grand-parent flocks were negative for the outbreak clone. The clonality was evaluated by plasmid profiling and pulsed-field gel electrophoresis. None of the recognized virulence factors were demonstrated in the outbreak clone by microarray and PCR assay. The molecular background for the fluoroquinolone-resistance was investigated and point mutations in gyrA and parC leading to amino-acid substitutions in quinolone-resistance determining regions of GyrA and ParC were demonstrated. Vertical transmission of enrofloxacin-resistant E. coli from healthy parents resulting in high first-week mortality in the offspring illustrates the potential of the emergence and spreading of fluoroquinolone-resistant bacteria in animal husbandry, even though the use of fluoroquinolones is restricted.

Application of Polymerase Chain Reaction Based on ITS1 rDNA to Speciate Eimeria

A method was developed to recover Eimeria spp. oocysts directly from poultry litter and determine which species of Eimeria were present using polymerase chain reaction (PCR) based on the ITS1 rDNA sequence. The species composition of Eimeria oocysts was also compared before and after propagation in susceptible chickens to determine if the relative proportion of each species changed after expansion. In samples from two broiler operations, ITS1-PCR was able to detect Eimeria spp. oocysts recovered from litter, with Eimeria acervulina, Eimeria maxima, and Eimeria praecox being the predominant species present therein. Although Eimeria tenella was found in one sample, the other species--Eimeria brunetti, Eimeria necatrix, and Eimeria mitis-were not detected. The species composition as determined by ITS1-PCR did not appear to appreciably alter after expansion in susceptible chickens. The described method represents a rapid means for determining the major Eimeria species in a poultry operation and may be helpful in choosing a particular live oocyst vaccine formulation to protect chickens against coccidiosis.

Research Article: Economic and Environmental Assessment of Proactive Phosphorus Control Measures for Broiler Operations

Duck Creek watershed, a small watershed in east-central Texas, experienced an influx of broiler growing operations in the later half of the 1990s. Preliminary results indicated that year 2000 levels of broiler litter land application do not pose a water quality concern but that a significant expansion of broiler production would more than double ambient phosphorus loads in the watershed. Environmental and economic modeling were used to assess the effects of phosphorus control measures designed to proactively mitigate the environmental impacts from further broiler industry expansion. Results of best management practice (BMP) simulations indicate that ambient phosphorus loads from broiler litter can be reduced by reducing the rate of litter application, by hauling off litter, by adding phytase to broiler feed, and by amending broiler litter with aluminum sulfate (alum). Reduced-rate scenarios were substantially more cost-effective than haul-off scenarios. Simulations of the phytase and alum BMPs produced ne...

Fecal bacteria and sex hormones in soil and runoff from cropped watersheds amended with poultry litter

The application of poultry litter to agricultural fields can provide plant nutrients for crops and forage production, but fecal bacteria and the sex hormones estradiol and testosterone are components of litter that can be detrimental to the environment. Our objective was to determine if applications of poultry litter to small watersheds would contribute to the load of fecal bacteria and sex hormones to soil and runoff. We, therefore, investigated the fate and transport of fecal bacteria, estradiol and testosterone from surface applied poultry litter to four small cropped watersheds. Poultry litter was applied to meet the nitrogen requirements of pearl millet ( Pennisetum glaucum L.) in 2000 and grain sorghum [ Sorghum bicolor (L.) Moench] in 2001. Neither Salmonella nor Campylobacter were detected in the litter but the fecal indicator bacteria were. The average load of total coliforms, Escherichia coli, and fecal enterococci applied with the litter was 12.2, 11.9, and 12.7 log 10 cells ha − 1 , respectively. The average load of estradiol and testosterone was 3.1 and 0.09 mg ha − 1 , respectively. Runoff events first occurred 7 months after the first litter application in 2000, and 3 weeks after the second application in 2001. Only for the 25 July 2001 runoff event 3 weeks after the second litter application were the concentrations of total coliforms, E. coli, and fecal enterococci in runoff greater than background concentrations which were on average 5.2, 2.9, and 1.1 log 10 MPN 100 ml − 1 , respectively. Average background levels of total coliforms, fecal enterococci, and E. coli in surface soil were 8.2, 7.9, and 3.5 log 10 cells kg − 1 soil. At the rate of litter application the concentrations of estradiol and testosterone in the litter did not appear to impact the background levels in the soil and runoff. Because concentrations of sex hormones in litter from other broiler operations are known to be greater than in the litter we applied, further study on the connection between concentrations of sex hormones in poultry litter and operational practices is recommended.

