The Effect of Low-Temperature Crystallization of Fish Oil on the Chemical Composition, Fatty Acid Profile, and Functional Properties of Cow’s Milk

SIMPLE SUMMARY: Nowadays, both consumers and producers are paying increasing attention to the health-promoting properties of food (functional food). Wide and multi-directional pro-healthy effects are shown by long-chain unsaturated omega-3 fatty acids (mainly eicosapentaenoic (EPA), and docosahexaenoic (DHA) ones) and conjugated linoleic acid dienes (CLA). On the other hand, saturated fatty acids (SFAs), particularly medium-chain ones, have adverse atherogenic and thrombogenic effects. The supplementation of dairy cows’ rations with fish oil subjected to low-temperature crystallization (LTC-FO) enriched with long-chain polyunsaturated fatty acids reduced milk fat yield and concentration and profitably modified the fatty acid profile. The level of SFAs, especially short- and medium-chain ones, in milk fat decreased. In turn, the content of polyunsaturated fatty acids (PUFAs), including biologically active ones like eicosapentaenoic (EPA), docosahexaenoic (DHA), CLA, and trans-vaccenic acid (TVA), increased. In conclusion, LTC-FO could be used to modify the nutritional and health value of milk. ABSTRACT: The study aimed to investigate the effect of supplementation of fish oil after the process of low-temperature crystallization (LTC-FO) enriched with long-chain polyunsaturated fatty acids (LC-PUFAs) on cow milk parameters. The experiment was carried out on 24 Polish Holstein Friesian cows. For 4 weeks, experimental (EXP) group animals (n = 12) were fed LTC-FO (1% of dry matter). Milk was collected two times: on days 14 and 30. LTC-FO supplementation decreased milk fat yield and concentration (p < 0.01). Higher levels of polyunsaturated fatty acids (PUFAs), including these with beneficial biological properties, i.e., eicosapentaenoic (EPA), docosahexaenoic (DHA), docosapentaenoic (DPA), CLA, alpha-linolenic acid (ALA), and TVA (p < 0.01), and lower levels of SFAs, especially short- (p < 0.01) and medium-chain ones (p < 0.05, p < 0.01), were found in the EXP group. The addition of LTC-FO reduced the value of atherogenic and thrombogenic indices as well as SFA/UFA and n-6/n-3 ratios and increased the content of n-3 PUFA and functional fatty acids (p < 0.01). The addition of LTC-FO also increased the delta-9 desaturase index for CLA/TVA and decreased it for pairs C14:1/C14:0 and C16:1/C16:0 (p < 0.05, p < 0.01).