Effect of Heat Stress on Serum and Tissue Fatty Acid Profile in Pigs

Studies have shown that heat stress (HS) increases adipose tissue accretion in pigs. However, effects of HS on fatty acid composition are still unknown. The objective of this study was to investigate HS effects on tissue fatty acid composition in pigs, and differentiated pig adipocytes under HS. Pigs were divided into three treatments: control (CON) with ad libitum feed intake and maintained at 22 °C ambient temperature; pair-fed (PF) in which pigs that were pair fed to the feed intake of HS pigs and maintained at 22 °C; heat stress (HS) in which pigs ad libitum feed intake but kept at a constant ambient temperature of 29.4 °C. Pigs were in these treatments for 7 days. Fatty acid composition of serum, adipose tissue, liver and muscle were analyzed by gas chromatography (GC). HS pigs had higher serum (P < 0.05) linoleic acid than PF (21.29 vs. 11.34 %). Both linoleic (10.90 vs. 13.47 %) and gadoleic (0.30 vs. 0.47%) acids were decreased (P < 0.05) in LD muscle in HS pigs compared with PF respectively. In vitro, heat stressed adipocytes differentiated under HS (41.5°C) had a higher (P < 0.05) percent total saturated fatty acids (69.16 vs. 59.34 %) and higher (P < 0.05) monounsaturated fatty acids (28.85 vs. 20.53%) compared to cells at 37.0°C (CON). In conclusion, heat stress induces distinct tissue fatty acid profile in pigs and adipocytes and this could be associated with tissue and cellular heat stress adaptation.