Fatty acid composition of mesenteric, cardiac, abdominal, intermuscular, and subcutaneous adipose tissues from horses of three body condition scores

Body condition score estimates overall adiposity in horses but not fatty acid (FA) composition of fat depots, which is associated with many biological functions and important for horse health. The objectives of the current study were to determine the FA composition of mesenteric (MS), cardiac (CD), abdominal (AB), intermuscular (IM), and subcutaneous (SC) adipose tissues in stock-type horses and identify their relationships with BCS. Twenty-one stock-type horses (BCS 4, n = 7, 468 ± 13 kg; BCS 5, n = 10, 455 ± 11 kg; BCS 6, n = 4,493 ± 12 kg) were humanely euthanized based on 3 primary criteria: geriatric, crippled, and/or unsafe. Fat tissues including MS around the small intestines, CD at the pericardium, AB from abdominal fat located inside the left flank, IM underneath the latissimus dorsi muscle in the thoracic region, and SC on the surface of semitendinosus muscle were collected within 30 min post-mortem, trimmed of connective tissues and muscles, frozen in liquid nitrogen, pulverized into fine powder, and stored at –80 °C. Fatty acids were determined by gas chromatography and expressed in percentage of total FA concentration. Influences of BCS (P 〈 0.05) and fat depot (P < 0.05), but not BCS × fat depot interaction (P > 0.05), were found for most FA, indicating that most FA were independently influenced by BCS and anatomical locations. However, some FA, such as 16:1n7, were influenced by BCS differently in various fat depots (PBCS×fₐₜ dₑₚₒₜ = 0.043). The major FA were palmitic (24.85%), stearic (5.54%), oleic (27.34%), linoleic (11.20%), and linolenic (17.95%) acids. Degree of saturation was not affected by BCS (P = 0.212). Most saturated depots were AB and CD (P ≤ 0.049). In MS, IM, and SC, PUFA percentage was smallest (P < 0.001), but SFA and MUFA percentages were similar (P ≥ 0.505). In CD, SFA and PUFA percentages did not differ (P = 0.740), but MUFA percentage was less than both (P < 0.001). Percentages of SFA, MUFA, and PUFA in AB all differed (P ≤ 0.008) with SFA being greatest. Body condition score influenced FA composition of equine adipose tissues but to a lower extent than the type of fat depots.