Resumen de Estudio del transcriptoma de vacas resistentes a la depresión de la grasa láctea

A. Siurana, D. Gallardo Martínez, Sergio Calsamiglia, A. Cánovas

• Feeding linseed to dairy cows results in milk fat depression (MFD), but there is a wide range of sensitivity, i.e. from cows not showing any reduction in milk fat to cows having a strong MFD. The objective of this study was to compare the mRNA expression of transcripts expressed in milk somatic cells in cows resistant or sensitive to MFD. Four cows were selected from a dairy farm after a switch from a control diet to a linseed-rich diet: two cows(R-MFD) were resistant to MFD showing high milk fat content in both control (4.06%) and linseed-rich diet (4.36%) (R-MFD); and two cows (S-MFD) were sensitive to MFD decreasing milk fat content after the change into the linseed diet (3.56 to 2.54 %). Fresh milk samples were collected from each cow the week before and two weeks after the diet change. Transcriptome analysis was performed using RNA-Sequencing technology with a HiSeq2000 platform. Results showed an overexpression in genes and pathways related to fatty acid synthesis and lipid metabolism such as a TR/RXR and PPARĮ/RXRĮ Activation pathways. Also, several genes and transcription factors such as FOXO3, MTOR, PPARA, PPARG and SREBF1 were identified acting as key regulators in R-MFD cows with linseed-rich diet suggesting the possibility to select cows resistant to MFD. Also, the study of the structural variation in the whole transcriptome of S-MFD and R-MFD cows will contribute to the better understanding of molecular mechanisms affecting the MFD in cows.