Percorrer por autor "Kovac, Milena"
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- Estimation of genetic parameters for dairy ewes using random regression animal modelPublication . Cadavez, Vasco; Silva, Amélia; Malovrh, Špela; Kovac, MilenaThe objective of the study was to compare different models in the estimation of genetic parameters for test-day milk records in Churra da Terra Quente (CTQ) ewes. Data comprising 10700 test-day measurements from the first lactation of 3096 ewes were used in analysis of morning milk yield (MMY), afternoon milk yield (AMY), and daily milk yield (DMY). Records before 30 and after 150 days in milk were discharged. Average milk yield was 217.1 g. 198.3 g. and 415.4 g for MMY, AMY, and DMY, respectively. Pedigree le contained 5494 animals. Simple fixed regression animal model (FRM) and random regression animal models (RRM), where ortogonal Legendre polynomials of order 3 were used. The REML method as implemented in the VCE-5 programme was applied for estimation of (co)variance components. Statistical models contained linear regression on days in milk and number of lambs born as fixed effects, while Jock-test-day, permanent environment of a ewe, and direct additive genetic effect were treated as random. Estimates of heritability from FRM were low, from 1.9% fat AMY to 8.2% for AJMY. Heritability estimates from RRM presented a maximum at 60 days of lactation (>- 33.9%) and decreased to values lower than 2.5% at the end of lactation. There is a potential for using random regression to model additive genetic and permanent environmental effects for genetic evaluation in CTQ ewes, especially from the first two thirds of lactation when decision on mating has to be taken.
- Estimation of genetic parameters for dairy ewes using random regression animal modelPublication . Cadavez, Vasco; Silva, Amélia; Malovrh, Špela; Kovac, MilenaThe objective of the study was to compare different models in the estimation of genetic parameters for test-day milk records in Churra da Terra Quente (CTQ) ewes. Data comprising 10700 test-day measurements from the first lactation of 3096 ewes were used in analysis of morning milk yield (MMY), afternoon milk yield (AMY), and daily milk yield (DMY). Records before 30 and after 150 days in milk were discharged. Average milk yield was 217.1 g, 198.3 g, and 415.4 g for MMY, AMY, and DMY, respectively. Pedigree le contained 5494 animals. Simple fixed regression animal model (FRM) and random regression animal models (RRM), where orthogonal Legendre polynomials of order 3 were used. The REML method as implemented in the VCE-5 programme was applied for estimation of (co)variance components. Statistical models contained linear regression on days in milk and number of lambs born as fixed effects, while fock-test-day, permanent environment of a ewe, and direct additive genetic effect were treated as random. Estimates of heritability from FRM were low, from 2.9% for AMY to 8.2% for MMY. Heritability estimates from RRM presented a maximum at 60 days of lactation (≥ 33.9%) and decreased to values lower than 2.5%at the end of lactation. There is a potential for using random regression to model additive genetic and permanent environmental effects for genetic evaluation in CTQ ewes, especially from the first two thirds of lactation when decision on mating has to be taken.
- Modelling lactation curve in dairy sheep rose under extensive production systemPublication . Cadavez, Vasco; Silva, Amélia; Malovrh, Špela; Kovac, MilenaThe objective of this study was to compare the goodness-of- fit of four mathematical functions (Wilmink, 1987; Ali and Schaeffer, 1987; Guo and Swalve, 1995; and a cubic regression model) for modeling lactation curve on dairy ewes. Data comprising 53,428 test-day records of daily milk yield (DMY) of 11,251 ewes raised under extensive production system, collected during six consecutive years (2000 to 2005) by the milking recording program of the Churra da Terra Quente (CTQ) dairy sheep breed, were used. Test-day records registered before 30 and after 150 days in milk (DIM) were discharged. All models presented similar fitting quality, with coefficient of determination between 71.0 and 71.3%, and underestimate the DMY for high production levels; this trend was more pronounced for Wilmink model. All models presented similar data fitting-quality, and Wilmink model presented higher difficulties in modeling the beginning and the end of lactation curve, however, being a model with less parameters can present advantages in dairy ewes productions systems where small number of test days controls per ewe can occur.
- Study of genetic diversity of Bisaro pigs breed by pedigree analysisPublication . Fernandes, S.D.; Malovrh, Špela; Kovac, Milena; Cadavez, VascoThe objective of this work was to study the genetic diversity of the Portuguese autochthonous pig breed Bísaro by pedigree analysis. Data of Bísaro pigs breed was taken from the database of the National Breeders (Association Associação Nacional de Criadores de Suínos de Raça Bísaro - ANCSUB) concerning the period from 1997 to 2008. For both, pedigree and active population files completeness was evaluated. The number and the proportion of animals with both parents known, sire known, and dam known were computed using the SQL procedure. Population genetic diversity parameters were computed, using the PEDIG software package, for the active population which included animals born from 2003 to 2008. The effective number of founders was 78.8 for boars and 79.7 for sows, while the number of ancestors contributed with 50% of the genes in the breed pool gene was 24 for boars and 23 for sows. A high proportion (52.4%) of animals in the active population are inbred, and 43.9% of the inbreed animals presented inbreeding coefficient higher than 20%. These results suggest that genetic variability needs monitoring in order to avoid the losses of genes in the Bísaro pigs.
- Study of genetic diversity of dog cão de gado transmontano breed by pedigree analysisPublication . Rosa, José Luís Nunes; Malovrh, Špela; Kovac, Milena; Cadavez, VascoThe objective of this work was to study the genetic diversity of the Portuguese local dog breed Cao de Gado Transmontano by pedigree analysis. Pedigree data of dog breed Cao de Gado Transmontano was taken from the database of the Associação Criadores de Cao de Gado Transmontano concerning the period from 2003 to 2009. The pedigree file completeness was evaluated. The number and the proportion of animals with both parents known, sire known, and dam known were computed using the SQL procedure. Population genetic diversity parameters were computed using the PEDIG software package. The number of founders was 131 animals; however the effective number of founders was only 58 animals. A low proportion (4.6%) of animals in the population is inbred, and the inbred animals presented low (> 25%) inbreeding coefficient. However, the pedigree completeness is very small, which puts difficulties in the inbreeding calculation. These results suggest that efforts must be made to improve the pedigree quality in order to monitoring the genetic diversity of Cão de Gado Transmontano.