Mercury toxicity as compared to adrenocorticotropin-induced physiological stress in the chicken

Jp, Thaxton; J, Gilbert; Py, Hester; Brake, J.

doi:10.1007/bf01056080

Cited by 22 publications

(7 citation statements)

References 24 publications

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“…Several other stress validation signals exist, ranging from increases in blood glucose [27,29] to cholesterol [24,27,28,66,69,71,72]. However, for broiler nutritional research, many of these procedures are impractical owing to the time and labor that must be devoted because much of this research is conducted by examining pens as opposed to examining individual birds.…”

Section: Validation Of Physiological Stress Models For Poultrymentioning

confidence: 96%

Physiological stress in broilers: Ramifications on nutrient digestibility and responses

Virden

Kidd

2009

Journal of Applied Poultry Research

113

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Physiological stress is one of many concerns facing the modern broiler producer. Research has yet to reveal mechanisms that would allow the producer to efficiently minimize the detrimental impacts of physiological stress on broiler performance. One possible approach for improvement in this area is to elucidate the effects of different nutrient regimens on stressed broilers. Sufficient prior knowledge of the effects of stress on metabolism and nutrient digestibility, as well as effective stress induction models, is essential to any researcher interested in delineating the effects of nutrients on stressed broilers. This review examines the physiological mechanisms that activate and control stress, as well as the effects of stress on immunity, metabolism, and broiler performance. Validation procedures for stress induction models are also examined. Additionally, this review examines available research focused on amino acid digestibility in the presence of stress, digestibility assays necessary for this research, and nutrients that have been shown to have the potential for stress reduction or amelioration.

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Section: Validation Of Physiological Stress Models For Poultrymentioning

confidence: 96%

Physiological stress in broilers: Ramifications on nutrient digestibility and responses

Virden

Kidd

2009

Journal of Applied Poultry Research

113

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“…Methylmercury has been sug-gested to contribute to the decline of the common loon (Gavia immer) in the northern United States; however, ecological variables confounded with MeHg exposure limit inference in the contaminated Great Lakes region [10]. Thaxton et al [11] showed a decrease in plasma corticosterone concentration with increasing MeHg in chickens (Gallus domesticus), but Heath and Frederick [8] found no relationship between mercury exposure and plasma corticosterone concentration in breeding white ibises. These studies strongly suggest a link between MeHg exposure and breeding success or breeding population size via the mechanism of endocrine expression.…”

Section: Introductionmentioning

confidence: 99%

Sublethal effects of methylmercury on fecal metabolites of testosterone, estradiol, and corticosterone in captive juvenile white ibises (Eudocimus albus)

Adams¹,

Frederick²,

Larkin³

et al. 2009

Enviro Toxic and Chemistry

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Methylmercury (MeHg) is a globally distributed neurotoxin, endocrine disruptor, and teratogen, and its effects on birds are poorly understood, especially within an environmentally relevant exposure range. In an effort to understand the potential causal relationship between MeHg exposure and endocrine development, we established four dietary exposure groups (0 [control], 0.05, 0.1, and 0.3 mg/kg wet wt/d of MeHg) of postfledging white ibises (Eudocimus albus) in a divided, free-flight aviary that spanned the estimated range of environmental exposure for this species. Fecal samples were collected from individually identified ibises over six months in 2005 and processed for hormone evaluation. Significant sex-related differences in fecal estradiol concentrations, though unpredicted in direction, suggest that this steroid could be related to juvenile development in this species. Using repeated-measures general linear models, we tested a set of candidate models to explain variation in endocrine expression. We found that MeHg exposure led to significant differences in fecal estradiol concentrations between the control and medium-dose groups, whereas differences in fecal corticosterone concentrations were observed between the control and both the low- and high-dose groups. These results suggest highly nonlinear dose-response patterns for MeHg. Many endocrine-disrupting contaminants are theorized to affect multiple endpoints in a nonlinear manner, making results difficult to interpret using a traditional toxicological approach. The evidence presented here suggests that endocrine effects of MeHg exposure could behave similarly.

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“…Evidence indicates both direct and indirect links between methylmercury exposure and learning. Methylmercury has been suggested to alter thyroid hormones in vertebrates [10] and is correlated to changes in corticosterone in chickens ( Gallus domesticus ) [11] and in testosterone, estradiol, and perhaps, progesterone in the white ibis ( Eudocimus albus ) [12]. Steroid hormones like estradiol and testosterone [13,14], thyroid hormone [15,16], and glucocorticoids [16,17] have important roles in brain development and learning.…”

Section: Introductionmentioning

confidence: 99%

Effects of methylmercury and spatial complexity on foraging behavior and foraging efficiency in juvenile white ibises (Eudocimus albus)

Adams

Frederick

2008

Enviro Toxic and Chemistry

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Methylmercury is a globally distributed neurotoxin, endocrine disruptor, and teratogen, the effects of which on wildlife at environmentally relevant levels are largely unknown. In birds, foraging efficiency and learning may be sensitive endpoints for sublethal methylmercury toxicity, and these endpoints also may be biologically relevant at the population level. In the present study, groups of wild-caught, prefledgling white ibises (Eudocimus albus) were raised in a free-flight, open-air aviary on diets that approximated the measured range of methylmercury exposure in the Everglades ecosystem (0, 0.05, 0.1, and 0.3 mg/kg/d). The effect of methylmercury exposure on group foraging efficiency was examined by allowing birds to forage on 200 fathead minnows (Pimephales promelas) in artificial ponds for 15 min by straining the arenas' contents through a seine net and counting all remaining prey. Additionally, we varied the difficulty of foraging by these tactile feeding birds by adding multiple levels of structural complexity (e.g., increased vegetation and prey refugia) to the pond. Structural complexity affected both foraging efficiency and the rate of increase in efficiency over time (improvement). Methylmercury exposure affected foraging efficiency (p = 0.03). It did not affect foraging improvement in the face of increasingly challenging environments, however, and the dose-response relationship was nonlinear (e.g., the control and high-exposure groups were the least efficient foragers). Evidence for an effect of methylmercury on foraging efficiency therefore was inconclusive because of unpredicted results and no interaction with time or habitat complexity. These data suggest a nonlinear dose-response relationship at low levels of methylmercury exposure; future research is needed to verify this hypothesis. This appears to be the first experimental demonstration of the effects of habitat complexity on foraging efficiency in long-legged wading birds.

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Mercury toxicity as compared to adrenocorticotropin-induced physiological stress in the chicken

Cited by 22 publications

References 24 publications

Physiological stress in broilers: Ramifications on nutrient digestibility and responses

Physiological stress in broilers: Ramifications on nutrient digestibility and responses

Sublethal effects of methylmercury on fecal metabolites of testosterone, estradiol, and corticosterone in captive juvenile white ibises (Eudocimus albus)

Effects of methylmercury and spatial complexity on foraging behavior and foraging efficiency in juvenile white ibises (Eudocimus albus)

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