Impact of animal and herd factors on the nonenzymatic antioxidant potential in milk from individual Brown Swiss cows

The objectives of this study were to (1) characterize the nonenzymatic antioxidant activity of individual bovine milk samples using 2 assays: ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), and (2) investigate the effects of animal (DIM, parity, and daily milk yield [DMY; kg/d]) and environmental factors (temperature-humidity index [THI], season, ventilation, feeding, and altitude) on these traits. Milk samples were collected once during evening milking from 1,060 Brown Swiss cows across 53 herds in Northern Italy. Antioxidant activity was expressed as micromolar ascorbic acid equivalents per milliliter of milk for the FRAP and as a percentage of DPPH inhibition. Both traits in milk were influenced by a range of animal-related and environmental factors, with varying degrees of impact. The FRAP values were highest in primiparous cows and decreased with increasing parity. In contrast, DPPH inhibition was greatest in tertiparous cows, followed by primiparous and secondiparous cows. Days in milk had a significant effect on DPPH, which declined as lactation progressed. A positive association was observed between DMY and FRAP values, with FRAP increasing up to approximately 25 kg/d, beyond which it plateaued. Among the environmental factors, the lowest FRAP values were observed in summer and in herds fed a dry TMR. Furthermore, milk from herds equipped with ventilation systems showed slightly higher DPPH inhibition compared with those without such systems. These findings offer valuable insights into factors affecting antioxidant properties in bovine milk and underscore the need for further research into other nonenzymatic antioxidants and their concentrations. Future studies should investigate the genetic basis of milk antioxidant properties, examine their relationship with milk composition, and evaluate the consequences for animal health and product quality.