Browsing by Author "Gyenai, Kwaku Barima"

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    An Assessment of the Effects of Oxidative Stress and Dietary Antioxidants on Toxin-Induced Dilated Cardiomyopathy in the Turkey (Meleagris gallopavo)
    Gyenai, Kwaku Barima (Virginia Tech, 2009-12-16)
    Dilated cardiomyopathy (DCM) or round heart disease is a muscle disease of the heart characterized by left ventricular dilatation and abnormal systolic and diastolic ventricular function. In animals, including turkeys and humans, DCM is a major cause of morbidity and mortality that results in heart failure. In the turkey, DCM can be idiopathic or induced. Since idiopathic or spontaneous DCM occurs in about 2-4 % of normal turkeys, it is of significant concern to the poultry industry. This dissertation was designed to increase our understanding of the pathophysiology of DCM in commercial turkeys. Specific objectives included: evaluating the influence of dietary selenium (Se) and vitamin E on poults fed toxic levels of furazolidone (Fz). Evaluating differences among reciprocal crosses of turkey varieties in susceptibility to a toxic level of Fz that induces DCM were used to assess the role of genetics in DCM. Using glutathione (GSH), glutathione peroxidase (GPx), malondialdehyde (MDA), and plasma uric acid (PUA) as biomarkers, oxidative stress (OS) levels were evaluated. Oxidative stress was also evaluated in poults fed diets containing varying concentration and combinations of vitamin E (0, 50 and 100 IU/kg) and Se (0.0, 0.3 and 0.5 mg/kg). Results from echocardiography measurements at four weeks of age, for poults fed toxic levels of Fz, showed the Narragansett x Bourbon Red reciprocal cross had the lowest internal-diastolic (LVIDd) and systolic dimensions (LVISd), while the Bourbon Red x Narragansett reciprocal cross had the largest LVIDd and LVISd. Left ventricular internal-diastolic and systolic dimension were lower for cross bred than parental poults. In treatment poults, heterosis for ventricular dilation was most significant for Bourbon Red x Narragansett cross. The data suggest that reciprocal crosses respond differently to toxin that induces DCM and genetics may influence a turkey's response to toxic levels of Fz that causes DCM. Results from OS measurements in poults fed normal and those fed normal diets with Fz at two weeks of age, showed no significant differences in MDA and GPx levels. PUA and GSH levels were however significantly increased for poults fed Fz-containing diets. At four weeks of age, no differences were observed for MDA and GPx measurements between poults fed normal and Fz-containing diets. PUA levels increased for poults fed normal diets with Fz, while GSH levels increased only for those fed normal diets. Differences between poults fed normal and Fz-containing diets were significant for GPx measurements. Results of this study showed that, feeding diets with Fz does not increase OS. Measure of the influence of feeding diets supplemented with different concentrations and combinations of Se and vitamin E to poults fed either normal or normal diets with Fz at two and four wks of age, showed higher MDA levels for poults fed Fz-containing diets supplemented with 0.3 mg/kg Se and 100 IU/kg vitamin E. For antioxidant biomarkers, GPx activity were increased for poults fed normal diets with Fz supplemented with 0.5 mg/kg Se and those fed 100 IU/kg vitamin E. Poults fed normal diets supplemented with 100 IU/kg vitamin E had the highest GPx. PUA levels were higher for poults fed normal diets with Fz supplemented with 0.5 mg/kg Se at two wks of age. At four wks of age, PUA concentrations were higher for poults fed Fz-containing diets supplemented with 100 IU/kg vitamin E. Increased PUA were also observed for poults fed diets supplemented with 0.5 mg/kg Se and 50 IU/kg vitamin E and 0.5 mg/kg and 100 IU/kg vitamin E. Poults fed diets supplemented with 50 and 100 IU/kg vitamin E had the highest GSH at two wks of age. Measurements taken at 2 wks of age, for poults fed normal diets supplemented with different concentrations and combinations of Se and vitamin E had increased GSH levels when compared with those fed diets with Fz at four wks of age. In this study, we showed that supplementation of poults fed normal diets with Fz with different concentrations and combinations of Se and vitamin E did not reduce DCM at 2 wks of age. However, at 4 wks of age, though DCM was not decreased by feeding diets supplemented with different concentrations and combinations of Se and vitamin E, reduced oxidant and antioxidant biomarkers were observed.
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    Genetic Analysis of Toxin-Induced Dilated Cardiomyopathy in the Turkey (Meleagris gallopavo)
    Gyenai, Kwaku Barima (Virginia Tech, 2005-07-22)
    Dilated cardiomyopathy (DCM) or round heart disease is a muscle disease of the heart which is characterized by ventricular dilatation and abnormal systolic and diastolic left ventricular function. In animals, including turkeys and humans, DCM is the major cause of morbidity and mortality which results from heart failure. In the turkey, DCM can be idiopathic or induced. Since idiopathic or spontaneous DCM occurs in about 1-4% of normal turkeys, it is of significant concern to the poultry industry. In this study, it was proposed that the incidence and severity of DCM in the turkey may have a genetic basis. To test this hypothesis, I investigated differences in the incidence and severity of DCM in five domesticated turkey varieties including Blue Slate (BS), Bourbon Red (BR), Narragansett (N), Royal Palm (RP) and Spanish Black (SB). Preliminary investigations tested the reliability of echocardiography (ECHO) as a non-invasive and non-destructive technique for diagnosing DCM in a large number of birds from hatch to four weeks-of-age. One-day-old poults for both the preliminary and hypothesis testing investigations were obtained from Privett Hatcheries (Portales, New Mexico). The birds were raised under standard management conditions. In the preliminary investigation and to test my hypothesis, DCM was induced by feeding birds ad libitum standard diets containing 700 parts per million furazolidone. Results of the preliminary investigations showed that left ventricular end-diastolic dimension (LVEDD) and left ventricular end-systolic dimension (LVESD) were the most consistent ECHO indicators of DCM from hatch to 4 weeks-of-age. Variety differences in response to furazolidone were evaluated using these parameters as well as percent mortality. At 9 days-of-age, differences between control and treatment birds for percent mortality and LVESD were significant in the RP variety only but significant for LVEDD in RP and SB. At 29 and 33 days-of-age, all the pair-wise comparisons between control and treatment birds were significant for both LVEDD and LVESD. On average, the BR variety had the smallest dilatation of the heart and lowest mortality at 33 days-of-age when compared to other varieties. The results described in this thesis show, for the first time, variety differences in the turkey's response to diets containing furazolidone. They provide strong evidence that, like previous reports for idiopathic DCM, an animal's response to Fz-induced DCM has a strong genetic component.