Impact of Bovine Lipocalin-2 Gene on the Antioxidant Activity of Milk from Polish Holstein-Friesian Cows

SIMPLE SUMMARY: Recently, an increased interest in high health-value food products rich in natural antioxidants has been observed. Milk and milk products are one of the richest sources of biologically active compounds with antioxidant properties in products of animal origin. Lipocalin-2 (LCN2) is a small secreted protein, which is involved in inflammatory processes. Due to the fact that LCN-2 can be produced by various types of cells in response to oxidative stress and LCN2 gene polymorphism has been associated with the somatic cells count in cow’s milk, the aim of this study was to validate the association of LCN2 polymorphism with antioxidant activity of milk from Holstein-Friesian cows. Four single nucleotide polymorphisms (SNPs) was identified, one of which g.98793763G>C was associated with higher antioxidant capacity in milk. The antioxidant capacity of milk also varied according to the age of cows, their daily milk yield, and somatic cell count (SCC) in milk. ABSTRACT: In the recent years, antioxidant properties of food products have become an important aspect for consumers. Milk is a very good source of easily absorbable proteins and minerals, as well as a valuable source of antioxidants. Lipocalin-2 (LCN2), given that, inter alia, it is produced in large quantities by various types of cells in response to oxidative stress caused by physical or chemical factors, it can be considered a protein that determines the total antioxidant capacity of milk. The main objective of this study was to analyze polymorphisms within the lipocalin-2 gene and to determine their impact on antioxidant activity of milk from Holstein-Friesian cows. The genotyping was carried out by sequencing of PCR products. To determine the antioxidant activity of milk, the Trolox equivalent antioxidant capacity (TEAC) method was used. A total of four polymorphic sites were identified in the examined segment of the bovine lipocalin-2 gene. It was shown that cows of the CC genotype at the locus g.98793763G>C produced milk of significantly higher antioxidant capacity. The antioxidant capacity of milk also varied according to the age of cows, their daily milk yield, and SCC in milk.