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This study was conducted to evaluate the effects of 3 rearing systems (FL: flooring litter rearing, MC: multilayer cage rearing, PN: plastic net rearing) with or without supplemental narasin on growth performance, gastrointestine development and health of broilers. A total of 2,400 one-day-old Ross 308 mixed-sex broilers (1:1 ratio of males and females) were used in a completely randomized design utilizing a 3 × 2 factorial arrangement of treatments, with 12 replicates per treatment. Each replicate for FL, MC, and PN consisted of 34 birds per floor pen, 30 birds per cage, and 36 birds per net pen, respectively, ensuring the same stocking density (12 birds/m 2 ) across the 3 systems. Results showed that lower ADG (average daily gain), ADFI (average daily feed intake), and FCR (feed conversation ratio) observed in the MC group than those of the other 2 systems from 1 to 36 d of age (P < 0.05). Narasin inclusion in the diets decreased ADFI and FCR significantly (P < 0.05). Multilayer cage and PN rearing systems reduced the relative weight of the gizzard significantly (P < 0.05). Compared with FL, MC reduced the relative weight of the duodenum, jejunum, and ileum (P < 0.05). The mRNA expression levels of the ileal IL-1β and IFN-γ in FL were higher than those in PN and MC (P < 0.05). Narasin decreased the ileal mRNA expression of TNF-α (P < 0.05). Different rearing systems changed the ileal microflora structure of broilers. The FL system increased the ileal microbial diversity of broilers and the relative abundance of Actinobacteria. Narasin combined with MC increased the relative abundance of Proteobacteria. In conclusion, birds reared in PN had a higher body weight. The MC birds had poorer intestinal development and health condition, higher abundance of Proteobacteria, but better FCR. The FL rearing appeared to be propitious for gastrointestinal development and health. Narasin inclusion in the diets improved FCR and changed the relative abundance Proteobacteria of broilers., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Two experiments were conducted to investigate the effects of tannic acid extract (TAE) formulations on the performance and intestinal health of male Cobb × Cobb 500 broilers exposed to coccidiosis. In the first experiment, 320 broiler chicks were randomly assigned to 5 treatments with 8 replicates. Treatments included non-medicated, uninfected (NC); non-medicated, infected (PC); salinomycin (SAL, 66 mg/kg); tannic acid (TA, 0.5 g/kg) and TAE (TAE, 0.5 g/kg). On d 14, all groups (except NC) were orally inoculated with Eimeria acervulina, E. maxima and E. tenella oocysts. Intestinal lesion scores, fecal oocyst counts (OPG) and performance were evaluated on d 20. The PC had greater lesions and higher FCR than infected, supplemented groups. Only TAE reduced OPG compared to PC (P < 0.05). In the second experiment, 3,000 broiler chicks were vaccinated on day of hatch with live coccidial oocysts, then randomly assigned to 5 treatments with 15 replicates. Treatments included non-medicated (CNT); salinomycin (SAL, 66 mg/kg); robenidine (ROB, 33 mg/kg); TAE (0.5 g/kg) and TAE with Bacillus coagulans (TAE+BC, 0.5 g/kg). On d 29, a subset of pens (n = 20) were challenged with a mixed Eimeria spp. oral inoculum; performance, lesions and OPG were evaluated on d 35. An immune challenge was created in half the pens by issuing broilers feed without supplementation materials during the challenge. For the non-challenged pens (n = 55), performance was measured up to d 49. Performance of non-challenged, vaccinated-CNT birds was improved with all treatments at d 21 and d 49. Among the challenged birds, withdrawal of SAL or ROB resulted in FCR similar to the challenged CNT group (P > 0.05), whereas withdrawal of TAE or TAE+BC maintained improved FCR compared to challenged-CNT birds (P < 0.05). These findings indicate supplementation of TAE and TAE+BC with coccidiosis vaccination can be considered as a potential alternative strategy to address coccidiosis in broiler chickens.

Biological supplements in poultry feed are of continued interest due to the improvements in growth performance, protection from pathogen invasion, and benefits in overall host health. The fermentation metabolites of Diamond V Original XPC™ (XPC) have previously been shown to improve commercial performance and reduce Salmonella in poultry. The current study sought to characterize the cecal microbiota using culture-independent analysis based on 16S rRNA gene in Coccivac-D sprayed broilers supplemented with XPC and/or Salinomycin (SAL). Ross 708 male broilers (n = 640) were assigned to one of 4 treatments: Cocci-vaccine (T1), Cocci-vaccine + XPC (T2), Cocci-vaccine + SAL (in the grower diet only) (T3), and Cocci-vaccine + SAL (in the grower diet only) + XPC (T4). Analysis with a PCR-based denaturing gradient gel electrophoresis (DGGE) indicated a shift in the microbial populations present at the various sampling ages - 16, 28, and 42 days. Phylogenetic analysis indicated further consistency in microbial communities directly related to bird age. Identification of microbial communities present and the assessment of their respective quantities using an Illumina MiSeq indicated treatment with XPC had no significant impact on microbial diversity (Chao1 index, observed operational taxonomic unit (OTU) and phylogenetic diversity (PD) whole tree). Sampling age revealed significantly greater diversity at 16 and 28 d (P < 0.05) as compared to the 42 d for the Shannon diversity index, while showing significantly decreased richness and diversity in the 42 d sampling age (Chao1 and observed OTU; P < 0.05). The results of the current study indicate that the chicken intestinal microbiota are impacted more by temporal changes rather than by the feed additive studied., (© 2017 Poultry Science Association Inc.)

