Acute exposure to hyperthermic oscillating temperatures during pre-incubation influences northern bobwhite development, hatching, and survival.

Temperature extremes alter development, growth, hatching, and survival of eggs of ground-nesting birds, particularly during pre-incubation (egg laying) when eggs are left unattended and exposed to the environment for days or weeks before parental incubation begins. The northern bobwhite quail is a ground-nesting bird whose eggs experience high temperatures (≥45° C) during pre-incubation. It is known that chronic high temperatures during pre-incubation alter development and reduce hatching and survival of bobwhite eggs, but it is not known if acute doses of high temperatures during pre-incubation have the same effect. In this study, the 12-d pre-incubation period was divided into thirds. Fresh bobwhite eggs were exposed to either a commercial holding temperature for all 12 d (serving as a control), or a high oscillating temperature regimen for 4 d (one third of pre-incubation) either in the early, middle, or late third of pre-incubation, with a low oscillating temperature regimen during the remaining 8 d. The timing of acute exposure to high oscillating temperatures significantly affected bobwhite development. Eggs exposed in the first 2/3 of pre-incubation developed twice as much as eggs exposed late in pre-incubation, even though all eggs received the same amount of heating degree-hours. Thus, a critical window of thermal susceptibility exists for developing northern bobwhites. Acute exposure to high oscillating temperatures resulted in reduced hatchling mass, hatching success, survival, and compromised hatching synchrony. Thus, acute hyperthermic nest temperatures during pre-incubation could result in the observed reductions in the percentage of juveniles in natural populations during hot and droughty years.

Hematology from embryo to adult in the bobwhite quail (Colinus virginianus): Differential effects in the adult of clutch, sex and hypoxic incubation.

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 × 106 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% O2, 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.

The intersensory redundancy hypothesis: Extending the principle of unimodal facilitation to prenatal development.

Selective attention to different properties of stimulation provides the foundation for perception, learning, and memory. The Intersensory Redundancy Hypothesis (IRH) proposes that early in development information presented redundantly across two or more modalities (multimodal) selectively recruits attention to and enhances perceptual learning of amodal properties, whereas information presented to a single sense modality (unimodal) enhances perceptual learning of modality-specific properties. The present study is the first to assess this principle of unimodal facilitation in non-human animals in prenatal development. We assessed bobwhite quail embryos' prenatal detection of pitch, a modality-specific property, under conditions of unimodal and bimodal (synchronous or asynchronous) exposure. Chicks exposed to prenatal unimodal auditory stimulation or asynchronous bimodal (audiovisual) stimulation preferred the familiarized maternal call over a novel pitch-modified maternal call following hatching, whereas chicks exposed to redundant (synchronous) audiovisual stimulation failed to prefer the familiar call over the pitch-modified call. These results provide further evidence that selective attention is recruited to specific stimulus properties of events in early development and that these biases are evident even during the prenatal period.

Coordinated movement is influenced by prenatal light experience in bobwhite quail chicks (Colinus virginianus).

Sensory-motor development begins early during embryogenesis and is influenced by sensory experience. Little is known about the prenatal factors that influence the development of motor coordination. Here we investigated whether and to what extent prenatal light experience can influence the development of motor coordination in bobwhite quail hatchlings. Quail embryos were incubated under four light conditions: no light (dark), 2h of total light (2HR), 6h of total light (6HR), and diffused sunlight (controls). Hatchlings were video recording walking down a runway at three developmental ages (12, 24, and 48h). Videos were assessed for forward locomotion, a measurement of motor coordination, falls, a measurement of motor instability, and motivation to complete the task. We anticipated a linear decline of coordination with a reduction in prenatal light experience and improved coordination with age. Furthermore, as motor coordination becomes more laborious we anticipated motivation to complete the task would decline. However, our findings revealed hatchlings did not uniformly improve with age as expected, nor did the reduction of light result in a linear reduction in motor coordination. Instead, we found a more complex relationship with 6HR and 2HR hatchlings showing distinct patterns of stability and instability. Similarly, we found a reduction in motivation within the 6HR light condition. It appears that prenatal light exposure influences the development of postnatal motor coordination and we discuss these finding in light of neurodevelopmental processes influenced by light experience.

