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The present study was designed to investigate the histochemical developmental changes of the proventriculus at pre-hatching and post-hatching in the northern bobwhite quail at periods 11- and 15-days pre-hatching in addition to 14- and 21-days post-hatching. The proventriculus composed of four tunics is tunica mucosa, tunica sub-mucosa, tunica muscularis, and tunica serosa. The tunica mucosa was lined with simple columnar epithelium and the height of epithelium increases with the age also the thickness of the mucosa, the tunica submucosa filled with proventricular glands at 14- and 21-day post-hatch and the gland was height in diameters while in 11- and 15-day pre-hatch the gland less in diameter and the sub mucosa does not fill with the gland. Tunica muscularis was thicker in post-hatch than in pre-hatch, 11- and 15- day pre-hatch composed of a thin inner circular layer and thick outer longitudinal layer but in 14- and 21-day post-hatch the tunica muscularis was composed of a thin inner and outer circular layer and thick middle longitudinal layer. The mucosa and proventriculus glands give a positive reaction for Alcian blue stain and a weak to moderate reaction for periodic acid Schiff stain at pre-hatch, while at post-hatch the mucosa gives a positive reaction for Alcian blue stain and a negative reaction for periodic acid Schiff stain and the proventricular glands give a positive reaction for Alcian blue and periodic acid Schiff stains.

The effects of flock size of European starlings (Sturnus vulgaris) was experimentally manipulated to assess the potential of influenza A virus (IAV; H4N6) transmission from a flocking passerine to bobwhite quail (Colinus virginianus) through shared food and water resources to mimic starling intrusions into free‐range and backyard poultry operations. Of the three starling flock sizes tested (n = 30, n = 20 and n = 10), all successfully transmitted the virus to all or most of the quail in each animal room (6/6, 6/6 and 5/6) by the end of the experimental period, as determined by seroconversion and/or viral RNA shedding. Although starlings have been shown to be inconsistent shedders of IAVs and when they do replicate and subsequently shed virus they typically do so at low to moderate levels, this study has provided evidence that relatively small flocks (i.e., 10 or possibly a smaller number) of this species can collectively transmit the virus to a highly susceptible gallinaceous bird species. Future work should assess if starlings can transmit IAVs to additional poultry species commonly found in backyard or free‐range settings. [ABSTRACT FROM AUTHOR]

A captive-bred Bobwhite Quail (Colinus virginianus) ranch in southern Utah, US experienced high mortality rates in the late summer and fall of 2012. Nine juvenile birds were necropsied at the Utah Veterinary Diagnostic Laboratory. Gross lesions included pale skeletal muscle with multifocal hemorrhages and petechiae in the air sacs and serosal surfaces of most organs. Histologically there was moderate to severe, multifocal, degenerative myositis with intramyofiber schizonts and minimal lymphoplasmacytic infiltrates in the proventriculus, ventriculus, heart, and skeletal muscle. There was also moderate fibrinoid to heterophilic vasculitis in multiple organs with vascular intraendothelial or intravascular merozoites and scattered thrombosis. In the liver and spleen there were multiple degenerative schizonts that had ruptured. Blood smears from three of the birds were stained with Wright-Giemsa stain and examined at a referral laboratory. Although the blood cells were deteriorated (postmortem artifact), life stages (exact stages not specified) consistent with Haemoproteus spp. were identified in erythrocytes. Polymerase chain reaction done on pooled tissues from two birds produced an amplicon in both pooled samples, and direct sequencing confirmed the presence of 533 base pairs of a Haemoproteus sp. in the subgenus Parahaemoproteus. The identification of Parahaemoproteus spp. in quail in southern Utah implies that appropriate Culicoides spp. vectors are present in the state and that there is potential risk to other birds such as zoo and aviary populations, wild turkeys, and other game birds. [ABSTRACT FROM AUTHOR]