Nuisance and Odor Issues in Broiler Production: A Case Study

Recent expansion of the broiler industry in Texas resulted in an opportunity to experience and mitigate a number of nuisance and odor issues related to broiler production. For the sake of this discussion, the participants in these issues are divided into 3 groups: the poultry industry; the nonpoultry citizenry; and government, regulatory, and educational agencies. Establishment of a broiler complex in an area with little exposure to commercial poultry production resulted in a concerned nonpoultry citizenry. This was often exacerbated by misinformation, external influences, and poor communications, resulting in a less-than-optimum level of trust between the nonpoultry citizenry and the poultry industry. Early in the process, the poultry industry attempted to provide information and open communication with the nonpoultry citizenry; however, establishment of bias within the nonpoultry citizenry eroded trust and cooperation to the point that effective communication was difficult. Throughout this period, government, regulatory, and educational agencies were involved in investigations of complaints, facilitation of communication, and development of policy. Over a 2-yr period these activities resulted in a special legislative appropriation to investigate odor and nuisance issues related to broiler production. This investigation and other agency activities resulted in the development of regulatory policy that required all broiler producers to develop comprehensive nutrient management plans. Although these plans are primarily concerned with water quality and environmental issues, the nonpoultry citizenry was willing to accept this step as a means to assure that poultry facilities would be operated in compliance with best management practices. As a result, the poultry industry now had specific policy and guidelines for dealing with environmental issues, and the nonpoultry citizenry had assurance that the broiler operations would be held to a standard of operation. At this time, the level of communication and trust between all parties is greatly improved.

Dietary Amino Acid and Sodium Bicarbonate Responses in Broilers Reared in Hot Environmental Temperatures

Better environmentally controlled broiler houses have resulted in many integrated broiler operations using the same dietary feed formulations in winter and summer months due to only minor differences in environmental temperature in the broiler house. Much research has addressed broiler nutrient needs in thermoneutral vs. hot temperature conditions, but research evaluating nutrient needs of broilers during moderate temperature conditions (tunnel-ventilated houses during summer months) is lacking. This study evaluates the impact of increasing dietary Lys and other essential amino acids, and the addition of dietary sodium bicarbonate in high and moderate temperature conditions. Experiment 1 was conducted in batteries and evaluated broiler nutritional responses (d 20 to 40) in hot-cyclic temperature conditions (26 to 34°C). Experiment 2 was conducted in floor pens and evaluated broiler nutritional responses (d 37 to 49) in environmental temperature ranges that mimic a tunnel-ventilated broiler house during summer months (26 to 31°C). In both experiments, dietary treatments had minimal impact on live performance and breast meat yield. Lower mortality (P < 0.06), however, was observed in broilers fed the low CP diet in the hot temperature environment.

Sources and Movement of Salmonella through Integrated Poultry Operations: A Multistate Epidemiological Investigation

The prevalence of Salmonella from numerous sources in 32 integrated broiler operations of high- and low-performing broiler houses was characterized from four states across four seasons. Previous studies of Salmonella in broilers have been limited in scope, offering only a snapshot of pathogen prevalence as seen on a small number of individual farms. Twenty-six different sample types were collected from the hatchery to the end of processing, and Salmonella was found in all sample types. A total of 10,740 samples were analyzed for Salmonella, and 973 (9.1%) of these samples, including 49 of 798 (6.1%) carcass rinse samples, were Salmonella positive. Hatchery transport pads (389 of 765, 50.8%), flies (28 of 150, 18.7%), drag swabs (57 of 402, 14.2%), and boot swabs (20 of 167, 12%) were samples from which Salmonella was most frequently isolated. Thirty-six different serotypes were identified, and the most frequently encountered serotypes were Salmonella Senftenberg, Salmonella Thompson, and Salmonella Montevideo. Determining critical contaminating sources and following the movement of Salmonella through integrated poultry operations will help researchers and the industry develop practical intervention strategies.

