The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
John J. Johnston - One of the best experts on this subject based on the ideXlab platform.
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Development of Nicarbazin as a Reproductive Inhibitor for Resident Canada Geese
2005Co-Authors: Kimberly S. Bynum, John J. Johnston, Christi A. Yoder, John D. Eisemann, Lowell A. MillerAbstract:Expanding populations of resident Canada geese that remain in suburban and urban areas year-round often result in increased conflicts with humans. Non-lethal and humane means are needed for managing the size of Canada goose flocks residing near or on airports, golf courses, industrial parks, government sites, and city parks. A side effect of Nicarbazin, a veterinary drug used to control coccidiosis in chickens, is decreased egg production and hatching. Exploiting this side effect, studies of Nicarbazin for reducing the hatchability of eggs from Canada geese were conducted. An initial study in Coturnix quail verified reduction in hatchability in a species other than chickens. Because plasma Nicarbazin was not routinely measured, a study in chickens was conducted to determine the relationship between plasma and egg Nicarbazin. A comparative study in chickens, mallards, and Canada geese showed that Nicarbazin absorption was lowest in geese. Studies in both penned and wild Canada geese showed that reduction in hatchability was possible but neither study used bait suitable for general field application. Bait development led to the OvoControl-G® (Innolytics LLC) bait, which resulted in reduction in hatchability of 51% at treated sites compared to control sites in the field. Previous studies showed that Nicarbazin is practically non-toxic and is environmentally friendly; timing and management of baiting will minimize non-target hazards. OvoControl-G® 2500 ppm Nicarbazin bait is recommended for incorporation into a comprehensive management plan as a reproductive inhibitor for use in controlling resident Canada goose flock sizes.
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determination of 4 4 dinitrocarbanilide dnc a component of Nicarbazin in canada goose branta canadensis eggshells using high performance liquid chromatography
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Randal S. Stahl, Kurt C. Vercauteren, Teresa L Buettgenbach, John J. JohnstonAbstract:A method was developed using high-performance liquid chromatography to assay 4,4′-dinitrocarbanilide (DNC), the active ingredient in Nicarbazin, in eggshells collected from Canada geese fed a formulated feed fortified with Nicarbazin at doses of 0, 125, 250, and 500 Ig/g. The method was developed using chicken eggshells fortified with DNC. The method was used to quantify DNC in both the shell-associated membranes and the calcified shell extracellular matrix. These values were compared to those obtained for a composite sample consisting of both the membranes and the calcified shell extracellular matrix. The validated method was used to quantify DNC in eggshells from geese fed fortified feed to ascertain the effect of Nicarbazin feed concentration on shell DNC concentration. DNC levels in the eggshells were highly correlated with feed dose.
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4,4′‐Dinitrocarbanilide (DNC) concentrations in egg shells as a predictor of Nicarbazin consumption and DNC dose in goose eggs
Pest management science, 2003Co-Authors: Randal S. Stahl, Kurt C. Vercauteren, Dennis J. Kohler, John J. JohnstonAbstract:Nicarbazin is being investigated as an infertility agent for the control of non-migratory Canada geese (Branta canadensis L) populations. Nicarbazin is presently registered for use as a coccidiostat for poultry. Geese fed sufficient quantities of Nicarbazin will lay non-viable eggs. We established Nicarbazin consumption by measuring the concentration of a component of the formulation, 4,4'-dinitrocarbanilide (DNC) in the egg contents (yolk, albumin) in non-viable eggs. To estimate the Nicarbazin consumption of birds that laid viable eggs (eggs that hatched or contained an embryo), a high-performance liquid chromatography method was developed to measure the concentration of DNC in egg shells. A statistically significant correlation was established using linear regression between the mean concentrations of DNC in the egg shell and in the egg contents in non-viable eggs. Viable eggs were estimated to contain lower levels of DNC than non-viable eggs. DNC concentrations in both the egg contents and the egg shell increased with increases in Nicarbazin dose in feed. Our method allows for the estimation of Nicarbazin consumption and DNC dose in eggs under field conditions, which is important in developing an effective infertility agent for over-abundant non-migratory goose populations.
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Quantification of plasma and egg 4,4'-dinitrocarbanilide (DNC) residues for the efficient development of a Nicarbazin-based contraceptive for pest waterfowl.