Supplementation of poultry diets with Diamond V Original XPC™ (XPC) has been proposed as a means to ameliorate the commonly observed loss of appetite and depression of growth in birds given a live coccidiosis vaccine. A study was conducted to compare the effects on bird performance of a live coccidiosis vaccine in broilers, with and without the dietary inclusion of XPC (1.25 g/kg). Ross 708 male broilers (n = 1,280) were allocated to one of 4 feed treatments: cocci-vaccine (T1), cocci-vaccine + XPC (T2), cocci-vaccine + salinomycin in the grower diet only, (T3), and cocci-vaccine + salinomycin in the grower diet + XPC (T4). Birds consuming diets containing XPC (T2 and T4) and salinomycin (T3) exhibited increased (P < 0.05) feed intake and significantly heavier body weights at 28 d (1.70, 1.74, and 1.67 kg, respectively) and 42 d (3.29, 3.31, and 3.26 kg, respectively). Feed conversion ratio at 28 d was improved (P < 0.05) by adding XPC to diets (T2: 1.47 and T4: 1.44) compared to control diets (T1: 1.50 and T3: 1.47). Salmonella prevalence determined via selective media indicated the inclusion of XPC in the diet resulted in a significant reduction of Salmonella when compared to treatments lacking XPC. Molecular confirmation of Salmonella species indicated S. Kentucky to be present in 38 of the 39 positive samples. Results revealed the ability of XPC in reducing the prevalence of Salmonella. Results from this study also suggest that XPC could be used in conjunction with a live coccidiosis-vaccine to increase growth rate and improve feed conversion of broilers. However, further work is needed to delineate more specific effects directly attributable to XPC., (© 2017 Poultry Science Association Inc.)

Effects of commercial antimicrobials and the individual and combinational use of commercial prebiotics and probiotics in feed from d zero to 41 on the growth performance, small intestine size, jejunal morphology, and ileal resident bacteria population of broiler chickens were determined. A total of 1,040 one-day-old male Ross × Ross 708 broilers were randomly distributed to 80 floor pens (5 treatments, 16 replications per treatment, 13 chicks per pen). Five dietary treatments were employed: 1) a corn soybean-meal basal diet (served as a negative control diet, NC); 2) a basal diet supplemented with a commercial prebiotic product (Pre); 3) a basal diet supplemented with a probiotic product containing Bacillus subtilis spores (Pro); 4) a basal diet supplemented with both prebiotic and probiotic products (Pre + Pro); and 5) a basal diet supplemented with commercial antimicrobials (served as a positive control diet, PC). At d 14, Pre diets improved the relative level of Lactobacillus in ileal mucosa as compared to NC, Pro, or PC diets (P = 0.045) without improving broiler BW. Broilers fed PC diets exhibited the highest BW gain from d 15 to 27, the lowest duodenum, jejunum, and ileum relative weights as percentage of BW at d 27, and the highest breast weight at d 42 (P = 0.026, 0.035, 0.002, 0.025, and 0.035, respectively). Broilers fed Pro or Pre + Pro diets exhibited higher BW gain from d 28 to 41 (P = 0.005) and higher overall BW gain from d zero to 41 (P = 0.039) than those fed other diets. Dietary treatments did not affect jejunal morphology or ileal resident Escherichia coli level at any age. From our results, including spores of Bacillus subtilis in feed may stimulate growth at a later age and may facilitate broilers in reaching their target weight sooner. Therefore, probiotics are recommended as potential alternatives to antimicrobials in chicken diets, especially in grower and finisher feed., (© 2016 Poultry Science Association Inc.)

Five successive flocks of broilers were reared in floor-pens and given different drug programs or were vaccinated against coccidiosis. Oocysts of Eimeria were isolated from the litter of pens during the fifth flock and their sensitivity to salinomycin (Sal) investigated by measuring new oocyst production following infection of medicated and unmedicated birds. Parasites obtained following 5 flocks given Sal were not well-controlled and it was concluded that they were partially resistant to the drug. Parasites obtained following 4 unmedicated flocks and one medicated flock were better controlled by Sal and it was concluded that in the absence of continuous medication there had been an improvement in drug efficacy. Sal almost completely suppressed oocyst production of isolates from treatments in which medication was followed by vaccination, indicating that when a drug program is followed by vaccination, restoration of sensitivity to Sal had occurred., (© 2015 Poultry Science Association Inc.)