The effects of neonicotinoid exposure on embryonic development and organ mass in northern bobwhite quail (Colinus virginianus).

Since their emergence in the early 1990s, neonicotinoid use has increased exponentially to make them the world's most prevalent insecticides. Although there has been considerable research concerning the lethality of neonicotinoids, their sub-lethal and developmental effects are still being explored, especially with regard to non-mammalian species. The goal of this research was to investigate the effects of the neonicotinoid imidacloprid on the morphological and physiological development of northern bobwhite quail (Colinus virginianus). Bobwhite eggs (n=390) were injected with imidacloprid concentrations of 0 (sham), 10, 50, 100, and 150mg/kg of egg mass, which was administered at day 0 (pre-incubation), 3, 6, 9, or 12 of growth. Embryos were dissected, weighed, staged, and examined for any overt structural deformities after 19days of incubation. The mass of the embryonic heart, liver, lungs and kidneys was also recorded. The majority of treatments produced no discernible differences in embryo morphology; however, in some instances, embryos were subject to increased frequency of anatomical deformity and altered organ masses. Some impacts were more pronounced in specific dosing periods, implying that there may be critical windows of development when embryos are more susceptible to neonicotinoid exposure. This investigation suggests that imidacloprid has the potential to impact bobwhite quail embryonic development and chick survival.

Dietary toxicity of soluble and insoluble molybdenum to northern bobwhite quail (Colinus virginianus).

Limited data are available on the effects of molybdenum (Mo) on avian wildlife, which impairs evaluation of ecological exposure and risk. While Mo is an essential trace nutrient in birds, little is known of its toxicity to birds exposed to molybdenum disulfide (MoS2), the predominant form found in molybdenite ore. The chemical form and bioavailability of Mo is important in determining its toxicity. Avian toxicity tests typically involve a soluble form of Mo, such as sodium molybdate dihydrate (SMD, Na2MoO4·2H2O); however MoS2 is generally insoluble, with low bioaccessibility under most environmental conditions. The current study monitored survival and general health (body weight and food consumption) of 9-day old northern bobwhite exposed to soluble Mo (SMD) and ore-related Mo (MoS2) in their diet for 30 days. Toxicity and bioavailability (e.g. tissue distribution) of the two Mo forms were compared. Histopathology evaluations and serum, kidney, liver, and bone tissue sample analyses were conducted. Copper, a nutrient integrally associated with Mo toxicity, was also measured in the diet and tissue. No treatment-related mortality occurred and no treatment-related lesions were recorded for either Mo form. Tissue analyses detected increased Mo concentrations in serum, kidney, liver, and bone tissues following exposure to SMD, with decreasing concentrations following a post-exposure period. For the soluble form, a No-Observed-Adverse-Effect Concentration (NOAEC) of 1200 mg Mo as SMD/kg feed (134 mg SMD/kg body weight/day) was identified based on body weight and food consumption. No adverse effects were observed in birds exposed to MoS2 at the maximum dose of 5000 mg MoS2/kg feed (545 mg MoS2/kg body weight/day). These results show that effects associated with MoS2, the more environmentally prevalent and less bioavailable Mo form, are much less than those observed for SMD. These data should support more realistic representations of exposure and risks to avian receptors from environmental Mo.

