title: Genetic parameters for milk fatty acids, milk yield and quality traits of a Holstein cattle population reared under tropical conditions.
abstract: Information about genetic parameters is essential for selection decisions and genetic evaluation. These estimates are population specific; however, there are few studies with dairy cattle populations reared under tropical and sub-tropical conditions. Thus, the aim was to obtain estimates of heritability and genetic correlations for milk yield and quality traits using pedigree and genomic information from a Holstein population maintained in a tropical environment. Phenotypic records (n = 36 457) of 4203 cows as well as the genotypes for 57 368 single nucleotide polymorphisms from 755 of these cows were used. Covariance components were estimated using the restricted maximum likelihood method under a mixed animal model, considering a pedigree-based relationship matrix or a combined pedigree-genomic matrix. High heritabilities (around 0.30) were estimated for lactose and protein content in milk whereas moderate values (between 0.19 and 0.26) were obtained for percentages of fat, saturated fatty acids and palmitic acid in milk. Genetic correlations ranging from -0.38 to -0.13 were determined between milk yield and composition traits. The smaller estimates compared to other similar studies can be due to poor environmental conditions, which may reduce genetic variability. These results highlight the importance in using genetic parameters estimated in the population under evaluation for selection decisions.
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Petrini
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: L H S
authors.initials: LH
authors.lastname: Iung
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: M A P
authors.initials: MA
authors.lastname: Rodriguez
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Salvian
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: F
authors.initials: F
authors.lastname: Pértille
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: G A
authors.initials: GA
authors.lastname: Rovadoscki
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: L D
authors.initials: LD
authors.lastname: Cassoli
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: L L
authors.initials: LL
authors.lastname: Coutinho
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil.
authors.forename: P F
authors.initials: PF
authors.lastname: Machado
authors.affiliation: Animal Genomics and Improvement Laboratory, Agricultural Research Service, USDA, Beltsville, MD, USA.
authors.forename: G R
authors.initials: GR
authors.lastname: Wiggans
authors.affiliation: Department of Animal Science, University of São Paulo, Piracicaba, Brazil. gbmourao@usp.br.
authors.forename: G B
authors.identifier: http://orcid.org/0000-0002-0990-4108
authors.initials: GB
authors.lastname: Mourão
mesh_terms: D000818:Animals; D002417:Cattle / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D002980:Climate; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D005838:Genotype; D008892:Milk / Q000737:chemistry* / Q000191:economics; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide
chemical_list: D005227:Fatty Acids
keywords: Correlation; dairy cattle; genomics; heritability; single nucleotide polymorphism; somatic cell score