The annual financial loss to the poultry industry as a result of coccidiosis has been estimated at about US $3 billion. The objective of this study was to evaluate and compare the effects of probiotics and salinomycin as feed additives on performance and coccidiosis control in male broilers raised to 42 d of age. The study consisted of 360 Cobb male broiler chickens randomly allocated to 4 groups each with 3 replicates. Group 1: untreated, unchallenged negative control group (NC); group 2: untreated, challenged positive control group (PC); group 3: negative control supplemented with salinomycin 66 mg/kg, challenged group (Sal); and group 4: negative control supplemented with probiotics, challenged (Prob mix). On d 15, all birds (except group 1) were challenged with approximately 75,000, 25,000, and 75,000 of Eimeria acervulina, Eimeria maxima, and Eimeria tenella oocytes, respectively, that were mixed into the feed. Feed conversion ratio and mortality were recorded throughout the experiment. On d 21 and 42, intestinal lesions and litter conditions were scored. On d 7, 14, 21, 28, 35, and 42, oocyst counts were determined from 10 freshly collected fecal samples per pen. The results showed that mortality, litter, and lesion scores at d 21 and 42, and oocyst shedding at d 21 did not differ significantly between the Prob mix and the Sal groups. However on d 28, oocyst shedding was significantly lower in the Sal group than in the PC group but insignificantly lower than the Prob mix group. Body weights of the Prob mix group at d 42 were significantly lower than the Sal group; however, the feed conversion ratio values were similar between the 2 groups. The results of this study showed that probiotics supplementation could be considered as a potential strategy to control coccidiosis in broiler chickens., (©2014 Poultry Science Association Inc.)

The efficacies of 5 widely used dietary supplements were investigated on performance indices, fecal oocyst excretion, lesion score, and intestinal tract measurements in healthy and Eimeria spp.-infected birds by using a comparative model. This study included 2,400 sexed Ross 308 broiler chicks that were equally divided in 2 groups: the infected group, experimentally infected with oocysts of mixed Eimeria spp. at 14 d of age, and the healthy controls. The birds in both groups were further divided equally into 6 groups, of which one was fed a basal diet and served as control without treatment and the other 5 served as experimental treatments. These 5 groups were fed 5 diets containing preparations of 60 mg/kg of anticoccidial salinomycin (SAL), 1 g/kg of multienzyme (ENZ), 1 g/kg of probiotic (PRO), 1 g/kg of prebiotic (PRE), and 40 mg/kg of an herbal essential oil mixture (EOM). Body weight gain and feed conversion ratio (FCR) showed significant improvement in the infected animals, which indicates that dietary supplemental regimens with SAL, ENZ, PRO, and PRE initiated in 1-d-old chicks reduced adverse effects after challenge with coccidiosis; however, chicks that were administered EOM failed to show such improvement. Uninfected chickens showed significant improvement in FCR with supplements SAL, PRE, and EOM, which signifies significant (P < 0.01) infection by supplement interactions for BW gain and FCR. In the infected group, all of the supplements reduced the severity of coccidiosis lesions (P < 0.01) induced by mixed Eimeria spp. through the middle and lower regions of the small intestines, whereas supplementation with SAL or EOM alone was effective (P < 0.01) in reducing oocyst excretion compared with the control treatment. The data indicated that use of these subtherapeutically efficacious supplements (except EOM) in broiler production can lessen the depression in growth due to coccidial challenge.

The effects of salinomycin (SAL) on protective cell-mediated immune (CMI) responses of vaccinated and challenged broiler chicks against hydropericardium syndrome virus (HPSV) and Newcastle disease (NDV) were investigated while comparing 3 reference drugs [levamisole, cyclophosphamide (CYP), and cyclosporine (CYS)]. Peripheral lymphoproliferation, skin hypersensitivity reactions, and the ability of chicks to resist virulent HPSV and virulent NDV challenges were used to determine the effects of drugs on CMI responses in chicks. Salinomycin-medicated chicks showed significant (P < 0.05) stimulation of lymphoproliferation and nonsignificant (P > 0.05) stimulation of skin hypersensitivity reactions compared with untreated control chicks. However, skin thickness and lymphoproliferation of SAL-medicated chicks were significantly greater (P < 0.05) than those of CYP- and CYS-treated chicks. The greatest survival rate was recorded in SAL-medicated chicks compared with immune-suppressed (CYP- and CYS-treated) and untreated control chicks after virulent NDV and virulent HPSV challenges. Thus, it was concluded that SAL had beneficial effects on the CMI responses of broiler chicks against HPSV and NDV.

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.

The pleuromutilin antibiotic tiamulin (TIA) is known to produce a negative interaction in broilers when administered in combination with several ionophore anticoccidials such as salinomycin (SAL). Chlortetracycline (CTC), when administered simultaneously with TIA, has demonstrated a synergistic antimicrobial effect. A 35-d feeding study was conducted in cages to evaluate the interaction effect of a combination of TIA plus CTC at increasing inclusion levels when administered concurrently with SAL. A total of 200 one-day-old broiler chicks were distributed into 4 groups, and each group consisted of 5 cages containing 10 birds in each. Replicate cages were distributed randomly. Feed for all groups contained 60 ppm SAL, but additionally, 0, 20, 30, and 50 ppm TIA and 0, 60, 90, and 150 ppm CTC were included, respectively. Several enzymes (creatine phosphokinase, lactate dehydrogenase, and aspartate aminotransferase) were determined from blood samples taken at the end of the trial. Blood samples were also collected during d 0, 19, and 35 and were analyzed for antibody titers against Mycoplasma gallisepticum and Mycoplasma synoviae. Necropsy of a few birds (20, 8, 20, 12, and 12 on d 7, 14, 21, 28, and 35, respectively) was conducted at weekly intervals. Results indicated that there was a significant depression of weight gain (P < 0.05) in group 4 (TIA 50 + CTC 150) only. The final weights were 1,809 +/- 130, 1,859 +/- 52, 1,703 +/- 47, and 1,617 +/- 98 g for groups 1 (TIA 0 + CTC 0), 2 (TIA 20 + CTC 60), 3 (TIA 30 + CTC 90), and 4 (TIA 50 + CTC 150), respectively. However, feed intake and feed conversion efficiency (g of weight gain/kg of feed intake) were not significantly affected in any of the groups. There was no dose-related adverse effect on mortality or clinical signs exhibited during the trial, and this was supported by necropsy. Maternally derived antibodies against M. gallisepticum were present at the beginning of the trial but disappeared within 19 d. Otherwise, there was no apparent infection by M. gallisepticum or M. synoviae throughout the trial. The results demonstrate that 50 ppm TIA plus 150 ppm CTC along with 60 ppm SAL caused only a depression of growth, but no adverse signs of interaction were detected. Taking into consideration all the aspects of the cost of production, the 20 ppm TIA plus 60 ppm CTC was the most cost-effective level to administer continuously with 60 ppm SAL via the feed, but it would be important to do an additional study using an artificial infection with M. gallisepticum or M. synoviae to know whether this inclusion rate would be sufficient to protect against an infectious challenge.