Hematology and its regulation in developing birds have been primarily investigated in response to relatively short-term environmental challenges in the embryo. Yet, whether any changes induced in the embryo persist into adulthood as a hematological form of “fetal programming” is unknown. We hypothesized that: 1) chronic as opposed to acute hypoxic incubation will alter hematological respiratory variables in embryos of bobwhite quail ( Colinus virginianus ), and 2) alterations first appearing in the embryo will persist into hatchlings through into adulthood. To test these hypotheses, we first developed an embryo-to-adult profile of normal hematological development by measuring hematocrit (Hct), red blood cell concentration ([RBC]), hemoglobin concentration ([Hb]), mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration, as well plasma osmolality. Hct, [RBC] and [Hb] in normoxic-incubated birds (controls) steadily increased from ~22%, ~1.6 × 10 6  μL −1 and ~7 g% in day 12 embryos to almost double the values at maturity in adult birds. Both cohort and sex affected hematology of normoxic-incubated birds. A second population, incubated from day 0 (d0) in 15% O 2 , surprisingly revealed little or no significant difference from controls in hematology in embryos. In hatchlings and adults, hypoxic incubation caused no significant modification to any variables. Compared to major hematological effects caused by hypoxic incubation in chickens, the hematology of the bobwhite quail embryo appears to be minimally affected by hypoxic incubation, with very few effects induced during hypoxic incubation actually persisting into adulthood. [ABSTRACT FROM AUTHOR]

To determine potential intermediate hosts of Oxyspirura petrowi, a common nematode eyeworm of wild gallinaceous birds, various arthropod species including red harvester ants, beetles, wood cockroaches, crickets, grasshoppers, katydids, and desert termites were screened for the presence of O. petrowi using specific polymerase chain reaction (PCR) primers targeting the internal transcribed spacer 2 region (ITS2) of the eyeworm ribosomal deoxyribonucleic acid (rDNA). This is the first study to investigate the intermediate hosts of O. petrowi utilizing molecular techniques. We determined 38% (13/34) of the cockroaches, 27% (3/11) of the crickets, and 23% (68/289) of the grasshoppers which were positive for O. petrowi. Identifying potential intermediate hosts of O. petrowi is essential to better understanding the epizoology of the eyeworm’s transmission mechanics and to controlling infections in wild gallinaceous birds. [ABSTRACT FROM AUTHOR]

The ex vivo culture of avian embryos is a technique for the long-term culturing of embryos outside of their own shell and shell membrane. It allows easy access to the developing embryos and embryo manipulation. The two-step system is widely applied when the culture is performed after oviposition. Japanese quail as well as bobwhite quail are used as models for avian safety assessment as recommended by the Organisation for Economic Co-operation and Development (OECD) guidelines. However, biological studies on the bobwhite quail have been more limited than those on the Japanese quail. We have developed a more simplified ex vivo culture protocol for the two species of quail embryos from the blastoderm stage through to hatching using a single surrogate eggshell. Hatchabilities of 31% and 27% were obtained in bobwhite quail and Japanese quail embryos, respectively. The simple system described in the present study is an easy and acceptable procedure.

In a study conducted on a total of 30 males and females of Bobwhite quail, Colinus virginianus species, was monitored to determine the average results at slaughter at 70 weeks of age. As a result of the research carried out was determined an average body weight similar in the two sexes, of 245.00 ± 2.35 g/head in the female, while in male was of 250.00 ± 2.65 g/head, and the weight of the carcase after evisceration was 170.00 ± 2.35 g for females and of 167.00 ± 2.05 g in males. The yield was of 68.16 ± 1.75% in females and of 68.00 ± 1.25% in males, the difference was not significant. The average breast weight was of 87.00 ± 1.05 g in females and less with 2.3% in males, of 85.00 ± 1.13 g, the difference being statistically not ensured. The average proportion of the chest was 52.10 ± 1.55% in females and of 50.00 ± 1.05% in males. [ABSTRACT FROM AUTHOR]

Quail are divided phylogenetically into two groups, Old World quail and New World quail. Old World quail, such as the Japanese quail (Coturnix japonica), belong to the Phasianidae and distributed in the Palaearctic region (Europe, North Africa, and Asia), whereas New World quail, such as the bobwhite quail (Colinus virginianus), belong to the Odontophoridae and are restricted to North and South America. Both the bobwhite quail and the Japanese quail are used as models for avian safety assessment as recommended by the Organisation for Economic Co-operation and Development (OECD) guidelines. However, biological studies on the bobwhite quail have been limited compared with those on the Japanese quail. We have therefore now developed an ex vivo culture protocol for bobwhite quail embryos from the blastoderm stage through hatching. Of the various culture conditions examined in the present study, a good hatching rate (39%) was obtained when the embryos were cultured ex vivo in a two-step procedure. Unincubated embryos (with egg yolk) were first cultured inside the shell of a Japanese quail eggs (11.5 to 13.0 g whole egg weight) together with chicken thin albumen for 63 to 65 h and were then transferred to the shell of a small-sized chicken egg (38 g whole egg weight) until hatching. This ex vivo culture system should provide to be widely applicable to the maintenance and generation of manipulated birds for basic and applied studies on the bobwhite quail.

