Análise genética da espessura do couro, do crescimento pós desmama e das resistências ao carrapato e à babesiose em bovinos de corte

• Ano de defesa: 2015
• Autor(a) principal: Maiorano, Amanda Marchi [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Bovino de corte; Nelore (Zebu); Corpo - Peso; Couros; Carrapato; Babesiose em bovino; Reação em cadeia de polimerase; Body weight
• Link de acesso: http://hdl.handle.net/11449/124066; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/08-06-2015/000834429.pdf

Recent studies about mechanisms of resistance to the tick are rare in cattle, justifying the need for further research. The hide of the animals is one of the tick habitats and some hide features can provide favorable conditions for the establishment and development larval. The aim of this study was to estimate genetic parameters for the skin thickness (ST) and post weaning weight gain (PWG550) of Nellore cattle, and to verify the relationship among skin thickness, tick resistance and parasitaemia level by Babesia bovis in heifers, Caracu and Nellore, that it were artificially infested with ticks. The database of the Nellore Qualitas breeding program was used to estimate the heritability of the ST and PWG550 traits and to verify the genetic association among these traits. Genetics parameters were estimated by bayesian analysis with a multivariate model. Another project phase was developed with 20 Nellore heifers and 20 Caracu heifers, belonging to the Instituto de Zootecnia, in order to allow the study the association of the resistance to tick with parasitaemia level by B. bovis and skin thickness. Heifers were submitted to three (3) ticks' artificial infestations, with 14 days interval. ST was measured in the mid-side area of animals with a double caliper. Engorged females counts were performed in the range of 19th and 23th days after infestation. Blood samples were collected on the 1st, 7th, 21th, 35th and 49th day of the experiment. Blood samples were used to evaluate the parasitaemia level by B. bovis, by quantitative PCR (qPCR) method. Statistical analysis were performed using the MIXED procedure of SAS. Estimates heritability (h²) of the ST and PWG550 traits were 0.12 and 0.29, respectively. Correlation coefficient among the EC and GPD550 traits was 0.17. Nellore showed lower amount of ticks in artificial infestations, however, both groups were efficient to control the B. bovis parasitaemia. The skin thickness group effect was ...