Direct-fed microbials (DFM) could serve as a potential alternative to the feeding of antibiotics in poultry production. In this study, the effects of providing a DFM were compared with the feeding of salinomycin on intestinal histomorphometrics, and microarchitecture was examined. Broiler chicks (n=18 per treatment; trials 1 and 2) were fed a standard starter diet (control), control+PrimaLac (DFM; 0.3% wt/wt), and control+salinomycin (SAL; 50 ppm) from hatch to 21d. The birds were euthanized on d 21, and the ileal, jejunal, cecal, and colon tissues were dissected. Samples were examined by light microscopy (jejunum and ileum; trial 1) and scanning electron microscopy (ileum, cecum, and colon; trial 2). Feeding of the DFM increased intestinal muscle thickness (P<0.05) up to 33% compared with the control treatment. The DFM group also had increased villus height and perimeter (P=0.009 and 0.003, respectively) in jejunum. Segmented filamentous-like bacteria were less numerous in DFM-treated chicks than in the control chicks. Very few segmented filamentous-like bacteria were found near other microbes in the ileum. The DFM chicks had a larger number of bacteria positioned over or near goblet cells and in intervilli spaces. Bacteria in the colon were observed to be attached primarily around and within the crypts. Mucous thickness was less, and the density of bacteria embedded in the mucous blanket appeared to be lower in DFM-treated animals than in the control in all intestinal segments. The birds fed SAL had fewer bacteria and enterocytes in the ileum than in the control-and DFM-treated birds, and they had thicker and fewer microvilli. Because gastrointestinal track colonization by the DFM organisms can prevent the attachment of pathogens to the epithelium, spatial relationships, in this study, demonstrate the functionality of DFM and probiotics in preventing disease. It also supports previous observations that the feeding of salinomycin may alter intestinal function.

The current study investigated whole-body O2 consumption, intestinal O2 consumption, and intestinal inflammation status through mucosal cytokine production on broiler chicks fed the direct-fed microbial PrimaLac. One hundred twenty 1-d-old broiler chicks were randomly assigned to 1 of 3 experimental diets: standard starter diet (control), standard starter diet with added salinomycin (SAL), and standard starter diet with added PrimaLac (DFM). Birds were housed in 2 separate rooms, the control and SAL treatments in one room and the DFM in another. Intact ileal and cecal samples were collected on d 19, 20, and 21 after measuring whole-body O2 consumption using indirect calorimetry. The O2 up-take of ileal tissue was measured using an in vitro O2 monitor. Analysis of intestinal immune status of broilers was measured by the relative differences in mRNA of both pro- and antiinflammatory cytokines: interleukin-(IL) 1beta, IL-6, and IL-10 using real-time reverse transcription-PCR. Broilers exhibited a 6 to 16% decrease in whole-body energy expenditures and up to a 47% decrease (P<0.05) in ileal energy expenditures in the DFM group compared with other treatments. The reverse transcription-PCR data demonstrated that DFM consortium numerically altered both pro- and antiinflammatory cytokines within the ileum of 19-d posthatch broilers. These data suggest that direct-fed microbials like PrimaLac increase metabolic efficiency via changes in intestinal physiology and metabolism.

A feeding experiment was carried out over 42 d with four groups of broiler chickens fed experimental diets formulated to provide no supplementation, 20 mg zinc bacitracin, 60 mg salinomycin, or both feed additives in combination. During the fifth week of the experiment, four chickens from each pen were killed, and the contents of gizzard, duodenum, jejunum, ileum, ceca, and rectum were separately collected and pooled. In all intestinal segments, the pH and the concentration of lactic acid were measured, and the numbers of anaerobic bacteria, coliforms, lactic acid bacteria, lactobacilli, enterococci, and Clostridium perfringens were counted. In homogenates of pancreas obtained from four animals, the activities of amylase, lipase, trypsin, and chymotrypsin were measured. A significant growth-promoting effect was observed in the group receiving zinc bacitracin in combination with salinomycin. Zinc bacitracin significantly reduced the number of coliform bacteria in the ileum and increased the activities of amylase and lipase in pancreas homogenates. Supplementation with salinomycin and zinc bacitracin, alone or in combination, resulted in significantly lower counts of C. perfringens as well as Lactobacillus salivarius, which was a dominant lactic acid bacterium found in broiler intestinal contents. High numbers of these lactobacilli may play a role in broiler growth depression related to competition in nutrient uptake or impaired fat absorption due to bile acid deconjugation.