Pest management science, 2002Co-Authors: John J. Johnston, Christi A. Yoder, Lowell A. Miller, W. M. Britton, Alexander Macdonald, Thomas M. Primus, Margaret J Goodal, Kathleen A. FagerstoneAbstract:Urbanization and associated landscaping has increased the abundance of year-round habitat for waterfowl, resulting in vegetation damage, loss of recreational activities, air transportation mishaps and health hazards. As part of a research program to develop socially acceptable techniques for management of pest bird populations, we are evaluating Nicarbazin as a contraceptive in pest and surrogate avian species. As reproductive studies with Canada Geese (Branta canadensis) are tedious due to the difficulty of conducting controlled field studies and/or breeding geese in captivity, we evaluated the effects of oral Nicarbazin administration on the production and hatchability of chicken eggs. Blood plasma and egg DNC concentrations were correlated to contraceptive efficacy. Subsequent studies are being conducted with geese to determine the diet Nicarbazin concentration required to produce the desired blood and plasma DNC concentrations. This approach permits the expeditious evaluation of formulations and dosing regimes by simply monitoring blood DNC concentrations in target species.
Juliet Roberts - One of the best experts on this subject based on the ideXlab platform.
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Downregulation of ALAS1 by Nicarbazin treatment underlies the reduced synthesis of protoporphyrin IX in shell gland of laying hens
Scientific reports, 2017Co-Authors: S. Samiullah, Juliet RobertsAbstract:Shell colour is an important trait for eggs and an understanding of pigment deposition will assist potential management of egg shell colour loss. We demonstrated that Nicarbazin feeding down-regulated ALAS1 and reduced protoporphyrin IX (PP IX) in both shell gland and eggshell, indicating the role of Nicarbazin in inhibiting the synthesis of PP IX. Additionally, the expression levels of the genes did not show sequential upregulation in the same order of diurnal time-points (TP) during egg formation. The gene SLC25A38, responsible for transporting glycine from cytoplasm to mitochondria, and the gene ALAS1, encoding rate-limiting enzyme (delta-aminolevulinic acid synthase 1), had higher expression at 15 hr, as compared with 2, 5 and 23.5 hrs postoviposition. Interestingly, ABCB6, a gene encoding an enzyme responsible for transporting coproporphyrinogen III, showed higher expression level at 2 and 5 hrs. However, the expression of CPOX that converts coproporphyrinogen III to protoporphyrinogen III, and ABCG2 that transports PP IX out from mitochondria did not alter. Nevertheless, mitochondrial count per cell did not show consistent change in response to time-points postoviposition and Nicarbazin feeding. The information obtained in the study sheds light on how Nicarbazin disrupts the synthesis of PP IX.
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Effect of time-points and combination of time-points and Nicarbazin treatment on the expression stability of reference genes in the shell gland of laying hens.
2017Co-Authors: Sami Samiullah, Juliet RobertsAbstract:A). Mean Cq values of 10 reference genes affected by time-points (Experiment 1). Bars represent standard deviation. B). Pairwise variation (geNorm V) of the optimal number of reference genes affected by time-points (Experiment 1). Pairwise variation (Vn/n+1) was analysed between the normalization factors NFn and NFn+1 to determine the optimal number of reference genes. In the geNorm V graph, each bar represents change in normalization accuracy by stepwise inclusion of most to least stable gene. C). Average expression stability (geNorm M) values of reference genes excluding time-point 2 (post-oviposition time, 2 hours; Experiment 1). Most stable genes have lower M value. Time-point 2 was excluded to compare it with the control group of the time-points and Nicarbazin treatment experiment (Experiment 2). D). Mean Cq values of 10 reference genes affected by time-points and Nicarbazin treatment (control and Nicarbazin groups combined). Bars represent standard deviation. E). Pairwise variation (geNorm V) of the optimal number of reference genes (control, Nicarbazin treated and both the groups combined). F). Average expression stability (geNorm M) values of reference genes (time-points (Experiment 1) and control hens from the time-points and Nicarbazin treated groups (Experiment 2)). Most stable genes have lower M value.
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Overall stability values of reference genes affected by time-points and Nicarbazin treatment.
2017Co-Authors: Sami Samiullah, Juliet RobertsAbstract:Means of relative expression levels in respective groups at three different time-points (post-oviposition times 5, 15, 23.5 hrs) and with Nicarbazin treatments (yes, no) were used to calculate the expression stability of genes in responses to the time points and Nicarbazin treatment across the three statistical software.
