Evaluation of Fatty Acid Distributions and Triacylglycerol Species in Sow Milk and Commercial Piglet Formulas: A Comparative Study Based on Fat Sources and Lactation Stages

SIMPLE SUMMARY: Fat ingredients used in piglet formulas differ from sow milk fats in fatty acid compositions and triacylglycerol (TAG) species, and therefore may be less optimal for piglet growth. It is necessary to well-define fat characteristics (including fatty acid distributions and triacylglycerol species) of sow milk in a sufficient number of samples, as well as lipid profiles of piglet formulas. Total fatty acid and sn-2 fatty acid compositions, and triacylglycerol species in sow colostrum, sow milk, and piglet formulas were analyzed in the present study. Colostrum, milk, and piglet formula samples were notably distinguished into three groups based on their fatty acids and triacylglycerols, among which triacylglycerols were the most differentiated index. The results are beneficial for providing inspirations for production of sow milk fat equivalents. ABSTRACT: Total fatty acid and sn-2 fatty acid compositions, and triacylglycerol (TAG) species in 130 sow colostrum, 100 sow milk, and 22 piglet formula samples were analyzed in the present study. Significant differences were found in concentrations of medium chain-saturated fatty acids (MC-SFAs) and distributions of palmitic acid (P) and oleic (O)/linoleic (L) acid. The levels of MC-SFAs in sow colostrum and sow milk fats (2.4–3.1%) were significantly lower than those in piglet formulas (7.9–27.2%). Approximately 63% of palmitic acid was located at the sn-2 position in both sow colostrum and milk fats, which was significantly higher than in piglet formula fats (21.1–39.1%). Correspondingly, only 17.8–28.3% of oleic and linoleic acids were at the sn-2 position in sow milk fats, contributing to their typical triacylglycerol structure in sow colostrum and milk, whose palmitic acid connected to the sn-2 position and unsaturated fatty acids located at the sn-1,3 positions. Sow colostrum, milk, and piglet formulas were notably distinguished into three groups based on their fatty acids and TAGs, among which triacylglycerols were the most differentiated index. A total of 51 TAG species (including their isomers) differed significantly between sow colostrum and milk and piglet formulas. OPL and OPO were the most important differentiating TAGs. The large amount of sn-2 esterified palmitic acid plays a key role in improving the absorption of fat and calcium. The results provide suggestions for design of sow milk fat equivalents.