Características de carcaça de codornas de corte EV1 alimentadas com diferentes níveis de metionina+cistina total / Carcass traits of EV1 quail strain fed different methionine+cystine level diets

O peso e o rendimento das carcaças de codornas de corte da linhagem EV1 foram avaliados no 35° dia de idade em delineamento experimental inteiramente ao acaso, com os tratamentos consistidos de um fatorial 2 x 6, ou seja, dois sexos e seis níveis de metionina+cistina totais (0,73; 0,79; 0,85; 0,91; 0,97 e 1,03%), quatro repetições e 12 aves por unidade experimental. Foram avaliados peso corporal, peso e rendimento de carcaça, peito, coxa, asas, vísceras comestíveis e gordura abdominal. Não houve efeito da interação sexo x nível de metionina das dietas para nenhuma das variáveis analisadas. Houve efeito quadrático dos níveis de metionina+cistina sobre peso corporal, carcaça, peito, coxa, asa e coração, com pontos de máximo em 0,93% para peso corporal, carcaça, peito e coxa; 0,90% para peso de asa e 0,92% para peso de coração. O peso de fígado aumentou de forma linear à medida que foram aumentados os níveis de metionina+cistina das dietas. Os níveis de metionina+cistina da dieta influenciaram de forma quadrática nos rendimentos de peito e asas, com pontos de máximo estimados para codornas alimentadas com dietas contendo 0,96% e 0,98% de metionina+cistina, respectivamente. O maior rendimento de moela foi obtido nas codornas alimentadas com 0,73% de metionina+cistina. O peso corporal de carcaça, peito, coxa, asa, fígado, moela e o rendimento de fígado nas fêmeas foram maiores que nos machos. A exigência de metionina+cistina para pesos de carcaça e peito é 0,93%, e para rendimento de peito 0,96%...

Carcass weight and yield of European quail strain EV1 were evaluated at 35 days of age in a completely randomized experimental design, with the treatments consisting of a 2 x 6 factorial combination, two sexes and six different methionine+cystine levels of diets (.73; .79; .85; .91; .97 and 1.03%), with four replicates and 12 quails per experimental unit. Body weight, weights and yields of carcass, breast, thigh, wing and, edible giblets and abdominal fat were recorded. Significant and quadratic effect of methionine+cystine level on body weight, weights of carcass, breast, thigh and heart were observed with estimated maximum of body weight and weights of carcass, breast and thigh for quails fed .93% methionine+cystine diets, .90% for wing weight and .92% for heart weight. Increasing and linear response of liver weight to methionine+cystine level of diet was estimated while breast and wing yields showed quadratic responses with estimated maximum for quails fed .96% and .98% methionine+cystine level diets. Higher gizzard yield was observed for quails fed .73% diets. Higher body weight, and weights of carcass, thigh, wing, liver, gizzard and liver yields were estimated for females. Methionine+cystine requirement for quail carcass and breast weights is .93% and for breast yield .96%...

Acute toxicity of diphacinone in Northern bobwhite: effects on survival and blood clotting.

The anticoagulant rodenticide diphacinone was slightly toxic (acute oral LD50 2014 mg/kg) to Northern bobwhite (Colinus virginianus) in a 14-day acute toxicity trial. Precise and sensitive assays of blood clotting (prothrombin time, Russell's Viper venom time, and thrombin clotting time) were adapted for use in quail, and this combination of assays is recommended to measure the effects of anticoagulant rodenticides. A single oral sublethal dose of diphacinone (434 mg/kg body weight) prolonged clotting time at 48 h post-dose compared to controls. At 783 mg/kg (approximate LD02), clotting time was prolonged at both 24 and 48 h post-dose. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and was detected before overt signs of toxicity were apparent at the greatest dosages (2868 and 3666 mg/kg) in the acute toxicity trial. These clotting time assays and toxicity data will assist in the development of a pharmacodynamic model to predict toxicity, and also facilitate rodenticide hazard and risk assessments in avian species.

Bigger brains cycle faster before neurogenesis begins: a comparison of brain development between chickens and bobwhite quail.