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Comparison of the relative expression stability of 10 candidate reference genes analysed by geNorm, NormFinder and BestKeeper.
2017Co-Authors: Sami Samiullah, Juliet RobertsAbstract:The geNorm M and SD values of 10 reference genes were graphed to assess the ranking pattern of the genes assigned by three different software. A). Four different time-points (2, 5, 15, 23.5 hr) post-oviposition in the birds at age of 36–37 weeks. B). Groups treated with or without Nicarbazin at three different time-points (5, 15, 23.5 hr) post-oviposition of birds at 42–45 weeks. C). Three different time-points (5, 15, 23.5 hr) post-oviposition times of the birds without Nicarbazin treatment at age of 42–45 weeks. D). Three different time-points (5, 15, 23.5 hr) post-oviposition of the birds with Nicarbazin treatment at age of 42–45 weeks.
Lowell A. Miller - One of the best experts on this subject based on the ideXlab platform.
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Nicarbazin OvoControl G Bait Reduces Hatchability of Eggs Laid by Resident Canada Geese in Oregon
Journal of Wildlife Management, 2007Co-Authors: Kimberly S. Bynum, Christi A. Yoder, John D. Eisemann, Kathleen A. Fagerstone, Gary C. Weaver, Lowell A. MillerAbstract:Abstract Expanding populations of resident Canada geese (Branta canadensis) are resulting in increased conflicts with humans. Nonlethal and humane means are needed for managing Canada goose flocks at a variety of sites, including golf courses, industrial parks, government sites, and city parks. Decreased egg production and hatching are side effects of Nicarbazin, a veterinary drug used to treat coccidiosis in chickens. Capitalizing on these effects, we developed Nicarbazin as a reproductive inhibitor for Canada geese and conducted a field efficacy study. We recruited study sites in 2002 and 2003. Following laboratory testing, we conducted a field efficacy trial of Nicarbazin for reducing the hatchability of Canada goose eggs in spring 2004 in Oregon, USA. The study began in February 2004 at 10 sites in Oregon, with 2 control and 3 treated sites on each side of the Cascades. We fed bait daily to resident Canada geese for approximately 6 weeks. We located and monitored nests until hatching or ≥5 days beyond...
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Molecular effects of Nicarbazin on avian reproduction
Poultry science, 2006Co-Authors: C. A. Yoder, James K. Graham, Lowell A. MillerAbstract:Nicarbazin (NCZ) is an anticoccidial drug routinely used in the poultry industry that can negatively affect reproduction by reducing egg production, egg weight, and egg hatchability. The molecular mechanisms by which NCZ affects reproduction are unknown. Lipoprotein lipase, vitellogenin, transglutaminase, and calcium are all involved in egg formation and embryogenesis. Therefore, in vitro assays were used to evaluate 4 potential mechanisms of action of NCZ on egg formation and embryogenesis. First, a lipoprotein lipase assay was conducted to determine if NCZ increases lipoprotein lipase activity. Second, vitellogenin phosphorylation was evaluated to determine if NCZ acts as a vitellogenin phosphatase. Third, transglutaminase activity was measured to determine if NCZ inhibits transglutaminase activity. Finally, bull sperm was used as a model to determine if specific channel-mediated calcium uptake can be blocked by NCZ. Nicarbazin increased the activity of lipoprotein lipase in vitro at 3.9 and 7.8 microg of NCZ/mL. Nicarbazin increased intracellular calcium levels in bull sperm, suggesting it also acts as a calcium ionophore. The portion of the NCZ molecule responsible for the increase in intracellular calcium is 2-hydroxy-4,6-dimethylpyrimidine. Nicarbazin affected vitellogenin phosphorylation but only at a concentration many times higher than expected plasma values. Nicarbazin also inhibited transglutaminase activity in vitro. Whereas the 4,4'-dinitrocarbanilide portion of the NCZ molecule inhibited transglutaminase activity, the 2-hydroxy-4,6-dimethylpyrimidine portion increased transglutaminase activity. All of these assays were conducted in vitro; therefore these results should be viewed as preliminary findings to aid in directing further research on the effect of NCZ on reproduction in vivo. Because NCZ increases lipoprotein lipase activity and acts as a calcium ionophore, future experiments should investigate these effects in particular.
