Bovine milk is important for human nutrition. Among its components, fat is the main source of energy and influences the taste of milk and dairy products. Nonetheless milk fat has a high concentration of saturated (SFA) and a low concentration of monounsaturated (MUFA) and poly- unsaturated (PUFA) fatty acids beneficial to human health. Fatty acid profile may change if a targeted breeding program could be applied. In this work the Italian Simmental (IS) breed, a dual-purpose cattle type (milk and meat production), was compared to the Italian Holstein (IH) breed, a milk production cow selected for high yielding, with the aim to highlight the genetic differences or similarities in fatty acid (FA) genetic architecture, using a genome-wide association (GWAS) approach. Peripheral blood and milk samples were collected in 6 commercial farms of IS and 4 commercial farms of IH from about 1000 animals for DNA isolation and FA profiling respectively. Animals were sampled in the same physiological state (mid lactation), to minimize differences due to the stage of lactation. Each milk sample was split in two aliquots, one used for the determination of protein, fat, lactose and for somatic cell count (SCC) and the second frozen at -20C within 2hours, for fatty acid analyses by gas chromatography technology. For each breed, a single SNP genome-wide association analysis was carried out, using as fixed effects milk yield, fat and protein percentage content, SCC, parity, days in milk and farm. Thereafter, MUGBAS was used as gene-centred postGWAS method for the identification of candidate genes. Significant candidate genes identified by MUGBAS were further included in a pathways interaction analysis. A number of candidate genes were identified in both breeds. Some, as DGAT1, SCD, FASN known to be involved in fatty acid metabolism and found associated to FA composition in other studies. Others identified here for the first time, e.g.: GHITM on BTA 28 associated with PUFA/SFA and ERLIN1 on BTA 26 associated with DI 14-1/(14þ14-1) respectively in the IS and IH. Although further investigations are required, different candidate genes in the two breeds, were found, which could explain the differences in FA profiles and might also be useful in future breeding programs.

Genome-wide association study of milk fatty acid composition in Italian Simmental and Italian Holstein cows

SGORLON, Sandy;
2017-01-01

Abstract

Bovine milk is important for human nutrition. Among its components, fat is the main source of energy and influences the taste of milk and dairy products. Nonetheless milk fat has a high concentration of saturated (SFA) and a low concentration of monounsaturated (MUFA) and poly- unsaturated (PUFA) fatty acids beneficial to human health. Fatty acid profile may change if a targeted breeding program could be applied. In this work the Italian Simmental (IS) breed, a dual-purpose cattle type (milk and meat production), was compared to the Italian Holstein (IH) breed, a milk production cow selected for high yielding, with the aim to highlight the genetic differences or similarities in fatty acid (FA) genetic architecture, using a genome-wide association (GWAS) approach. Peripheral blood and milk samples were collected in 6 commercial farms of IS and 4 commercial farms of IH from about 1000 animals for DNA isolation and FA profiling respectively. Animals were sampled in the same physiological state (mid lactation), to minimize differences due to the stage of lactation. Each milk sample was split in two aliquots, one used for the determination of protein, fat, lactose and for somatic cell count (SCC) and the second frozen at -20C within 2hours, for fatty acid analyses by gas chromatography technology. For each breed, a single SNP genome-wide association analysis was carried out, using as fixed effects milk yield, fat and protein percentage content, SCC, parity, days in milk and farm. Thereafter, MUGBAS was used as gene-centred postGWAS method for the identification of candidate genes. Significant candidate genes identified by MUGBAS were further included in a pathways interaction analysis. A number of candidate genes were identified in both breeds. Some, as DGAT1, SCD, FASN known to be involved in fatty acid metabolism and found associated to FA composition in other studies. Others identified here for the first time, e.g.: GHITM on BTA 28 associated with PUFA/SFA and ERLIN1 on BTA 26 associated with DI 14-1/(14þ14-1) respectively in the IS and IH. Although further investigations are required, different candidate genes in the two breeds, were found, which could explain the differences in FA profiles and might also be useful in future breeding programs.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1112679
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