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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

PrediÃÃo do lucro por mudanÃa unitÃria nos critÃrios de seleÃÃo de bovinos leiteiros no semi-Ãrido do Nordeste / Prediction of earnings per unit change in the criteria for selection of dairy cattle in the semi-arid Northeast

Luciano Jany FeijÃo Ximenes 31 August 2009 (has links)
nÃo hà / Os valores econÃmicos representam o lucro por unidade de melhoria nas caracterÃsticas e foram calculados com base em registros zootÃcnicos e contÃbeis de um sistema de produÃÃo de bovinos leiteiros mestiÃos HolandÃs x Guzerà de fazenda comercial situada no semi-Ãrido do SertÃo Central do Estado do CearÃ, Brasil. Para esses cÃlculos foram utilizados dois mÃtodos: 1) a partir da derivada parcial do lucro para cada caracterÃstica (RT - COT) e 2) pela derivada parcial da relaÃÃo RT/COT. Em ambos os mÃtodos os valores econÃmicos foram transformados em equivalente-leite. Para o primeiro mÃtodo, os valores econÃmicos obtidos foram: 0,68/kg para o leite, -9,14/caso de mamite, 29,28 por kg de leite/minuto para fluxo lÃcteo, -41,74/serviÃos-concepÃÃo, 3,67/dia de vida Ãtil, -0,06/dia para idade ao primeiro parto e -9,55/kg de peso corporal. Os valores do segundo mÃtodo foram semelhantes aos do primeiro provavelmente devido a relaÃÃo RT/COT ter sido prÃxima de 1 (1,06). As caracterÃsticas de nÃmero de serviÃo/concepÃÃo, mamite, peso corporal da vaca seca e idade ao primeiro parto apresentaram valores econÃmicos negativos, enquanto que o fluxo lÃcteo, a produÃÃo de leite e a vida Ãtil proporcionaram lucro genÃtico ao sistema. Portanto, todas estas caracterÃsticas devem ser incluÃdas no objetivo econÃmico de seleÃÃo de bovinos leiteiros em fazendas que apresentam manejo e condiÃÃes de criaÃÃo semelhante à avaliada neste estudo. / The economic values represent the profit per unit of improvement in the characteristics were calculated based on husbandry and accountancy records of a production system of dairy cattle crossbred Holstein x commercial farm located in the semiarid of the State of CearÃ, Brazil. For these calculations we used two methods: 1) from the partial derivative of profit for each feature (RT - TOC) and 2) the partial derivative of the ratio RT / COT. In both methods the economic values were converted to equivalent-milk. For the first method, the economic values obtained were 0.68 / kg for milk, -9.14 / case of mastitis, 29.28 per kg of milk per minute for milk flow, -41.74 / services-conception , 3.67 / day of herdlife, -0.06 / day for age at first calving and -9.55 / kg body weight. The values of the second method were similar to the first probably because the ratio RT / COT have been close to 1 (1.06). The characteristics of the number of service / conception, mastitis, body weight, dry cow weight and age at first calving had negative economic values, milk flow, milk yield and herdlife showed genetic profit in the system. Therefore, all these characteristics should be included in the economic objective of selection for dairy cattle on farms that have management and creating conditions similar to that evaluated in this study

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