The concentrations of fipronil and fipronil metabolites in plasma (Cp) (LOQ = 0.04 ppb) and feces (Cf) (LOQ = 0.1 ppb) were estimated for each individual deer (n = 24). Linear regression (P < 0.05) was used to detect a correlation between Cp or Cf (dependent) and the mg fipronil/kg body weight consumed by white-tailed deer (independent). Linear regression was also used to detect a potential correlation between Cp and survivorship of female I. scapularis and A. americanum ticks.
The concentrations of fipronil and fipronil metabolites within various tissues (Ct) were estimated for 16 FDF-treated deer and two control deer (LOQ = 0.04 ppb). Differences in Ct values among all tissue classifications (fat, meat, meat by-products, liver) were estimated using a Kruskal–Wallis H-test followed by a Wilcoxon signed-rank test within each pair. Differences in Ct values between the T48 and T120 exposure groups estimated for each tissue classification and differences in Ct values of each tissue classification within each test subgroup were estimated using a Wilcoxon signed-rank test. The Ct was compared with the MRL established by the US EPA for ruminant cattle [47 (link)] (meat/muscle = 40 ppb; liver = 100 ppb; meat by-products = 40 ppb; fat = 400 ppb) which are utilized by the US Food and Drug Administration (FDA) when evaluating potential products. The Ct values recorded at each time point post-exposure (day 15, day 29) were used to develop exponential equations to approximate the rate of fipronil degradation for each tissue classification as a function of the number of days post-exposure. The equation was formulated as follows, and is functionally similar to equations previously utilized by Poché et al. [29 (link)] to represent fipronil degradation in bovid plasma and feces: where Ɵ1 = Theta-1 estimate, Ɵ2 = Theta-2 estimate, EXP = exponential, x = days post-exposure.
All analyses were performed using the current versions of JMP statistical software (version 15) (SAS Institute, Cary, NC, USA) and Microsoft Excel. Differences were considered significant if P < 0.05.
The concentrations of fipronil and fipronil metabolites within various tissues (Ct) were estimated for 16 FDF-treated deer and two control deer (LOQ = 0.04 ppb). Differences in Ct values among all tissue classifications (fat, meat, meat by-products, liver) were estimated using a Kruskal–Wallis H-test followed by a Wilcoxon signed-rank test within each pair. Differences in Ct values between the T48 and T120 exposure groups estimated for each tissue classification and differences in Ct values of each tissue classification within each test subgroup were estimated using a Wilcoxon signed-rank test. The Ct was compared with the MRL established by the US EPA for ruminant cattle [47 (link)] (meat/muscle = 40 ppb; liver = 100 ppb; meat by-products = 40 ppb; fat = 400 ppb) which are utilized by the US Food and Drug Administration (FDA) when evaluating potential products. The Ct values recorded at each time point post-exposure (day 15, day 29) were used to develop exponential equations to approximate the rate of fipronil degradation for each tissue classification as a function of the number of days post-exposure. The equation was formulated as follows, and is functionally similar to equations previously utilized by Poché et al. [29 (link)] to represent fipronil degradation in bovid plasma and feces: where Ɵ1 = Theta-1 estimate, Ɵ2 = Theta-2 estimate, EXP = exponential, x = days post-exposure.
All analyses were performed using the current versions of JMP statistical software (version 15) (SAS Institute, Cary, NC, USA) and Microsoft Excel. Differences were considered significant if P < 0.05.
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