Intestinal colonization and shedding of pathogenic bacteria in animal feces is an important factor in both human food safety and animal health. The effect of broiler feed additives flavophospholipol (FPL; Flavomycin, bambermycins) and salinomycin sodium (SAL; Sacox) given singly on the excretion of Salmonella enteritidis, Campylobacter jejuni, and Clostridium perfringens was studied following controlled infection. The incidence of shedding (number of birds with positive fecal cultures) and the degree of shedding (cfu per gram of feces in positive birds) were measured to determine the influence of these two common feed additive antibiotics on shedding rates of potential pathogens. A total of 216 Ross broiler chickens, housed in battery cages, were fed either an unmedicated feed (controls), feed containing FPL, or feed containing SAL. Feed treatment groups were subdivided into three bacterial challenge groups of 24 chicks, each receiving only one of the pathogens. Bacterial challenge was administered orally on Days 11 and 12 for Salmonella and Campylobacter and on Days 2 and 3 for Clostridium. Fecal samples were collected weekly up to 6 wk of age and cultured for presence of the target organism. The shedding rate was determined by decimal dilutions of the fecal samples. Feeding FPL resulted in a reduced (P < or = 0.05) degree and incidence of Salmonella and Clostridium shedding at 6 wk. Feeding SAL reduced (P < or = 0.05) the incidence of Salmonella shedding at 6 wk. Neither feed additive affected the incidence nor the degree of Campylobacter shedding. The results of this study indicate that these feed additives may reduce the incidence of these potential human and animal pathogens in preslaughter broilers.

Three experiments (Exp.) were conducted to determine the interactive effects of sodium bentonite (NaB) with the efficacy of monensin (MON) or salinomycin (SAL) in coccidiosis-infected chicks. Male broiler chicks 5 to 14 d of age were used, and each treatment was replicated with eight (Exp. 1) or four (Exp. 2 and 3) pens of five chicks each. In Exp. 1, MON (80 ppm), NaB (0.50%), or MON+NaB were fed to uninfected and coccidiosis-infected (5 x 10(5) sporulated Eimeria acervulina oocysts on Day 2 of the Exp.) chicks in a 2 x 2 x 2 factorial arrangement of treatments. Experiment 2 was identical to Exp. 1, but SAL (30 ppm) replaced MON as the anticoccidial additive. In Exp. 3, MON (55 ppm) or SAL (22 ppm) were added individually or with NaB (0.50%) to diets for uninfected or coccidiosis-infected chicks. Coccidial infection reduced (P < 0.01) gain, feed intake, gain:feed, plasma carotenoids, and percentage tibia ash in all experiments. The MON and SAL additions increased these response criteria in infected chicks (coccidiosis by anticoccidial, P < 0.07), except MON did not increase (P > 0.10) feed intake or tibia ash in Exp. 3. In Exp. 3, NaB partially reduced the positive effect of MON on daily gain (NaB by MON, P < 0.03), and of SAL on feed intake (NaB by SAL, P < 0.08). The NaB addition also increased gain:feed (P < 0.08), and the increase was greater in infected chicks (coccidiosis by NaB, P < 0.08). Also in Exp. 3, SAL increased feed intake more in chicks not fed NaB than in chicks fed NaB (SAL by NaB, P < 0.08). Dietary NaB (0.5%) may reduce the efficacy of MON and SAL in coccidiosis-infected chicks when these additives are added at less than recommended levels.

At 7 d postinoculation (DPI) with a mixed culture of avian Eimeria species, 21-d-old chicks maintained in batteries and floor pens on a diet containing 0.15% (3 lb/ton) betaine plus 66 ppm (60 g/ton) salinomycin were significantly heavier and had significantly lower feed conversion ratios and mortality than chicks fed diets containing 0.15% betaine or 66 ppm salinomycin alone, or the control diet. At 31 DPI, when the chicks were 45 d old, the differences between the diet groups were not as great as at 7 DPI. In vitro, except at high concentrations, betaine was nontoxic to sporozoites of Eimeria tenella or Eimeria acervulina and had little effect on their invasion and development in cultured cells. In vivo, invasion by E. tenella and E. acervulina sporozoites was significantly reduced in all chicks fed diets containing betaine or salinomycin compared with that in control chicks. There was a significant interaction between betaine and salinomycin that impacted on invasion by both species. Overall development of E. tenella did not appear to be adversely affected by addition of betaine to diets containing salinomycin. Conversely, development of E. acervulina was reduced in chicks fed diets containing 0.075% (1.5 lb/ton) betaine plus 66 ppm salinomycin as compared with that in chicks fed salinomycin alone.