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Development of Nicarbazin as a Reproductive Inhibitor for Resident Canada Geese
2005Co-Authors: Kimberly S. Bynum, John J. Johnston, Christi A. Yoder, John D. Eisemann, Lowell A. MillerAbstract:Expanding populations of resident Canada geese that remain in suburban and urban areas year-round often result in increased conflicts with humans. Non-lethal and humane means are needed for managing the size of Canada goose flocks residing near or on airports, golf courses, industrial parks, government sites, and city parks. A side effect of Nicarbazin, a veterinary drug used to control coccidiosis in chickens, is decreased egg production and hatching. Exploiting this side effect, studies of Nicarbazin for reducing the hatchability of eggs from Canada geese were conducted. An initial study in Coturnix quail verified reduction in hatchability in a species other than chickens. Because plasma Nicarbazin was not routinely measured, a study in chickens was conducted to determine the relationship between plasma and egg Nicarbazin. A comparative study in chickens, mallards, and Canada geese showed that Nicarbazin absorption was lowest in geese. Studies in both penned and wild Canada geese showed that reduction in hatchability was possible but neither study used bait suitable for general field application. Bait development led to the OvoControl-G® (Innolytics LLC) bait, which resulted in reduction in hatchability of 51% at treated sites compared to control sites in the field. Previous studies showed that Nicarbazin is practically non-toxic and is environmentally friendly; timing and management of baiting will minimize non-target hazards. OvoControl-G® 2500 ppm Nicarbazin bait is recommended for incorporation into a comprehensive management plan as a reproductive inhibitor for use in controlling resident Canada goose flock sizes.
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Quantification of plasma and egg 4,4'-dinitrocarbanilide (DNC) residues for the efficient development of a Nicarbazin-based contraceptive for pest waterfowl.
Pest management science, 2002Co-Authors: John J. Johnston, Christi A. Yoder, Lowell A. Miller, W. M. Britton, Alexander Macdonald, Thomas M. Primus, Margaret J Goodal, Kathleen A. FagerstoneAbstract:Urbanization and associated landscaping has increased the abundance of year-round habitat for waterfowl, resulting in vegetation damage, loss of recreational activities, air transportation mishaps and health hazards. As part of a research program to develop socially acceptable techniques for management of pest bird populations, we are evaluating Nicarbazin as a contraceptive in pest and surrogate avian species. As reproductive studies with Canada Geese (Branta canadensis) are tedious due to the difficulty of conducting controlled field studies and/or breeding geese in captivity, we evaluated the effects of oral Nicarbazin administration on the production and hatchability of chicken eggs. Blood plasma and egg DNC concentrations were correlated to contraceptive efficacy. Subsequent studies are being conducted with geese to determine the diet Nicarbazin concentration required to produce the desired blood and plasma DNC concentrations. This approach permits the expeditious evaluation of formulations and dosing regimes by simply monitoring blood DNC concentrations in target species.
Christopher T. Elliott - One of the best experts on this subject based on the ideXlab platform.
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investigation of the causes for the occurrence of residues of the anticoccidial feed additive Nicarbazin in commercial poultry
Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2007Co-Authors: Michael Okeeffe, Martin Danaher, Katrina Campbell, Emiliana Capurro, Christopher T. ElliottAbstract:Investigations were undertaken to identify causes for the occurrence of high levels of the zootechnical feed additive Nicarbazin in broiler liver at slaughter. The first investigation on 32 commercial broiler flocks involved sampling and analysis for Nicarbazin (as dinitrocarbanilide, DNC) in liver from birds during a 3–10-day period after withdrawal of Nicarbazin from their feed and before commercial slaughter. DNC residues in liver samples of broilers scheduled as being withdrawn from Nicarbazin for ≥6 days ranged from 20 to >1600 µg kg−1 (the specified withdrawal period for Nicarbazin is 5 days and the Joint Expert Committee on Food Additives (JECFA) maximum residue limit (MRL) is 200 µg kg−1 liver). Further on-farm investigations on 12 of these flocks, selected on the basis of the feeding system in use and the levels of DNC residues determined in liver, identified issues in feed management contributing to elevated residues in broiler liver. A significant correlation (0.81, p < 0.01, n = 10) between DN...
