title: Genome-wide association of coagulation properties, curd firmness modeling, protein percentage, and acidity in milk from Brown Swiss cows.
abstract: Cheese production is increasing in many countries, and a desire toward genetic selection for milk coagulation properties in dairy cattle breeding exists. However, measurements of individual cheesemaking properties are hampered by high costs and labor, whereas traditional single-point milk coagulation properties (MCP) are sometimes criticized. Nevertheless, new modeling of the entire curd firmness and syneresis process (CFt equation) offers new insight into the cheesemaking process. Moreover, identification of genomic regions regulating milk cheesemaking properties might enhance direct selection of individuals in breeding programs based on cheese ability rather than related milk components. Therefore, the objective of this study was to perform genome-wide association studies to identify genomic regions linked to traditional MCP and new CFt parameters, milk acidity (pH), and milk protein percentage. Milk and DNA samples from 1,043 Italian Brown Swiss cows were used. Milk pH and 3 MCP traits were grouped together to represent the MCP set. Four CFt equation parameters, 2 derived traits, and protein percentage were considered as the second group of traits (CFt set). Animals were genotyped with the Illumina SNP50 BeadChip v.2 (Illumina Inc., San Diego, CA). Multitrait animal models were used to estimate variance components. For genome-wide association studies, the genome-wide association using mixed model and regression-genomic control approach was used. In total, 106 significant marker traits associations and 66 single nucleotide polymorphisms were identified on 12 chromosomes (1, 6, 9, 11, 13, 15, 16, 19, 20, 23, 26, and 28). Sharp peaks were detected at 84 to 88 Mbp on Bos taurus autosome (BTA) 6, with a peak at 87.4 Mbp in the region harboring the casein genes. Evidence of quantitative trait loci at 82.6 and 88.4 Mbp on the same chromosome was found. All chromosomes but BTA6, BTA11, and BTA28 were associated with only one trait. Only BTA6 was in common between MCP and CFt sets. The new CFt traits reinforced the support of MCP signals and provided with additional information on genomic regions that might be involved in regulation of the coagulation process of bovine milk.
authors.affiliation: Department of Agronomy, Food, Natural resources, Animals and Environment (DAFNAE), University of Padova, Viale dell'Università 16, 35020 Legnaro, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Dadousis
authors.affiliation: Istituto di Biologia e Biotecnologia Agraria (IBBA)-Consiglio Nazionale delle Ricerche (CNR), Via Einstein-Loc. Cascina Codazza, 26900 Lodi, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Biffani
authors.affiliation: Department of Agronomy, Food, Natural resources, Animals and Environment (DAFNAE), University of Padova, Viale dell'Università 16, 35020 Legnaro, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cipolat-Gotet
authors.affiliation: Bioinformatics core, Parco Tecnologico Padano, Via Einstein-Loc. Cascina Codazza, 26900 Lodi, Italy.
authors.forename: E L
authors.initials: EL
authors.lastname: Nicolazzi
authors.affiliation: Italian Brown Breeders Association, Loc. Ferlina 204, Bussolengo 37012, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Rossoni
authors.affiliation: Italian Brown Breeders Association, Loc. Ferlina 204, Bussolengo 37012, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Santus
authors.affiliation: Department of Agronomy, Food, Natural resources, Animals and Environment (DAFNAE), University of Padova, Viale dell'Università 16, 35020 Legnaro, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bittante
authors.affiliation: Department of Agronomy, Food, Natural resources, Animals and Environment (DAFNAE), University of Padova, Viale dell'Università 16, 35020 Legnaro, Italy. Electronic address: alessio.cecchinato@unipd.it.
authors.forename: A
authors.initials: A
authors.lastname: Cecchinato
mesh_terms: D000818:Animals; D002364:Caseins; D002417:Cattle; D002611:Cheese; D005260:Female; D055106:Genome-Wide Association Study; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins
chemical_list: D002364:Caseins; D008894:Milk Proteins
keywords: curd firmness; dairy cattle; genome-wide association study; milk coagulation