The chicken brain is more than twice as big as the bobwhite quail brain in adulthood. To determine how this species difference in brain size emerges during development, we examined whether differences in neurogenesis timing or cell cycle rates account for the disparity in brain size between chickens and quail. Specifically, we examined the timing of neural events (e.g. neurogenesis onset) from Nissl-stained sections of chicken and quail embryos. We estimated brain cell cycle rates using cumulative bromodeoxyuridine labelling in chickens and quail at embryonic day (ED) 2 and at ED5. We report that the timing of neural events is highly conserved between chickens and quail, once time is expressed as a percentage of overall incubation period. In absolute time, neurogenesis begins earlier in chickens than in quail. Therefore, neural event timing cannot account for the expansion of the chicken brain relative to the quail brain. Cell cycle rates are also similar between the two species at ED5. However, at ED2, before neurogenesis onset, brain cells cycle faster in chickens than in quail. These data indicate that chickens have a larger brain than bobwhite quail mainly because of species differences in cell cycle rates during early stages of embryonic development.

Unsuitability of the northern bobwhite as a model species for the assessment of reproductive behavior in toxicological studies.

The northern bobwhite (Colinus virginianus) is used in numerous wildlife toxicity studies, however no published reports could be located that mention the measurement of reproductive behavior in this species. Changes in reproductive behavior can be potentially more sensitive to environmental contaminant exposures and less resilient than more traditional physiological responses. Male bobwhite copulatory behaviors were measured similarly to those that are well established for use in Japanese quail (Coturnix japonica). Time to initiate mating, time to achieve a successful copulation, the number of mating attempts, and the number of successful copulations were recorded daily for four consecutive days over a period of 3 min for each male/female pair of birds per day. When females were introduced to male cages, males were more occupied with shows of aggression towards neighboring males than attempts to mate with the female sharing their space. Only one male successfully mated with a female over the entire 4 days of the test. Future attempts at assessing reproductive behavior in this species may be more successful if birds are separated from the rest of the group when paired. The Japanese quail seems to be a more appropriate species for overall reproductive tests due to: willingness of males to copulate in the presence of other males, consistent egg laying ability, and the short time required for embryonic development and reproductive maturity.

Stimulus contingency and the malleability of species-typical auditory preferences in Northern bobwhite (Colinus virginianus) hatchlings.

Precocial avian hatchlings are typically highly social and show strong species-typical preferences for the maternal calls of their own species. The influence of social contingencies on the acquisition of species-specific preferences has, however, largely been neglected. We found that exposing bobwhite (BW) quail chicks to a Japanese quail (JQ) call contingent on their own vocalizations for 5 min was sufficient to eliminate their species-typical preference for the BW maternal call. Yoked, noncontingent exposure had no such effect. The introduction of variability to the contingency, but not a lengthening of the training session, was found to engender even higher preferences for the JQ call. Chicks provided with contingent exposure to the JQ call on a variable ratio schedule showed a significant preference for the JQ over the BW maternal call, whereas chicks provided with equivalent fixed ratio exposure did not. These results highlight the role that social interaction and contingency can play in the acquisition and maintenance of species-specific auditory preferences in precocial avian species.

Asymmetrical hatching behaviors: the development of postnatal motor laterality in three precocial bird species.

The effects of asymmetrical hatching behaviors on the development of turning bias and footedness in domestic chicks, bobwhite quail, and Japanese quail chicks were examined. Control tests with incubator reared domestic chicks and bobwhite quail revealed significant individual and population left-side turning bias and right footedness. When late stage hatching behaviors were disrupted, population laterality was not evident and individual laterality was reduced. By contrast, Japanese quail chicks demonstrated no population turning bias or footedness and only weak individual biases. Disruption of hatch behaviors further decreased laterality. Examination of discarded eggshells showed significant differences in the degree of rotation made to cut out of the egg by Japanese quail versus domestic chicks and bobwhite quail. Taken together these findings suggest that the counterclockwise hatching behaviors that are characteristic of many precocial bird species serve to facilitate the development of motor laterality at both the individual and population level.

Effects of 2 G hypergravity exposure on Bobwhite (Colinus virginianus) and Japanese quail (Coturnix coturnix japonica).

