Loading...
Please wait, while we are loading the content...
Similar Documents
Avaliação genética em bubalinos leiteiros utilizando modelo de regressão aleatória
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chaves, Luciara Celi Da Silva |
| Copyright Year | 2009 |
| Abstract | Aiming the evaluation of six measures of milk production persistency, 9.219 test day records of milk production originated from the first lactation of 646 dairy Murrah buffaloes, controlled from 1987 to 2006, were used. The productions at the test day were analyzed by random regression model, considering as fixed effects the contemporary group, number of milking, linear and quadratic effects of the covariable buffalo age at calving, regression coefficient over lactation days, modeled by Legendre orthogonal polynomial of order three, besides the random regression coefficients of the additive genetic and permanent environmental random effects were modeled by the logarithmic function of Ali & Shaeffer. The milk production mean at the test day was 6,63±2,49 kg. The breeding values for milk production of female and male buffaloes along the days in production were growing and negatives at the beginning of the curve until near 30 days of lactation, with highest values within 60 to 90 days. The persistency variable PS1, defined as PS1 = ∑ = − 280 61 60 ) ( t t VGP VGP , where VGPt and VGP60 correspond to the predicted breeding values at the t day and at 60 days in production, respectively, was chosen as a criterion of selection for milk production persistency. It was verified that the selection of individuals with higher breeding values for milk production accumulated until 301 days in production (VGP301ac) favors the selection of animals with higher breeding values for milk production at the beginning of the lactation and less persistent and, in addition, the selection of individuals with higher breeding values for PS1, implies in selection of animals with higher breeding values for milk production at the end of the lactation. simultaneous selection for VGP301ac and PS1 implies in the choice of the most persistent and productive animals. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.locus.ufv.br/bitstream/handle/123456789/1291/texto%20completo.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
