Abstract #T98
Section: Breeding and Genetics
Session: Breeding and Genetics: Applications and methodology in animal breeding - Dairy
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
Session: Breeding and Genetics: Applications and methodology in animal breeding - Dairy
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
# T98
Genetic parameters for production traits and age at first calving in Gyr dairy cattle.
Marco Prata*1,2, Francesca Malchiodi2, Filippo Miglior3,2, Lenira El Faro4, Aníbal Vercesi Filho5, Vera Cardoso1, 1Departament of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil, 2Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, ON, Canada, 3Canadian Dairy Network, Guelph, ON, Canada, 4Centro Avançado de Pesquisa Tecnológica do Agronegócio de Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, SP, Brazil, 5Centro Avançado de Pesquisa Tecnológica do Agronegócio de Bovinos de Leite, Instituto de Zootecnia, Nova Odessa, SP, Brazil.
Key Words: Gyr cattle milk, production, age at first calving
Genetic parameters for production traits and age at first calving in Gyr dairy cattle.
Marco Prata*1,2, Francesca Malchiodi2, Filippo Miglior3,2, Lenira El Faro4, Aníbal Vercesi Filho5, Vera Cardoso1, 1Departament of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil, 2Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, ON, Canada, 3Canadian Dairy Network, Guelph, ON, Canada, 4Centro Avançado de Pesquisa Tecnológica do Agronegócio de Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, SP, Brazil, 5Centro Avançado de Pesquisa Tecnológica do Agronegócio de Bovinos de Leite, Instituto de Zootecnia, Nova Odessa, SP, Brazil.
The selection of Gyr cattle in Brazil has been focused mostly on improving milk yield. However, after the implementation of the Brazilian Agriculture Ministry regulation polices in 2002, which established new parameters for milk quality, producers have shown an interest in increasing fat and protein yield, as well as fat and protein content of milk. Other traits of interest for producers included age at first calving, known to be elevated in Gyr cattle, and which has an important economic impact on dairy farms. The objective of this study was to estimate genetic parameters for 305d milk, fat and protein yield, fat and protein content, and age at first calving for Gyr dairy cattle. The data set consisted of 10,977 records from 8,571 Gyr dairy cows in 245 herds in Brazil. Production traits were analyzed through a linear animal model including the fixed effects of contemporary groups (herd - calving year - calving season - parity) and age at calving as covariable (linear and quadratic effects). Direct additive genetic and permanent environmental effects were included as random effects. The model for age at first calving included the effect of contemporary group (herd - year and season of birth). Estimated heritabilities (SE) for milk, fat and protein yield were 0.23 (0.02), 0.18 (0.04), and 0.13 (0.07), respectively. Fat and protein content showed heritabilities of 0.12 (0.05) and 0.08 (0.07) respectively. Furthermore, the estimated heritability of age at first calving was 0.14 (0.02). The results indicated that the selection for these traits is possible in Brazilian Gyr. However, the low heritability values suggest that environmental factors (i.e., management strategies) could have the highest potential impact on the improvement of these traits. Further analysis should be performed to build a multi-trait selection index for Gyr dairy cattle breeding program in Brazil, to obtain desirable genetic gain for these traits.
Key Words: Gyr cattle milk, production, age at first calving
