Identification of plasma fatty acids as biomarkers for carcass traits and tissue-specific fatty acids profile in pigs

Carcass and pork traits have long been regarded as key phenotypes in pig breeding. The content and composition of fatty acids (FAs) play a crucial role in determining carcass and meat quality in pigs, as their regulation affects fat depositions. The current study integrates the FA composition of blood, liver, backfat and muscle, and explores its relationship with carcass traits in 265 commercial Duroc pigs. In muscle, higher levels of C16:0 and C18:1 n -9 were positively correlated with carcass weight (CW) and fat thickness in backfat (BFT34) and ham (HFT), but negatively correlated with lean percentages. Conversely, PUFA levels in muscle showed the opposite correlation pattern. Backfat FAs like C16:0, C18:0, C20:0, and C20:1 n -9 were positively correlated with CW, BFT34, and HFT, while also negatively correlated with lean meat percentage (LM). Liver FAs such as C16:0, C18:0, and C18:1 n -7 exhibited similar correlation patterns with CW, BFT34, HFT, and LM. Blood FAs showed a different correlation pattern compared to the other tissues, with MUFA and C18:2 n -6 positively correlated with CW, BFT34 and HFT, while the levels of C16:0, C16:1 n -7, C18:1 n -9, and C18:2 n -6 in blood showed a negative correlation with LM. Inter-tissue communication revealed positive correlations between C16:0, C16:1 n -7, C18:1 n -7, and C18:1 n -9. Additionally, the PUFA content in muscle was inversely related to FAs from other tissues. In Duroc pigs, during the early growth stage, there is a positive correlation among the levels of C16:0, C16:1 n -7, C18:1 n -7, and C18:1 n -9 FAs in the blood, which is reflected in their concentrations within the liver, backfat, and muscle tissues after pig slaughter. Moreover, these FAs showed a positive correlation with CW and BFT34 and HFT, and were negatively correlated with LM. Among these FAs, C16:0 and C18:0 as well as the desaturation product C18:1 n -9, along with C18:2 n -6, exhibited great predictive ability in muscle FAs and less ability in carcass traits. In conclusion, the plasma C16:0, C16:1 n -7 C18:0, C18:1 n -9 and C18:2 n -6 are proposed as the main candidate indicators for predicting carcass traits in slaughtered pigs and the FA profile in liver, backfat and muscle.