We compared reproductive fitness and early postnatal growth of Bobwhite (Colinus virginianus) and Japanese (Coturnix coturnix japonica) quail incubated and hatched during 2 G centrifugation. Fertilized Bobwhite and Japanese quail eggs were placed in portable incubators on the 8-ft International Space Station Test Bed (ISSTB) Centrifuge at NASA Ames Research Center. The quail eggs were incubated throughout hatching and reared until Postnatal day (P)4 at either 1.0, 1.2 or 2.0 G. Two days before hatching, candling revealed significantly greater numbers of viable Bobwhite than Japanese quail eggs at all g-loads. Bobwhite quail exhibited significantly better hatching success at all g-loads than did Japanese quail. Bobwhite hatchlings were sensitive to gravitational loading as evidenced by reduced postnatal body mass and length of 2 G hatchlings relative to 1 G control hatchlings. In contrast, mass and length of Japanese quail hatchlings were unaffected by 1.2 or 2 G exposure. Together, our findings provide evidence for superior viability and hatching success in Bobwhite quail relative to Japanese quail, coupled with greater sensitivity of postnatal body growth and development to 2 G loading. Bobwhite quail may be better suited than Japanese quail for scientific studies on space biology platforms.

Dietary oral exposure to l,3,5-trinitro-1,3,5-triazine in the northern bobwhite (Colinus virginianus).

The potential risk to wildlife from exposure to explosives, including 1,3,5-trinitro-1,3,5-triazine (RDX), has been an issue at numerous U.S. military installations where these substances are found in soil and water. Presently, no data describing the effects of RDX exposure in avian species exist. Therefore, an acute lethal dose (ALD) and 14- and 90-d subchronic dietary exposures to RDX were evaluated in a species potentially present at many contaminated sites, i.e., the northern bobwhite (Colinus virginianus). The ALDs for females and males were 187 and 280 mg/kg, respectively. Data from the 14-d dietary trial suggested that RDX exposure inhibited food consumption, weight gain, and egg production. Dietary RDX exposure for 90-d produced a dose-dependant decreasing trend in total feed consumption, total egg production, and hen-housed production parameters. These collective data suggest that quail may respond differently to oral RDX exposure compared with mammals.

Intersensory experience and early perceptual development: postnatal experience with multimodal maternal cues affects intersensory responsiveness in bobwhite quail chicks.

Unlike the other sensory modalities of precocial infants, the visual modality does not normally become functional until after birth or hatching. Despite this unique developmental status, the role of emerging visual experience on postnatal perceptual organization remains unclear. In this study, bobwhite quail hatchlings were reared in conditions that manipulated postnatal experience with maternal visual cues, either alone or in conjunction with maternal auditory cues. Results revealed that bobwhite chicks require postnatal exposure to both maternal auditory and visual cues following hatching to demonstrate species-specific perceptual preferences. Chicks that received temporally disparate maternal auditory and visual cues or experience with only maternal visual or maternal auditory cues failed to show species-typical perceptual responsiveness. These results suggest that developmental mechanisms involving both visual and auditory sensory experience underlie the emergence of early intersensory integration.

Prenatal visual experience influences the development of turning bias in bobwhite quail chicks (Colinus virginianus).

This study examined the effects of prenatal sensory experience on the development of turning bias in a precocial avian species (bobwhite quail). Control tests with naive bobwhite quail chicks revealed a left-side turning bias in 85% of subjects. Such large population biases are considered unusual in nonhuman species. Experiments 1, 2, and 3 demonstrated that prenatal visual experience is a significant contributor to this population level left-side turning bias in bobwhite quail chicks. In contrast, prenatal auditory experience did not appear to significantly influence the development of postnatal turning bias. The findings of this study are discussed in terms of an epigenetic theory for the development of hemispheric specialization and behavioral asymmetry.

Growth rate and maturation of skeletal muscles over a size range of galliform birds.