Live performance and carcass quality of female broilers were evaluated under four coccidiostat programs (CP) and two feed treatments. The CP consisted of halofuginone (H) and salinomycin (S), fed either continuously (HH and SS) or in rotational programs (HS and SH), during the starter (1 to 21 d) and grower (22 to 35 d) periods, respectively. All groups received an unmedicated withdrawal feed from 36 to 42 d. Feed treatments consisted of a control and a fortified diet high in proline and supplemented with additional ascorbic acid and zinc (50 birds per pen; 4 pens per feed; 8 pens per CP). In addition to live performance and skin puncture strength, carcass quality attributes following processing (at 43 d of age) were assessed. No CP by feed interactions were detected for any of the variables measured. The CP treatments did not differ for live performance. Birds on fortified feed were heavier at 21 d (P < .001) and had an improved feed conversion at 42 d (P < .05). Skin puncture strength was significantly reduced for the birds fed H, either in continuous (HH) or rotational programs (HS and SH). Skin sores-scratches and tears were lowest for the SS and SH groups. The HH treatment resulted in fewer grade A carcasses (P < .001). Halofuginone, when fed continuously or in the starter feed, affected carcass quality of broilers. Higher dietary proline or supplementation with ascorbic acid and zinc did not appear to alleviate the effects of halofuginone on skin quality.

Live performance and skin characteristics of male and female broilers were evaluated under four coccidiostat feed additive programs. Treatments consisted of halofuginone (H) and salinomycin (S), fed either continuously (HH and SS) or in rotational programs (HS and SH) during the starter (1 to 21 d) and grower (22 to 35 d) periods, respectively. An unmedicated withdrawal feed was provided from 36 to 42 d of age. Body weights, feed efficiency, and mortality (by pen) were determined, in addition to skin puncture strength measurements taken at Days 21, 35, and 42 on five birds per pen. At 43 d of age, all birds were processed and individually graded for skin defects. There were no treatment by sex interactions for any variable measured. Male body weights, feed efficiency, and total mortality exceeded those of females (P < .05). Skin puncture strength was reduced at 21 d in the HH and HS groups, at 35 d in the HH and SH groups, and at 42 d in the HH, HS, and SH groups. Thigh sores and scratches were higher for the HH group (P < .05), and thigh skin tears were higher for the HH and HS groups (P < .01). Males had more swollen hock joints and breast blisters than females (P < .001). Females had more thigh skin tears (P < .01) and broken wings (P < .001) than males. Results of the present study demonstrated that halofuginone affected skin strength of broilers, especially when used continuously or only in the starter feed (1 to 21 d).

The anticoccidial activity of the ionophore CP-82,009 against laboratory isolates of four major species of poultry Eimeria was investigated. Parameters of anticoccidial efficacy that were evaluated were control of lesions and weight suppression. At 4 and 5 ppm, CP-82,009 demonstrated broad-spectrum anticoccidial efficacy in battery trials that was equivalent to reference commercial ionophores. When CP-82,009 was fed to uninfected broiler chickens at efficacious dose levels, growth rate and feed efficiency were found to be equivalent to commercial agents over a 21-day period in batteries and over a 49-day period in floor pens. From the present studies, it appears that CP-82,009 is an efficacious anticoccidial that is well tolerated by chickens, and that it ranks among the most potent anticoccidial ionophores described to date.

One study was conducted utilizing 192 male broilers, at 4 to 7 wk posthatching, to evaluate a narasin-nicarbazin drug combination (Maxiban) for effects on bird growth rate, feed efficiency, and survivability during cycling ambient temperature (24 to 35 C) distress. Maxiban did not impact (P greater than .1) live weight gain, but reduced (P less than .05) gain:feed ratio (unadjusted for mortality), from .29 for controls to .21 as bird survivability declined (P less than .05) from 87.5 to 69.8%. Adjusting feed efficiency by adding the gain of birds dying of heat prostration to that for birds surviving the experiment resulted in feed efficiency for Maxiban-supplemented birds being similar (P = .48) to birds not consuming Maxiban. Under the conditions of the present study, Maxiban increased the mortality rate of male broilers exposed to cycling ambient temperature of 24 to 35 C during 4 to 7 wk posthatching.

Broilers were grown to 42 days of age on diets supplemented with salinomycin (60 mg/kg), monensin (99 mg/kg), or halofuginone (3 mg/kg) and continued on unmedicated diets to 49 days of age. There were no significant (P greater than .05) differences among anticoccidials in final body weight, feed conversion, or mortality rates. Samples of birds were processed for dressing percentage and parts yield. Both males and females fed salinomycin had significantly higher breast meat yield as a percentage of postchill weight than those fed halofuginone but not those fed monensin; differences were not significant for breast meat yield of males or females fed monensin or halofuginone. Males fed halofuginone had significantly heavier leg quarters than those fed salinomycin but not those fed monensin. Females fed salinomycin had significantly higher water uptake during chill than those fed monensin or halofuginone. Results of the present study indicate that the anticoccidial used in growing broilers may influence some carcass yield parameters.

Six trials were conducted at various locations to determine the response of broiler chickens to combinations of zinc bacitracin and roxarsone when fed in the presence of narasin. The addition of zinc bacitracin at 55 mg per kg significantly improved growth rate and feed utilization when data from all locations were combined. There was no effect of roxarsone fed at 50 mg per kg on BW or feed utilization, nor was there an interaction of roxarsone and zinc bacitracin on BW. There was a significant interaction of roxarsone and zinc bacitracin for feed utilization; addition of zinc bacitracin significantly improved feed utilization both in the presence and absence of roxarsone, but the improvement was greater in the absence of roxarsone.

