Clostridial dermatitis (CD) is a multifactorial disease of rapidly-growing turkeys. Clostridium septicum (Cs) has been identified as the primary cause, although C. perfringens (Cp) has also been implicated. Pathogenesis is not fully understood; however, it is hypothesized that Clostridia translocate from the gastrointestinal tract and spread hematogenously to capillary beds of skeletal muscles. Intense genetic selection has produced a rapidly growing bird that is heavier and less active. This may predispose birds to development of CD due to positional restriction of blood flow to the caudal breast and medial thigh. Subsequent reduction in oxygen tension within these tissues produces conditions conducive to germination, proliferation, and toxin production by previously trapped, non-replicative Clostridia. Studies were undertaken to investigate the epidemiology and pathophysiology of CD. Retrospective epidemiologic investigations evaluated incidence, risk factors, and economic impact of CD. Cs and Cp qPCR were performed on blood and tissue samples to demonstrate hematogenous spread in asymptomatic birds. Studies assessed the effect of prolonged recumbency by measuring oxygen saturation and surface temperature in dependent tissues. Tissues from CD cases were evaluated for Cs and Cp alpha toxin mRNA (CsA and CpA). Analyses were conducted to determine associations between these toxins and severity of histopathologic lesions. Whole genome sequencing was performed on the Cs type strain to identify other toxin genes. Flock type, breed, weight at time of processing, and stocking density affected disease incidence. Detection of Clostridium spp. in intestine, liver, and muscle from asymptomatic turkeys without cutaneous trauma implies hematogenous spread from an endogenous source. Focal polyphasic myonecrosis in dependent muscles of asymptomatic turkeys suggests an underlying predisposition to development of CD. Recumbency appeared to be associated with decreased perfusion to these tissues. Cs DNA was present in asymptomatic birds without corresponding CsA mRNA expression suggesting that organisms were present in a quiescent form. CsA was associated with CD while CpA did not appear to be involved in pathogenesis. Genome sequencing identified several coding regions which may correspond to other potentially active Cs toxins. These results support the proposed mechanism of pathogenesis and provide targets for further investigation of disease pathophysiology and vaccine development. / Ph. D.

No description available.

no abstract provided by author / Ph. D.

Several experiments were conducted to identify the limiting amino acids in a 22% corn-soybean meal diet for poults from one to three weeks of age. Additional studies were designed to investigate changes in muscle composition and protein turnover in response to essential (EAA) and nonessential amino acid (NEAA) supplementation of the low protein diet. Developmental changes in muscle metabolism as well as differences between muscles were also examined. Protein synthesis was determined using a ¹⁴C-tyrosine emulsion technique. Protein degradation was calculated as the difference between synthesis and deposition rates. A 30% protein diet served as a control in all experiments. Methionine was confirmed as the first limiting amino acid. Individual deletion of EAA from a mixture added to the 22% protein diet indicated deficiencies of lysine, threonine and valine. Although lysine was more deficient than valine, the valine deficit was exacerbated by high dietary leucine and isoleucine levels. A dietary level of 1.25% valine was inadequate to support optimum growth, inferring a higher requirement than current recommendations. The addition of methionine, lysine and threonine and valine to the 22% protein diet supported maximum growth but feed efficiency remained depressed. Improvements in performance associated with NEAA supplementation indicated a crude protein deficiency in the 22% protein diet. The weights of the pectoralis and gastrocnemius muscles varied directly with body weight. Increases in pectoralis weight were primarily the result of expansions in DNA-unit size. Changes in DNA-unit size and number of the gastrocnemius could not be demonstrated despite consistent alterations in muscle mass. A supplement of methionine and lysine significantly decreased pectoral synthesis rate although protein synthesis tended to decline with any combination of added amino acids. The fractional synthesis rate in the gastrocnemius was relatively stable regardless of diet although a decrease was noted with methionine supplementation. Therefore, alterations in the fractional rate of protein deposition in both muscles were primarily attributable to fluctuations in degradation. Protein deposition was markedly reduced with methionine and lysine supplementation. However, the fractional and absolute rates of protein deposition were maximized by the combined addition of methionine, lysine, threonine and valine, concurring with body weight gain results. Thus, while equal rates of deposition were obtained with the 30% protein diet and the EAA-supplemented 22% protein diet, the latter represents a considerable reduction in energy expenditure for protein turnover. / Ph. D.

Call number: LD2668 .T4 1957 F46 / Master of Science

Call number: LD2668 .T4 1960 W37

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains viii, 90 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 59-66).

A turkey prolactin (PRL) cDNA, encoding a 199 amino acid turkey PRL (tPRL), was cloned from a pituitary library. The mature PRL shared about 70% homology with mammalian PRLs and about 30% with fish PRLs. Areas of highest homology to other PRLs were located in the carboxyl terminus of the tPRL. Prolactin mRNA analyses, during the reproductive life of the turkey hen, confirmed that the high pituitary and plasma levels of PRL measured during the incubation phase are due to enhanced transcription of the PRL gene. Furthermore, tPRL mRNA levels were highly correlated with pituitary levels of tPRL. Recombinant tPRL (rctPRL), biologically and immunologically similar to pituitary tPRL, was purified from Escherichia coli cultures hosting an expression vector carrying the tPRL cDNA. Polyclonal antibodies raised against purified rctPRL behaved similar as antibodies raised against pituitary derived tPRL, in immunoblotting and immunocytochemistry experiments. Three tPRL isoforms (with estimated molecular weights of 27 kDa, 25 kDa and 24 kDa) were identified in turkey pituitary extracts. The relative proportion of the 27 kDa isoform increased while that of the 25 kDa decreased with increasing levels of total pituitary tPRL, during the reproductive life of the turkey hen. The partition of the immunoreactivity of tPRL into the three isoforms perhaps provides an additional control of the multitude functions of PRL.

Freie Universiẗat, Diss., 2008--Berlin.

Zugl.: Berlin, Freie Universiẗat, Diss., 2008. / Includes bibliographical references.