The relationship between growth rate and development of function in leg and pectoral muscles was studied in four species of galliform birds ranging from 125 g to 18 kg and, for comparison, in an altricial species, the European starling (80 g). An index to neonatal maturity (muscle dry content proportion as a fraction of adult value) was higher in leg than in pectoral muscles and lower in larger than in smaller galliforms. The maturity index was substantially lower in starling neonates. After the first week posthatch, however, the maturity index was highest in larger species. Exponential growth rates decreased linearly with increasing maturity in both pectoral and leg muscles, following similar regressions in all species including the starling. At a particular value of the maturity index, the exponential growth rate was higher in pectoral than in leg muscles. The exponential growth rates of muscles of neonatal large galliforms were lower than expected from their low maturity. This may represent the down-regulation shortly after hatching of the high exponential growth rate needed to reach a large hatching mass in a short incubation period. A slower growth rate immediately posthatch may be necessary if the relatively immature neonatal digestive system cannot deliver nutrients or metabolized energy required for more rapid growth. Smaller species may not be faced with the constraint of rapid growth toward the end of the embryonic period.

Effects of water restriction during growth and adulthood on renal function of bobwhite quail, Colinus virginianus.

Renal function and osmoregulation were studied in bobwhite quail (Colinus virginianus) raised with unrestricted water (chronically unrestricted group) or restricted water (chronically restricted group). There was no difference in urine concentrating ability between adult and juvenile (3.5 or 7.5 week-old) quail. A filtration marker (polyethylene glycol) was infused into adult quail via osmotic minipumps and responses to the following regimens studied: ad libitum water intake, short-term (4-day) water restriction, and acute (1-day) dehydration (withdrawal of all drinking water). Chronically restricted quail had higher urine-to-plasma ratios of polyethylene glycol and lower urine flow rates during short-term restriction. A greater proportion of the reduction in urine flow rate during dehydration was attributable to enhanced tubular reabsorption, rather than reduced rates of filtration, in chronically restricted than in chronically unrestricted birds. Chronically restricted birds also had higher maximum urine-to-plasma ratios of polyethylene glycol (but not higher urine osmolality). These differences occurred in the face of arginine vasotocin concentrations that were not different in the two groups of birds (approximately 15 pg.ml-1 during hydration, and 45 pg.ml-1 during water restriction or dehydration). These observations suggest that chronically restricted quail have an enhanced responsiveness of tubular reabsorption to dehydration, a finding consistent with previous observations of tubule hypertrophy and hyperplasia in these birds (Goldstein and Ellis 1991). Despite this, no difference was found in medullary cAMP levels, either basal or arginine vasotocin- or forskolin-stimulated, in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Research note: Feeding various levels of ground Sesbania macrocarpa Muhl. seed to bobwhite quail.

Two 28-day experiments were conducted to determine the effects of various levels of ground Sesbania macrocarpa Muhl. seed on mature bobwhite quail. In Experiment 1, S. macrocarpa Muhl. seed levels of 0, 1, 2, 3, 4, and 5% were added to a basal diet at the expense of filler and fed to five replicate groups of six 58-wk-old paired quail (one male and one female). Average daily feed consumption, hen-day egg production, average BW change, mortality, fertility, and hatchability were monitored. Four groups of eight individually caged females, 63 wk of age, were each given a diet containing 0, 2, 4, 6, 8 or 10% ground S. macrocarpa Muhl. seed in Experiment 2. A seventh treatment was added that consisted of 10% ground S. macrocarpa Muhl. from an older seed shipment used previously in work with White Leghorn hens. Increasing S. macrocarpa Muhl. seed levels in Experiment 1 did not cause significant deviations from the control treatment for average daily feed consumption, BW change, hen-day egg production, fertility, total hatchability, or hatchability of fertile eggs. In Experiment 2 neither average daily feed consumption nor hen-day egg production were affected by seed level or source. Quail given the 10% seed level using the older seed shipment had a significantly greater weight loss than the control birds. With the exception of this greater weight loss and in contrast with work involving chickens, dietary levels of ground S. macrocarpa Muhl. seed of up to 10% were acceptable to bobwhite quail.