Abstract
ObjectiveThis study assessed the possible existence of genotype by environment interactions for milk, fat and protein yields in Holstein cattle raised in one of the most important milk production basins in Brazil.MethodsChanges in the genetic parameters and breeding values were evaluated for 57,967 animals from three distinct regions of southern Brazil, divided according to differences in climate. The genotype by environment interaction was determined by genetic correlations between regions, estimated by the restricted maximum likelihood, considering the animal model. Bull rankings were investigated to verify the ratio of coincident selected animals between regions for each trait.ResultsThe estimates of heritability coefficients were similar between two regions, but were lower in the third evaluated area, for all traits. Genetic correlations between regions were high, ranging from 0.91 to 0.99 for milk, fat and protein yields, representing the absence of a genotype by environment interaction for productive traits. The percentage of selection error between regions for the top 10% of animals ranged from 0.88% to 2.07% for milk yield, 0.99% to 2.46% for fat yield and 0.59% to 3.15% for protein yield.ConclusionA slight change in genotype between areas was expected since no significant genotype by environment interactions were identified, facilitating the process of selecting Holstein cattle in southern Brazil.
Highlights
Reproductive biotechnology has resulted in the extensive and global distribution of genetic material from animals with high productive potential
Genotypes that are chosen from areas dissimilar to the region in which they are to be introduced may not satisfy breeder expectations. This aspect may be related to the genotype lacking an adaptation to the territory in which it is introduced; this in turn will affect the genotype by reducing the expression of its maximum productive potential [1]
In Brazil, a major proportion of milk production comes from the Holstein breed [3]
Summary
Reproductive biotechnology has resulted in the extensive and global distribution of genetic material from animals with high productive potential. The present study focused on taining the contemporary group and covariate of the age at assessing the influence of the GEI on the production of milk, birth, a is the vector of the solutions for the additive genetic fat and protein in Holstein herds in Paraná, Brazil.
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