Mycoplasmas are responsible for many important diseases of animals, including contagious bovine pleuropneumonia (CBPP) caused by Mycoplasma mycoides subsp. mycoides SC and calf pneumonia, arthritis and mastitis caused by Mycoplasma bovis. However, diagnostic techniques currently available are laborious and imprecise. The work described in this thesis concentrates on the critical evaluation of existing techniques and the development of improved procedures. The role of antimicrobial resistance in limiting the options for disease control was also considered. Diagnostic methods for the detection of M. mycoides subsp. mycoides SC in clinical material were critically evaluated during a CBPP outbreak in Portugal. Immunoblotting was more sensitive and specific than CFT or ELISA. The polymerase chain reaction (PCR) was more rapid and sensitive than culture. However immunocytohistochernistry (ICC) was far the best test for detecting M. mycoides subsp. mycoides SC antigen in lungs. A rapid latex agglutination test (LAT) to detect CBPP using a carbohydrate extract of M. mycoides subsp. mycoides SC was developed. Analysis of the carbohydrate extract composition demonstrated that fucose, glucosamine and galactose are present in the ratio of 1:2:16 respectively. N-acetyl neuraminic acid was also detected. Evaluation of the LAT with sera from negative, naturally infected and experimentally infected cattle demonstrates that the test clearly differentiates positive and negative CBPP sera. The LAT compared favourably with the CFT but was not as specific as the immunoblotting; however the LAT had the advantage of being more rapid and robust and could be used in the field. Molecular methods including the polymerase chain reaction (PCR) and 16S rRNA gene sequencing were assessed for their potential use in the diagnostic laboratory. A PCR method for identifying M. bovis was adapted, evaluated and introduced as a routine laboratory test. Using a set of universal 16S rRNA gene primers, amplicons of two serologically untypable isolates, one from a peregrine falcon, and the other from an ostrich were obtained. Results imply that the isolates may be new mycoplasma species. The development of antimicrobial resistance has been seen in many microorganisms but little evidence exists for resistance in mycoplasmas. Consequently, the in vitro effect of five antimicrobials; danofloxacin, oxytetracycline, spectinomycin, florfenicol and tilmicosin on 62 isolates of M. bovis and 20 of M. mycoides subsp. mycoides SC was investigated. Nfinimum inhibitory concentrations (MICs) and mycoplasmacidal (MMC) values were determined. Evidence of antimicrobial resistance by M. bovis is shown. The potential for M. mycoides subsp. mycoides SC to develop antimicrobial resistance against spectinomycin in vitro is also demonstrated.

No description available.

No description available.

Long-term administration of recombinant bovine somatotropin (rbST) significantly increased milk and 3.5% fat-corrected milk production without altering milk composition. These effects occurred regardless of breed, parity or drug delivery system (daily or sustained-release) utilized. Somatotropin did not affect apparent digestibility of rations, dry matter intake, crude protein intake, energy intake or energy balance. Body energy reserves, measured as body condition scores, decreased during rbST treatment resulting, together with the increase in milk yield, in an improvement of the efficiency of conversion of feed to milk for cows treated with rbST. Body condition was completely regained during the dry period. No effects of rbST on mastitis or metabolic diseases were observed. During lactation, injection of rbST produced elevated circulating concentrations of non-esterified fatty acids, glucose, insulin, bST and IGF-I but lipid composition of liver and ketogenic functions were not altered. These lipolytic and diabetogenic activities might contribute to the galactopoietic response elicited by rbST. Somatotropin did not modify the nutritional status of cows during pregnancy or the nutritional status and growth rate of their calves from birth to weaning. / With regard to reproduction, somatotropin augmented ovarian progesterone production during the first two estrous cycles post-injection and during gestation. These effects may have been mediated through increased ovarian IGF-I synthesis. Somatotropin enhanced the GnRH-induced LH response at 14 d postpartum. In spite of these positive observations, somatotropin treatment tended to produce longer calving to conception intervals. Nevertheless, the higher persistency of milk production by cows treated with rbST may compensate for this difference economically.