Obstacles and Challenges in Implementing New Technologies in the Poultry Industry

The poultry industry is the most successful application of vertical integration in agriculture and has been successful because of the rapid adoption of new technologies and the successful implementation of the new products and processes into day-to-day operations. However, the adoption of new technology and its implementation into the broiler operations is not without the surmounting of numerous hurdles and obstacles.Although the obstacles are numerous, they can be divided into five groups that are internal to the company and two that are external. These groups are 1) management-level, organizational-decision making obstacles; 2) economy-cost return obstacles; 3) laboratory to field obstacles; 4)human inter-relationship obstacles; and 5) success-risk obstacles. The external groups of obstacles are 1) government and regulations and 2) consumer preferences.

Growth Kinetics of Salmonella Isolates in a Laboratory Medium as Affected by Isolate and Holding Temperature

Salmonella isolates were surveyed for their growth kinetics in a laboratory medium for the purpose of identifying isolates suitable for modeling experiments. In addition, the effect of holding stationary phase Salmonella cultures at different temperatures on their subsequent growth kinetics was evaluated for the purpose of developing a protocol to prevent the need for midnight sampling in modeling experiments. In Experiment 1, 16 isolates of Salmonella, 2 from the American Type Culture Collection (ATCC) and 14 from broiler operations, were surveyed for their growth kinetics in brain heart infusion (BHI) broth at 40°C. Lag time (P = 0.005) and growth rate (P = 0.022) were affected by identity of the isolate. Lag time ranged from 0.73 to 1.38 h, whereas growth rate ranged from 0.78 to 0.94 log10 CFU/ml/h. Overall, isolate S1 (Salmonella infantis from ATCC) was the fastest growing. In Experiment 2, 4 isolates of Salmonella, 1 from ATCC and 3 from broiler operations, were used to determine whether holding temperature influences subsequent growth kinetics. Salmonella isolates were grown to stationary phase at 37°C in BHI and then held for 24 h at 5, 22, or 37°C before dilution and reinitiation of growth in BHI at 37°C. Holding temperature did not alter or interact with identity of the isolate to alter subsequent growth kinetics. From the latter finding, a protocol was devised in which a dual-flask system is used to prevent the need for midnight sampling in modeling experiments. Similar to the results obtained in Experiment 1, identity of the isolate had only minor effects on growth kinetics in Experiment 2 indicating that all isolates examined were suitable for modeling experiments.

Heterogeneity of staphylococci and other bacteria isolated from six-week-old broiler chickens

In broiler operations, various health problems develop during the final 2 wk of the growing period, resulting in increased mortality and condemnation losses. At this stage, sickly birds were found to be systemically infected by various bacteria regardless of varied clinical signs, and the purpose of this study was to carry out thorough microbiological investigations on this problem. Thirty-one 6-wk-old broilers showing signs of illness were obtained from three farms, and bacterial isolations were carried out from the blood, liver, and hock joint. Bacteria were isolated from 87, 90, and 71% of the blood, liver, and hock joint samples, respectively. Mean bacterial counts in log10 of the blood (per milliliter) and liver (per gram) were 2.15 and 2.93, respectively. Among 132 bacterial isolates, major species were Staphylococcus (60%), Corynebacterium (18%), Escherichia coli (5%), and Stomatococcus (4%). Among 79 Staphylococcus isolates, 77 were coagulase-negative. Major species of staphylococci were S. lentus (19%), S. simulans (18%), S. cohnii (13%), S. gallinarum (10%), and S. captis (7%). In addition, six species of gram-positive and five species of gram-negative organisms were isolated. Thus, the apparent systemic infections were not caused by predominant pathogenic bacterial species, and adequately described as mixed infections. There were some significant relationships between isolated bacterial species and sampling sites, suggesting that certain organisms were abundant in the environment of a particular poultry house. These results indicate that systemic infections in market age broilers are caused by mixed bacterial species and suggest that they are caused by suppressed host antibacterial systems rather than pathogenic factors of microorganisms.

Identification and Characterization of Salmonella Isolates by Automated Ribotyping