ABSTRACT Avian eggs contain maternally derived hormones, including testosterone and progesterone. Little is currently known about the effects of these hormones on early behavioral development. We assessed the effects of elevated levels of progesterone levels on prenatal perceptual learning and postnatal emotional reactivity in Northern bobwhite quail. Prior to incubation, eggs received an injection of either progesterone (P) or oil vehicle (V). In P eggs, levels of progesterone were elevated two standard deviations above the mean based on ELISA analysis of progesterone yolk concentrations from a previous study. A third group of eggs served as controls and received no injection (C). Chicks hatched from P eggs displayed elevated levels of emotional reactivity compared to V and C chicks in a tonic immobility task and a hole-in-the-wall emergence task. Chicks from P eggs also failed to demonstrate a preference for a familiarized bobwhite maternal call that had been presented prenatally. In contrast, the V and C chicks demonstrated a significant preference for the familiarized maternal call following hatching, indicating prenatal auditory learning. Our results are consistent with previous findings from precocial birds demonstrating that hormones of maternal origin can influence prenatal perceptual learning as well as emotional reactivity in the period following hatching. © 2015 Wiley Periodicals, Inc. Dev Psychobiol 57: 255-262, 2015. [ABSTRACT FROM AUTHOR]

With the advent of the usage of primary fibroblasts in comparative and evolutionary biology, it is important for researchers to know the extent to which cells might be altered during the culturing process and how much species might differ in response to cell culture. We compared early changes in cell size and lipid composition of primary dermal fibroblasts grown at physiologically relevant oxygen concentrations (5% O2) from wild-caught species of birds. Fibroblasts from American Robins ( Turdus migratorius L., 1766) and Bobwhite Quails ( Colinus virginianus (L., 1758)) increased in size early in the culture process and cells from all five species of wild-caught birds exhibited changes in lipid-class composition. The two most common phospholipids, phosphatidylcholine and phosphatidylethanolamine, increased in concentration in all species between early passages and later passages of fibroblasts. Some less abundant lipid species, such as cardiolipin and sphingomyelin, exhibited similar concentrations in all three passages that we measured. Other lipid classes, such as cholesterol, increased in some species in later passages and decreased in others. Although results may vary with cell-culture conditions, this study points to a need for researchers comparing multiple species to take precautions when using cell culture, such as experimenting on the earliest possible passage of cells. [ABSTRACT FROM AUTHOR]

Early warning systems of extinction thresholds have been developed for and tested in microcosm experiments, but have not been applied to populations of wild animals. We used state-space population models and a statistical indicator to detect a transcritical bifurcation extinction threshold in a population of bobwhite quail ( Colinus virginianus) located in an agricultural region experiencing habitat deterioration and loss. The extinction threshold was detectible using two independent data sets. We compared predictions from state-space population models to predictions from a statistical indicator and found that predictions were corroborated. Using state-space population models, we estimated that our study population crossed the extinction threshold in 2010 (2002-2036; 95 % confidence intervals [CI]) using the whistle count (WC) data set and in 2008 (1999-2064; 95 % CI) using the Breeding Bird Survey (BBS) data. With the statistical indicator, we estimated that the extinction threshold will be crossed in 2018 (2004-2031; 95 % CI) using the WC data and will be crossed in 2012 (2006-2018; 95 % CI) using the BBS data. We expect extinction in our study population soon after crossing the extinction threshold, but the time to extinction and potential reversibility of the threshold are unknown. Our results suggest that neither small nor decreasing population size will warn of the transcritical bifurcation extinction threshold. We suggest that managers of wildlife populations in regions experiencing land use change should try to predict extinction thresholds and make management decisions to ensure the persistence of the species. [ABSTRACT FROM AUTHOR]

This study describes the first isolation of H9N2 avian influenza virus (AIV) from commercial bobwhite quail ( Colinus virginianus) in Egypt. Infected birds showed neither clinical signs nor mortality. Virus isolation and real-time reverse transcription polymerase chain reaction confirmed the presence of the H9N2 virus in cloacal swab samples collected at 35 days of age and the absence of other AIV subtypes, including H5 and H7. The hemagglutinin and neuraminidase genes of the isolated virus showed 99.1% and 98.2% nucleotide identity and 97.3% and 100% amino acid identity, respectively, to those of H9N2 viruses currently circulating in poultry in the Middle East. Phylogenetically, the Egyptian H9N2 virus was closely related to viruses of the G1-like lineage isolated from neighbouring countries, indicating possible epidemiological links. [ABSTRACT FROM AUTHOR]