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Development and validation of a lateral flow device for the detection of Nicarbazin contamination in poultry feeds.
Journal of agricultural and food chemistry, 2007Co-Authors: Katrina Campbell, Terence L Fodey, Jonathan Richard Flint, Christopher Danks, Martin Danaher, Michael O'keeffe, D. Glenn Kennedy, Christopher T. ElliottAbstract:Concentrations of the coccidiostat Nicarbazin as low as 2 mg/kg in feed can result in violative drug residues arising in poultry liver. A lateral flow device (LFD) was developed for the detection of contaminating concentrations of Nicarbazin following solvent extraction of poultry feeds. Test results, as determined by both visual and instrumental measurement, are available within minutes. For 22 feed samples, Nicarbazin-free and fortified at 2 mg/kg, the % relative inhibition ranged from 0 to 45% and from 53 to 85%, respectively. Nicarbazin contamination at the critical concentration (2 mg/kg) can be determined in all cases providing the sampling is representative. A wide range of feed samples taken at a mill that incorporated Nicarbazin into poultry feed were analyzed. Data generated for these samples by both the LFDs and a mass spectrometric method were compared, and a significant correlation was achieved.
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Investigation of the causes for the occurrence of residues of the anticoccidial feed additive Nicarbazin in commercial poultry.
Food additives and contaminants, 2007Co-Authors: Michael O'keeffe, Martin Danaher, Katrina Campbell, Emiliana Capurro, Christopher T. ElliottAbstract:Investigations were undertaken to identify causes for the occurrence of high levels of the zootechnical feed additive Nicarbazin in broiler liver at slaughter. The first investigation on 32 commercial broiler flocks involved sampling and analysis for Nicarbazin (as dinitrocarbanilide, DNC) in liver from birds during a 3–10-day period after withdrawal of Nicarbazin from their feed and before commercial slaughter. DNC residues in liver samples of broilers scheduled as being withdrawn from Nicarbazin for ≥6 days ranged from 20 to >1600 µg kg−1 (the specified withdrawal period for Nicarbazin is 5 days and the Joint Expert Committee on Food Additives (JECFA) maximum residue limit (MRL) is 200 µg kg−1 liver). Further on-farm investigations on 12 of these flocks, selected on the basis of the feeding system in use and the levels of DNC residues determined in liver, identified issues in feed management contributing to elevated residues in broiler liver. A significant correlation (0.81, p
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screening for the coccidiostats halofuginone and Nicarbazin in egg and chicken muscle development of an elisa
Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005Co-Authors: Anne-catherine Huet, Terence L Fodey, Christopher T. Elliott, Els Daeseleire, Laurent Mortier, Philippe DelahautAbstract:Nicarbazin and halofuginone have been widely used as coccidiostats for the prevention and treatment of coccidiosis in poultry. It has been shown that accidental cross-contamination of feed can lead to residues of these compounds in eggs and/or muscle. This paper describes a direct competitive assay for detecting halofuginone and Nicarbazin, developed as qualitative screening assay. In an optimized competitive ELISA, antibodies showed 50% binding inhibition at approximately 0.08 ng ml � 1 for halofuginone and 2.5 ng ml � 1 for dinitrocarbanilide (marker residue for Nicarbazin). Extraction from the matrix was carried out with acetonitrile followed by a wash with hexane. The assay’s detection capability
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Screening for the coccidiostats halofuginone and Nicarbazin in egg and chicken muscle: development of an ELISA Part A Chemistry, analysis, control, exposure & risk assessment
Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment, 2005Co-Authors: Anne-catherine Huet, Terence L Fodey, Christopher T. Elliott, Els Daeseleire, Laurent Mortier, Philippe DelahautAbstract:Nicarbazin and halofuginonc have been widely used as coccidiostats for the prevention and treatment of coccidiosis in poultry. It has been shown that accidental cross-contamination of feed can lead to residues of these compounds in eggs and/or muscle. This paper describes a direct competitive assay for detecting halofuginone and Nicarbazin, developed as qualitative screening assay. In an optimized competitive ELISA, antibodies showed 50% binding inhibition at approximately 0.08 ng ml(-1) for halofuginone and 2.5 ng ml(-1) for dinitrocarbanilide (marker residue for Nicarbazin). Extraction from the matrix was carried out with acetonitrile followed by a wash with hexane. The assay's detection capability (CCbeta) for halofuginone was
Christi A. Yoder - One of the best experts on this subject based on the ideXlab platform.