A study was conducted with the RiboPrinter, an automated ribotyping system, to evaluate its ability to identify and characterize isolates of Salmonella from broiler operations. Isolates of Salmonella obtained from a local broiler company were serotyped by a reference laboratory and ribotyped using the RiboPrinter. The RiboPrinter generated ribotype patterns by probing EcoRI digests of Salmonella DNA with an E. coli DNA probe to the ribosomal RNA operon. The RiboPrinter identified isolates by band matching of their ribotype patterns to ribotype patterns in its database. In addition, the RiboPrinter characterized isolates by sorting them into ribotypes on the basis of the similarity of their ribotype patterns. Of 117 isolates, the RiboPrinter identified 34 (29%) at the serotype level, 11 (9%) at the strain level, 46 (39%) at the genus level, and 26 (22%) were not identified. Thus, only 38% of the isolates were identified at or below the serotype level, indicating that the RiboPrinter was limited in its ability to identify Salmonella isolates by band matching. In contrast, the RiboPrinter was very effective at characterizing Salmonella isolates. Out of 108 isolates, the RiboPrinter detected 31 ribotypes, compared to serotyping which only detected 22 types of Salmonella. Thus, automated ribotyping was more discriminatory than serotyping. However, when results of both typing methods were combined, 40 types of Salmonella were detected, indicating that the best discrimination was obtained when automated ribotyping and serotyping were used together.

Changing epidemiology of ascites in broiler chickens

Ascites has become a major economic problem in modern broiler operations world wide. Estimated losses to the global economy likely amount to hundreds of millions of dollars annually, however, accurate statistics are not available. Epidemiological information on incidence of ascites is scanty. The present work examines the condemnation records between 1986 and 1994 from federally inspected slaughtering plants in Canada. The analysis reveals that there has been a steady increase in ascites condemnation during this period. National average figures showed a nearly sixfold increase in condemnations due to ascites from 1986 to 1994. It is estimated that in Canada some 6–8 million chickens developed ascites in 1994. The present data have shown an alarming trend in the epidemiology of ascites. Key words: Chicken, broiler, ascites, condemnation, epidemiology

An Atypical Fowl Pox Outbreak in Broilers in Southern Brazil

An unusual fowl pox outbreak occurred in two integrated broiler operations. The uncommon characteristic of this outbreak was that the pox lesions were manifested in the feathered parts of the body, mainly in the posterior dorsal area and external part of the thigh. Diagnosis was made by means of histopathology and virus isolation. Severe losses were incurred at the processing plant as a consequence of condemnation due to dermatitis. Vaccination of day-old chicks with mild fowl pox vaccine combined with Marek's disease (HVT) vaccine in the area of the outbreak appeared to be important in controlling the disease.

Sensitivity of Avian Eimeria spp. to Seven Chemical and Five Ionophore Anticoccidials in Five Belgian Integrated Broiler Operations

Coccidia were isolated from 122 Belgian broiler farms without clinical coccidiosis. Shuttle programs including robenidin or nicarbazine in the starter (7-14 days) followed by an ionophore or diclazuril in the grower ration were most commonly used. Out of 215 coccidiosis-positive groups, 146 Eimeria acervulina, 65 E. maxima, and 88 E. tenella isolates were tested without further laboratory propagation in 17 sensitivity profiles. For each profile, oocytes were pooled from 9 +/- 4 farms (mean +/- SD) that used the same anticoccidial program and that belonged to the same integrated broiler operation. Each suspension contained an equal number of isolates and oocyst numbers from each farm tested. Each profile included an unmedicated uninfected group, an unmedicated infected group, and 11 medicated infected groups, consisting each of three replicates of three Ross chicks. Medication started at 8 days of age, and each inoculated bird received 50,000 sporulated oocysts at 10 days. Results were related to the anticoccidial program that had been in use. Chemical drugs showed the highest activity against Eimeria, whereas ionophores were less efficacious. Of the latter, monensin (110 ppm) was least active; narasin (70 ppm), salinomycin (60 ppm), and maduramicin (5 ppm) took an intermediate position, and lasalocid (90 ppm) was most active. A 50% improvement in weight gain was obtained in 7 to 10 out of 17 profiles with 100 + 8.35 ppm clopidol/methylbenzoquate (10), 125 ppm nicarbazin (9), 3 ppm halofuginone (8), and 1 ppm diclazuril (7). A 50% improvement in feed conversion was obtained in 7 to 11 profiles with nicarbazin (11), halofuginone (10), diclazuril (9), 33 ppm robenidine (9), clopidol/methylbenzoquate (7), and lasalocid (7). Based on relative oocyst output, the highest activity against E. acervulina was obtained with clopidol/methylbenzoquate (8/16); the highest activity against E. maxima was obtained with lasalocid (6/6), diclazuril (5/6), and halofuginone (5/6); and the highest activity against E. tenella was obtained with diclazuril (8/8), amprolium/ethopabate (5/8), halofuginone (4/8), maduramicin (4/8), and nicarbazin (4/8).