Abstract: Arthropod sampling via periodic direct bird examination and regular light trapping was conducted between June 2000 and October 2002 to survey for potential vectors of Haemoproteus lophortyx to nonnative, captive-raised bobwhite quail (Colinus virginianus) in northern California, USA. Examination of individual bobwhite quail (from 5 weeks of age through adult, total n =76) was conducted on several dates during the transmission period (June–October). No ectoparasites, including hippoboscid flies (reported as Haemoproteus vectors to wild quail in early literature), were collected from the birds. Trapping with ultraviolet light suction traps near the quail revealed nine species of biting midges (Culicoides spp.). Of these, 94% were C. bottimeri, which was abundant near the birds, and 65% of collected C. bottimeri were engorged with blood. C. bottimeri adult activity began in late-April, slightly before the onset of disease in the quail. Activity peaked between July and late-September, coincident with maximum reported transmission, and adult activity ceased by early-November. Nonengorged C. bottimeri had a parity rate of 43.6% overall, suggesting excellent survival for biological transmission of a pathogen like H. lophortyx. A controlled study was done injecting a macerated slurry of pooled, nonengorged, wild-caught C. bottimeri into the peritoneum of 1-day-old bobwhite quail hatchlings held in insect-proof containers. Blood smears 13–19 days later confirmed H. lophortyx infection in zero controls but all insect-injected quail. Biting midges, especially C. bottimeri, transmit H. lophortyx to captive quail and probably are the dominant vector to native California quail (Callipepla californica) as well. [Copyright &y& Elsevier]

This study examined the effects of prenatal visual stimulation on bobwhite quail embryos' growth and heart rate. No differences in growth rate were found between embryos exposed to visual stimulation during the late prenatal period and control embryos. Embryos exposed to visual stimulation throughout incubation maintained lower heart rates in response to visual stimulation than did naïve embryos. In a subsequent experiment, naïve embryos that underwent an egg-opening procedure exhibited heart rates that were lower than embryos measured in intact eggshells. Embryos in opened eggs maintained lower heart rates than comparison embryos across time; however, a less invasive egg-opening procedure led to a quicker heart rate recovery than did a more invasive egg-opening procedure. These findings indicate that prenatal heart rate responses may be mediated by multiple features of the organism's developmental context, including intensity and duration of sensory stimulation. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 315–324, 2006. [ABSTRACT FROM AUTHOR]

This study evaluated the toxicity effects of chlorpyrifos on bobwhite quail (Colinus virginianus) kept in 27 field-exposed large pens arranged over turf in a randomized block design with nine blocks of three pens (16 adult birds per pen). Nine pens were treated with one application of 3.4 kg active ingredient (ai) per hectare followed by a second 3.4-kg ai/ha application 2 weeks later, nine pens with one 6.7-kg ai/ha application, and nine pens with formulation blank. In addition, the seed fed to the birds in the two chemically treated pens was also treated with chlorpyrifos. Mean residue in the grass samples from the first 3.4-kg treatment pens ranged from 306±95 ppm on day 0 to 18±8 ppm on day 14 after treatment. The second 3.4-kg ai/ha treatment grass residues ranged from 361±167 ppm on day 0 to 38±24 ppm on day 14 after treatment. Grass residues from the 6.7-kg treatment pens ranged from 903±310 ppm on day 0 to 9±8 ppm on day 30 after treatment. Half-lives were ∼2 days and 10 days for grass and seeds, respectively. Whereas the incidence of behavioral deficits was significantly (P=0.0156) higher in the 6.7-kg pens (five females, one male), two of the females could have been the same bird because they were both seen in the same pen on days 23 and 24 after treatment. There was no significant difference in mortality, brain acetylcholinesterase activity, or any other measured parameter among any of the treatments. We conclude that application of chlorpyrifos to turf at 3.4 and 6.7 kg ai/ha is not expected to have chronic deleterious effects on populations of bobwhite quail grazing on treated grass or seeds, provided there is an abundant supply of seeds for the quail to eat. [Copyright &y& Elsevier]