A factorial design (2 by 3) was used to evaluate the interaction between aflatoxin (0, 2.5, and 5 mg per kg) and salinomycin [0, 60 g per ton (909 kg)]. There were four replicates of 10 chicks per treatment. The chicks were maintained in batteries from 0 to 3 wk of age, with feed and water available for ad libitum intake. Aflatoxin at both levels (2.5 and 5 mg per kg) with and without salinomycin decreased body weight. The efficiency of feed utilization was affected only at the 5 mg per kg level of aflatoxin. Feeding 5 mg per kg of aflatoxin alone decreased the hemoglobin level. The inclusion of salinomycin (60 g per ton) in the diet with 2.5 or 5 mg per kg of aflatoxin initiated no significant change in body weight or feed efficiency. No significant interaction was observed between aflatoxin and salinomycin on any of the parameters measured.

The rate of feather growth was measured in Hubbard X Hubbard broilers given monensin, salinomycin, or lasalocid for 8 weeks in floor pens. Chicks were given a nutritionally adequate diet. Feathers on male chicks were shorter at 10 days of age but grew faster than those on female chicks. Male chicks had longer feathers than female chicks after 31 days of age. Back feather scores were similar in male and female chicks at 52 days of age. Dietary ionophores had no effect on the rate of feather growth or the back feather coverage under the condition of this study.

Two, 7-week floor pen experiments were conducted consecutively with male broilers and then female broilers to determine the effects of feeding salinomycin (60 ppm), monensin (99 ppm), or lasalocid (125 ppm) at the following three levels of dietary protein: 1) that which meets National Research Council specifications (NRC, 1977), 2) that level deficient in sulfur amino acids (SAA), or 3) that deficient in protein. Group body weights, feed intake, and water consumption were noted at 28 and 49 days of age with feed efficiency and overall mortalities determined. Reducing SAA resulted in depressed (P less than .05) body weights at 7 weeks in both experiments, whereas deficient protein reduced (P less than .05) growth, feed efficiency, and water consumption. Generally, inclusion of coccidiostats in the diet did not significantly hinder growth or feed efficiency. Feeding of coccidiostats in combination with the low protein diet did not produce additional anorexigenic effects. Although a significant lasalocid SAA-sparing effect was not observed, diet X coccidiostat interactions (P less than .05) were apparent and attributable to an apparent "protein-sparing" effect upon body weight gain when salinomycin was fed in combination with the low protein diet. Lasalocid increased water consumption (P less than .05) relative to monensin in the female broilers.

Five trials were conducted at various locations to determine the response of broiler chickens to the addition of zinc bacitracin to diets containing both salinomycin and roxarsone. Results indicate that when a combination of salinomycin and roxarsone is used as an anticoccidial, the addition of zinc bacitracin at 33 or 55 mg/kg diet will improve growth rate and feed utilization by broiler chickens. Regression of body weight and feed utilization on dietary levels of zinc bacitracin indicated that each milligram of zinc bacitracin in the diet increased the 49-day weight of broiler chickens by .92 g and reduced the feed required per gram of gain by .0012 g.

The effects of supplemental narasin (80 mg/kg) on several dietary factors were investigated in chicks infected with Eimeria acervulina. In Trial 1, chicks were fed a lysine-deficient corn-corn gluten meal diet containing graded increments of crystalline L-lysine.HCl with or without narasin. Supplemental narasin increased weight gain and feed efficiency at all lysine levels fed. Based upon slope-ratio methodology, efficiency of L-lysine utilization was virtually the same in both narasin-fed and control chicks. Trials 2 and 3 evaluated the effect of narasin on methionine utilization in crossbred chicks fed a methionine-deficient soy-feather meal diet supplemented with graded levels of DL-methionine. Narasin supplementation increased weight gain, feed efficiency, and utilization of supplemental methionine in chicks infected with E. acervulina (Trial 2), but had no effect on any of the performance parameters in uninfected chicks (Trial 3). The effects of dietary protein level and source and dietary electrolyte balance on the narasin response of commercial broiler chicks infected with E. acervulina were studied in Trials 4 and 5, respectively. In Trial 4, narasin supplementation increased performance in all cases, and protein source or level had no effect on the narasin response. In Trial 5, rate and efficiency of gain were improved as the electrolyte balance (meq Na + K-Cl/kg diet) increased from 100 to 250, with no further improvement being observed from 250 to 350 meq. Supplemental narasin improved performance and no interaction between electrolyte balance and narasin was observed.

Three polyether, ionophorous anticoccidial drugs were fed to broiler chickens in floor pens for 5 or 6 weeks, then withdrawn for 2 weeks or 1 week, respectively. With monensin and salinomycin there was evidence of increased feed consumption and compensatory growth during the first week, but not the second week, after drug withdrawal. There was no evidence of compensatory growth in birds fed lasalocid. Final weights were best in birds fed lasalocid and salinomycin in comparison with unmedicated controls and birds fed monensin. There was evidence of increased feed consumption and compensatory growth in some treatments in which birds weighed more than controls prior to drug withdrawal.

Five 7-day trials using 336, 24, 24, 40, and 40 Large White male turkeys when 7, 11, 15, 27, and 32 weeks of age, respectively, were conducted to determine the toxic effects of salinomycin. Salinomycin became more toxic as the age of the turkeys increased. When 7-week-old turkeys were fed diets containing 44 or 66 ppm salinomycin, only 1 of 84 died; when turkeys 27 or 32 weeks of age were fed those amounts, 13 of 20 died. Salinomycin at 22 ppm tended to depress rate of growth at young ages and to prevent or decrease growth and to increase mortality at older ages. Caution should be exercised to avoid salinomycin contamination of turkey diets.