Thesis (M.S.)--Ohio University, June, 1995. / Title from PDF t.p.

Thesis (M.S.P.H.)--University of Michigan, 1940.

Thesis (M.S.P.H.)--University of Michigan, 1940.

Thesis--Wisconsin. / Vita. Includes bibliographical references.

Thesis (M.S. in animal sciences)--Washington State University, December 2006. / Includes bibliographical references.

A leucose bovina enzoótica (LBE) é uma enfermidade causada por um retrovírus que possui duas manifestações distintas em animais adultos, o linfossarcoma multicêntrico dos adultos e a linfocitose persistente (LP). O linfossarcoma multicêntrico dos adultos é caracterizado pela apresentação de tumores em diversos órgãos em bovinos com idade superior a dois anos. O presente trabalhou analisou o histórico clínico e os achados patológicos de 30 casos de leucose bovina enzoótica, diagnosticados de um total de 845 bovinos necropsiados no Setor de Patologia Veterinária da Universidade Federal do Rio Grande do Sul, entre o período de janeiro de 1999 a janeiro de 2011. Todos os bovinos afetados eram fêmeas de aptidão leiteira, com idade entre três e nove anos, sendo 27 da raça Holândes (90,0%), dois de raça mista (6,3%) e um Jersey (3,7%). Os principais sinais clínicos apresentados pelos bovinos foram alterações locomotoras caracterizadas por paresia progressiva dos membros, perda de peso, aumento do volume de linfonodos superficiais e exoftalmia. As lesões macroscópicas observadas eram caracterizadas por massas neoplásicas, de coloração branco-amareladas, acinzentadas ou róseas, encontradas nos linfonodos, coração, sobre a meninge da medula espinhal, abomaso, intestinos e rins. A infiltração tumoral sobre a meninge da medula espinhal foi observada em 24 animais, sendo que a região lombar (20/24) e cauda equina (11/24) foram frequentemente afetadas. Ocasionalmente as massas também foram observadas na região cervical (6/24), próximo à intumescência, e na região torácica (2/24). No exame histológico essas massas tumorais eram formadas por infiltrado difuso de linfócitos neoplásicos, sendo apresentada na maioria dos casos como células pequenas não clivadas. A ocorrência de linfossarcoma com infiltração na medula espinhal deve ser considerada no diagnóstico de enfermidades que cursam com alterações locomotoras em bovinos adultos de aptidão leiteira. / The enzootic bovine leukosis (EBL) is a disease caused by a retrovirus that has two distinct manifestations in adult animals, the multicentric lymphosarcoma and persistent lymphocytosis in adults (LP). The multicentric lymphosarcoma in adults is characterized by the presentation of tumors in various organs in cattle older than two years. This study analyzed the clinical history and pathological findings in 30 cases of EBL, diagnosed a total of 845 cattle necropsied in the Setor de Patologia Veterinária of Universidade Federal do Rio Grande do Sul, between the period January 1999 to January 2011. All affected cattle were dairy females, between three and nine years old, and 27 Holstein (90,0%), two cross breed (6,3%) and Jersey (3,7%). The main clinical signs shown by the cattle were changes, locomotor characterized by progressive paralysis of the limbs, weight loss, most prominently superficial lymph nodes and exophthalmus. The gross lesions were characterized by neoplasms masses, pale yellowish-white, grayish or pinkish, found in lymph nodes, heart, on the meninges of the spinal cord, abomasum, intestines and kidneys. The tumor infiltration on the meninges of the spinal cord was observed in 24 animals, and the lumbar (20/24) and cauda equina (11/24) were commonly affected. Occasionally, the masses were also observed in the cervical region (6/24), near the swelling, and in the thoracic region (2/24). In histological examination, these tumor masses were composed of diffuse infiltration of neoplastic lymphocytes, and in most cases presented as small noncleaved cells. The occurrence of lymphosarcoma infiltrating the spinal cord should be considered in the diagnosis of diseases which lead to changes in locomotor adult dairy cattle.