Presents abstracts of several studies about environment, management-breeder and incubation. "Examining if the Hole Created by Egg Injection Improves Late Embryonic Survival," by B. L. Kumpula and G. M. Fasenko; "Effect of Hatch Pull Time, Protein and Methionine on Bobwhite Quail Performance," by J. P. Blake, J. B. Hess, and W. D. Berry; "Influence of Light Intensity and Handling on Live and Processing Performance of Male Broilers," by R. J. Lien, J. B. Hess, S. R. McKee, B. A. McCrea, and S. F. Bilgili; "Impact of Genotype, Growth Profile and Photostimulation Age on the Reproductive Efficiency of Female Broiler Breeders," by R. A. Renema, M. J. Zuidhof, and F. E. Robinson.

Presents abstracts of several studies about environment, management-breeder and incubation. "Examining if the Hole Created by Egg Injection Improves Late Embryonic Survival," by B. L. Kumpula and G. M. Fasenko; "Effect of Hatch Pull Time, Protein and Methionine on Bobwhite Quail Performance," by J. P. Blake, J. B. Hess, and W. D. Berry; "Influence of Light Intensity and Handling on Live and Processing Performance of Male Broilers," by R. J. Lien, J. B. Hess, S. R. McKee, B. A. McCrea, and S. F. Bilgili; "Impact of Genotype, Growth Profile and Photostimulation Age on the Reproductive Efficiency of Female Broiler Breeders," by R. A. Renema, M. J. Zuidhof, and F. E. Robinson.

Presents abstracts of several studies about environment, management-breeder and incubation. "Examining if the Hole Created by Egg Injection Improves Late Embryonic Survival," by B. L. Kumpula and G. M. Fasenko; "Effect of Hatch Pull Time, Protein and Methionine on Bobwhite Quail Performance," by J. P. Blake, J. B. Hess, and W. D. Berry; "Influence of Light Intensity and Handling on Live and Processing Performance of Male Broilers," by R. J. Lien, J. B. Hess, S. R. McKee, B. A. McCrea, and S. F. Bilgili; "Impact of Genotype, Growth Profile and Photostimulation Age on the Reproductive Efficiency of Female Broiler Breeders," by R. A. Renema, M. J. Zuidhof, and F. E. Robinson.

Most biomonitoring studies that have investigated the relationship between fluctuating asymmetry (FA) and anthropogenic stressors have measured organisms from polluted ecosystems and compared them to organisms at reference sites. What has received little attention is whether FA follows a dose–response relationship with stress, a key criterion of a useful biomarker. Using chicks from currently mandated avian reproductive tests we tested whether a composite index of FA (FAC), was related to the dose or duration of exposure of their parents to one of four different herbicides, and if FAC was indeed a more sensitive marker of stress than standard reproductive endpoints measured from this test. We found no consistent relationship between FAC and dose or duration of herbicide exposure in any of the four studies. Exposure to one of the four pesticides did result in significant reproductive toxicity but this was not accompanied or foreshadowed by higher levels of FAC. Our results do not support the hypothesis that FA is a reliable general biomarker of pesticide exposure. [Copyright &y& Elsevier]

