Principal component analysis (PCA) was used to examine the relationship between milk fat content and fatty acid (FA) profile in ewes subjected to different nutritional strategies, with the aim of identifying the most relevant FA potentially involved in diet-induced milk fat depression (MFD). A database comprising lot observations from 15 nutritional trials was built (n=439), but the loading plot derived from PCA showed no apparent relationship between milk fat content and any of the principal components (PC). When the database was split into 2 sub-databases according to experiments showing MFD (i.e., including marine lipid supplementation) or not, PC1 and PC2 described 62.9% of total variation in milk FA and dairy performance in the former. Furthermore, milk fat percentage was negatively correlated with PC2, and loaded near 18:0 and cis-9 18:1 and opposite to a cluster including trans-10 18:1, 20:5n-3 and 22:6n-3. Although these FA do not have to be necessarily involved in MFD in ewes, their concentration in milk could be an indicator of favourable conditions for MFD to occur. Results from all loading plots support that trans-10 cis-12 18:2 does not play a major role in diet-induced changes in milk fat content in dairy ewes.

Este trabajo ha sido financiado por el MINECO (proyecto AGL2011-23700). P. G. Toral y D. Carreño disfrutan, respectivamente, de un contrato Juan de la Cierva y de una beca predoctoral FPI del MINECO.

Trabajo presentado a las XVI Jornadas sobre Producción Animal AIDA (Zaragoza, 19 al 20 de mayo, 2015).

Peer reviewed