Because monensin and salinomycin are widely used to control coccidiosis, two experiments were conducted to compare the performance of broiler chicks when these compounds were added to the diet. Five levels of each coccidiostat were fed. Increasing the levels of coccidiostat resulted in a decrease in body weight and feed intake. Monensin gave a greater depression at the level suggested by the manufacturer for prevention of coccidiosis (121 ppm) than did salinomycin (66 ppm). The interaction of experiment x treatment was significant and was a result of the greater performance depression at the lower levels (manufacturers' recommended levels) of coccidiostat administered in the first experiment than in the second. This research points out the necessity of the accurate use of the coccidiostats.

Six trials were conducted at different locations to examine the response of broiler chickens to roxarsone and bacitracin in the form of bacitracin methylene disalicylate (BMD) in the presence of the anticoccidal narasin. All diets contained narasin (80 mg/kg) and were fortified with a factorial arrangement of roxarsone (0 to 50 mg/kg) and BMD (0 or 55 mg/kg). Broilers were grown to market weights with narasin and roxarsone removed from the diets for the final 5 days. Addition of both roxarsone and BMD resulted in significant (P less than .05) improvements in body weight and feed utilization. Response to roxarsone for feed utilization was influenced to some extent by the presence or absence of BMD. Although the response to roxarsone was always positive, the degree of response was lessened by the presence of BMD. This resulted in a significant (P less than .10) interaction between roxarsone and BMD for feed utilization but not for body weight.

An experiment was conducted to evaluate antimicrobial resistance of coliforms and streptococci isolated from feces of chickens fed salinomycin. Two groups of 20 chickens were fed either a control feed or feed supplemented with 80 g/ton salinomycin. Chicken fecal coliforms and streptococci were isolated at 5, 15, 19, 22, 26, 33, 40, and 47 days of age and their resistance to 11 or 12 antibacterial agents (coliforms and streptococci, respectively) were determined in both groups of chickens. Salinomycin significantly reduced the number of coliforms resistant to sulfadiazine and reduced the number of streptococci resistant to erythromycin and lincomycin. Streptococci from birds fed salinomycin had lower minimum inhibitory concentrations for streptomycin. No streptococci isolates developed resistance to salinomycin. Coliforms from birds fed salinomycin had more (P less than .05) resistance patterns involving two, five, and six drugs. Numbers of coliforms resistant to streptomycin, ampicillin, carbenicillin, and cephalothin were greater (P less than .05) from birds fed salinomycin.

An experiment was conducted with young battery-reared chickens to evaluate the effects of graded levels of nicarbazin (0, 40, 80, 120, and 160 ppm) on plasma pigmentation in the presence and absence of coccidial infection. A second experiment was also performed to determine whether nicarbazin (50 ppm) and the narasin nicarbazin combination anticoccidial (50 ppm each) affected pigmentation values in coccidia-infected and healthy chicks. Pigmentation values were expressed as micrograms beta-carotenoid equivalents per milliliter of plasma (beta-CE). Results of these studies indicated that nicarbazin improved beta-CE in both parasitized and coccidia-free chicks, but the magnitude of improvement was greater in coccidia-infected animals. Linear responses to nicarbazin additions were observed in both groups. The second experiment revealed that the effects produced in healthy chicks receiving the narasin nicarbazin combination were equivalent to those which received nicarbazin alone, indicating that the nicarbazin response in beta-CE is manifested with the combination anticoccidial as well.

A 3 x 2 factorial floor pen experiment was conducted to determine the effects of feeding salinomycin (60 ppm) or maduramicin (5 ppm) for 49 days followed by a 3-day withdrawal ration upon both male and female broiler chickens in a coccidia-free environment. Body weights, feed intake, and water consumption were recorded at 28, 49, and 52 days of age. Feed efficiency and overall mortalities were also measured. Inclusion of either ionophore into the ration had no effect on final body weight, but improved feed conversion (P less than .05). Birds fed maduramicin drank more than the nonmedicated birds (P less than .05), which in turn, drank more than the birds fed salinomycin (P less than .05).

Two experiments were conducted to determine the influence of graded levels of salinomycin on the performance of broiler chicks. Cobb feather-sexed chicks were fed experimental diets from 1 to 21 days of age. A significant depression in body weight and feed consumption was obtained when the feed contained 77 ppm of salinomycin. Body weight and feed consumption was decreased approximately 10 and 13%, respectively, when the diet contained 88 ppm of salinomycin.

Feed taken from a commercial turkey farm where poults had refused to eat the feed and high mortality had occurred was analyzed and found to contain .81 mg/kg vomitoxin and 2.2 mg/kg salinomycin. The present four experiments investigated the effects of diets containing salinomycin at 0, 2.2, 5.5, 11, and 22 mg/kg and vomitoxin at 0, 2.2, and 4.4 mg/kg. A factorial design with vomitoxin at 0 and 4.4 mg/kg and salinomycin at 0 and 22 mg/kg was used in Experiment 4. Poults fed the suspect commercial diet had significantly lower feed consumption and higher motality than poults fed a control diet (P less than .05). Poults (0 to 3 wk of age) fed diets containing vomitoxin (4.4 mg/kg), salinomycin (22 mg/kg), or both showed no significant decrease in feed consumption, body weight gain, or viability.