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Nicarbazin OvoControl G Bait Reduces Hatchability of Eggs Laid by Resident Canada Geese in Oregon
Journal of Wildlife Management, 2007Co-Authors: Kimberly S. Bynum, Christi A. Yoder, John D. Eisemann, Kathleen A. Fagerstone, Gary C. Weaver, Lowell A. MillerAbstract:Abstract Expanding populations of resident Canada geese (Branta canadensis) are resulting in increased conflicts with humans. Nonlethal and humane means are needed for managing Canada goose flocks at a variety of sites, including golf courses, industrial parks, government sites, and city parks. Decreased egg production and hatching are side effects of Nicarbazin, a veterinary drug used to treat coccidiosis in chickens. Capitalizing on these effects, we developed Nicarbazin as a reproductive inhibitor for Canada geese and conducted a field efficacy study. We recruited study sites in 2002 and 2003. Following laboratory testing, we conducted a field efficacy trial of Nicarbazin for reducing the hatchability of Canada goose eggs in spring 2004 in Oregon, USA. The study began in February 2004 at 10 sites in Oregon, with 2 control and 3 treated sites on each side of the Cascades. We fed bait daily to resident Canada geese for approximately 6 weeks. We located and monitored nests until hatching or ≥5 days beyond...
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Development of Nicarbazin as a Reproductive Inhibitor for Resident Canada Geese
2005Co-Authors: Kimberly S. Bynum, John J. Johnston, Christi A. Yoder, John D. Eisemann, Lowell A. MillerAbstract:Expanding populations of resident Canada geese that remain in suburban and urban areas year-round often result in increased conflicts with humans. Non-lethal and humane means are needed for managing the size of Canada goose flocks residing near or on airports, golf courses, industrial parks, government sites, and city parks. A side effect of Nicarbazin, a veterinary drug used to control coccidiosis in chickens, is decreased egg production and hatching. Exploiting this side effect, studies of Nicarbazin for reducing the hatchability of eggs from Canada geese were conducted. An initial study in Coturnix quail verified reduction in hatchability in a species other than chickens. Because plasma Nicarbazin was not routinely measured, a study in chickens was conducted to determine the relationship between plasma and egg Nicarbazin. A comparative study in chickens, mallards, and Canada geese showed that Nicarbazin absorption was lowest in geese. Studies in both penned and wild Canada geese showed that reduction in hatchability was possible but neither study used bait suitable for general field application. Bait development led to the OvoControl-G® (Innolytics LLC) bait, which resulted in reduction in hatchability of 51% at treated sites compared to control sites in the field. Previous studies showed that Nicarbazin is practically non-toxic and is environmentally friendly; timing and management of baiting will minimize non-target hazards. OvoControl-G® 2500 ppm Nicarbazin bait is recommended for incorporation into a comprehensive management plan as a reproductive inhibitor for use in controlling resident Canada goose flock sizes.
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Quantification of plasma and egg 4,4'-dinitrocarbanilide (DNC) residues for the efficient development of a Nicarbazin-based contraceptive for pest waterfowl.
Pest management science, 2002Co-Authors: John J. Johnston, Christi A. Yoder, Lowell A. Miller, W. M. Britton, Alexander Macdonald, Thomas M. Primus, Margaret J Goodal, Kathleen A. FagerstoneAbstract:Urbanization and associated landscaping has increased the abundance of year-round habitat for waterfowl, resulting in vegetation damage, loss of recreational activities, air transportation mishaps and health hazards. As part of a research program to develop socially acceptable techniques for management of pest bird populations, we are evaluating Nicarbazin as a contraceptive in pest and surrogate avian species. As reproductive studies with Canada Geese (Branta canadensis) are tedious due to the difficulty of conducting controlled field studies and/or breeding geese in captivity, we evaluated the effects of oral Nicarbazin administration on the production and hatchability of chicken eggs. Blood plasma and egg DNC concentrations were correlated to contraceptive efficacy. Subsequent studies are being conducted with geese to determine the diet Nicarbazin concentration required to produce the desired blood and plasma DNC concentrations. This approach permits the expeditious evaluation of formulations and dosing regimes by simply monitoring blood DNC concentrations in target species.
