Effect of Multispecies Swards on the Fat Composition and Oxidative Stability of Milk from Dairy Cows in Mid-Late Lactation

Multispecies swards have been recognized as more sustainable than traditional ryegrass systems, in addition to providing a range of phytochemicals to the ruminant diet. In this regard, polyphenols may be linked to higher levels of bioactive fatty acids in milk and enhanced nutraceutical properties in dairy products. This study compares the fat composition and oxidative stability of milk produced by cows fed on multispecies swards (MULTI) with milk from two conventional swards [a perennial ryegrass monoculture (PRG) and a mixture of perennial ryegrass and white clover (PRG + WC)] during the Irish summer. Milk from cows fed on MULTI had the highest concentrations of polyunsaturated fatty acids (36.83 mg/g) and bioactive fatty acids (p < 0.05). In contrast, milk from cows fed on PRG contained the highest mean concentrations of monounsaturated (284.68 mg/g) and saturated fatty acids (783.45 mg/g) (p > 0.05). β-Carotene and α-tocopherol were higher in milk produced by cows fed on PRG (15.29 and 10.18 mg/kg, respectively), resulting in milk with a lower TBARS value (1.33 mg/kg) (p < 0.05). This study indicates that MULTI might be utilized as an alternative to conventional swards while providing higher levels of bioactive fatty acids in milk that are associated with consumer health.