Many environmental toxins have been shown to suppress the immune system across taxa. The foreign red blood cell (RBC) challenge is an important part of a complement of tests used to assess immunocompetence in the laboratory because it can assess an individual’s humoral response without impacting its health. This challenge is used commonly across species and measures antibody titers in response to an intraperitoneal, intravenous, or subcutaneous injection of foreign RBCs. Determination of the best appropriate foreign RBC challenge is therefore important when designing tests for evaluation of humoral responses. The northern bobwhite (Colinus virginianus) is a commonly used species for avian toxicity tests, however little is known about the relative sensitivities of its humoral responses to foreign erythrocytes. In this pilot study, we exposed adult quail to intravenous injections of 5% solutions of sheep, rat, rabbit, bovine, or chicken erythrocytes and performed antibody titers [hemagglutination assay for total immunoglobulin (Ig), IgG, and IgM] for primary and secondary responses. Although the bobwhites appeared to respond strongly to rat RBCs, high variability in responses were observed among individuals. Chicken RBCs elicited the poorest responses for both primary and secondary challenges. Sheep and bovine RBCs were adequate antigens for this test in bobwhites. We found that rabbit erythrocytes elicited the strongest responses with the least amount of variability between individuals. Rabbit RBCs, therefore, appear to be the ideal antigen for this test of the humoral response in this species. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of isolated enterococcus facuim from intestine of Coracias Garrulus (EF) and lactofeed with two methods of spraying and drinking on performance, carcass characteristics, blood parameters, immune response, ceca microflora and jejunal morphology of BobWhite quail were done. A total of 420 chicks were arranged into 35 experimental pen with 7 treatments in a completely randomized design. The treatments were the control, the spraying, the drinking and spraying+drinking of enterococcus facuim, and the spraying, the drinking and the spraying+drinking of Lactofeed groups. A solution of 1011 CFU was used on days 1, 10 and 24 of age for spraying and drinking. Adding the same spraying and drinking EF or lactofeed reduced FCR (2.71 vs. 2.51) and increased body weight (395.67 vs. 307.88) in quail (P<0.05). The lowest abdominal fat percentage (0.725 vs. 23.14%) and highest weight of bursa of fabricus (0.78 vs. 0.62) in the quail = was belonged to the combination of spraying and drinking EF group. Lactofeed or EF reduced the concentration of cholesterol (249 vs. 342 mg/dl), LDL (211 vs. 148 mg/dl), triglyceride (173 vs. 268 mg/dl) and aspartate aminotransferase enzyme activity (256 vs. 192 U/L), but HDL concentration enhanced (96.16 vs. 67.44 mg/dl). In both methods of spraying and drinking, the EF improved immune responses to SRBC as compared to the control (9.33 vs 6.66) (P<0.05). Both of Lactofeed and EF improved the lactobacilli population of the ceca and morphology of jejunum. Therefore, the addition of enterococcus facuim isolates (EF) and lactofeed with the method of combination spraying and drinking may improve the performance, ceca flora, jejunum morphology, immune response and decreases the abdominal fat, blood lipids. [ABSTRACT FROM AUTHOR]

We used gray-tailed voles (Microtus canicaudus) and northern bobwhite quail (Colinus virginianus) as experimental model species to field test whether small mammals and birds respond differently to equivalent concentrations of a pesticide applied in granular and flowable formulations. In mid-May 1998, we placed voles into 15, 0.2-ha enclosuresplanted with a mixture of pasture grasses. In mid-July, we placed quail into the same enclosures with the voles. In late July, we appliedthe organophosphorus insecticide diazinon in five treatments; a control (all habitats sprayed with water), liquid formulation of diazinonat 0.55 kg/ha, liquid formulation of diazinon at 1.11 kg/ha, broadcast of granular diazinon at 1.11 kg/ha, and broadcast of granular diazinon at 2.22 kg/ha. The diazinon treatment in liquid and granular formulations did not depress population size or growth rate, or survivalrate of voles. We found a significant difference in the survival rate of the quail between the controls and treatments; granular diazinoncaused a measurable decline of quail survival, whereas the liquid application at an equivalent rate did not significantly affect quail survival. Analysis of our results suggests that ground-feeding birds are more susceptible to granular insecticides than flowable applications, but voles were not susceptible to either formulation at the rate we used. [ABSTRACT FROM AUTHOR]

Separate, 28-day, subchronic studies of strychnine dietary toxicity were conducted using northern bobwhite quail (Colinus virginianus) and mallard ducks (Anas platyrhynchos). Five groups (five males five females/group) of 29-week-old quail were fed Purina(r) Game Bird Breeder Layena(r) diets containing mean (+/-SD) 484.2 (+/-17.0), 972.6 (+/-54.0), 1,870.8 (+/-176.1), 3,516.7 (+/-68.0), and 6,083.3 (+/-269.6) mug/g strychnine; whereas five groups of 27-week-old mallards (five males five females/group) were fed similar diets containing mean (+/-SD) 18.8 (+/-1.3), 91.1 (+/-27.3), 235.0 (+/-33.8), 484.2 (+/-17.0), and 972.6 (+/-54.0) mug/g strychnine. Separate 'vehicle control' (0.0 mug/g strychnine) groups (five males, five females/group) were included in each study. Strychnine toxicity was much less pronounced in quail; no observed effect concentrations (NOECs) were 972.6 (+/-54.0) and 91.1 (+/-27.3) mug/g strychnine for quail and ducks, respectively. Several possible explanations for the species effects are offered, and some practical issues affecting the conduct of long-term, dietary toxicity studies are discussed. [ABSTRACT FROM AUTHOR]