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

## TL;DR

This study found that antioxidant levels in milk from Brown Swiss cows are influenced by factors like lactation stage, feeding, and environmental conditions.

## Contribution

The study identifies specific animal and environmental factors affecting nonenzymatic antioxidant activity in bovine milk using large-scale data.

## Key findings

- FRAP values increase with lactation stage, parity, and during summer.
- DPPH inhibition decreases over lactation but increases with parity and ventilation.
- Feeding regimens and environmental conditions significantly influence antioxidant activity in milk.

## Abstract

Summary: This study uncovered key findings on the antioxidant activity of individual bovine milk samples based on data from 1,060 cows across 53 herds. Antioxidant capacity, measured as ferric reducing antioxidant power (FRAP) and expressed in micromolar ascorbic acid equivalents per milliliter of milk, was found to progressively increase over the course of lactation, with increasing parity and during summer. Variations in antioxidant activity were also observed based on the type of feeding regimen. The FRAP increased progressively from dry total mixed ration (TMR), to conventional feeding, and then to standard TMR, possibly reflecting differences in forage intake and botanical composition of the diet. Additionally, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, expressed as percentage inhibition, decreased over the course of lactation, and increased with parity and the presence of ventilation. These factors appear to affect specific milk components that act as radical scavengers.

Summary: This study uncovered key findings on the antioxidant activity of individual bovine milk samples based on data from 1,060 cows across 53 herds. Antioxidant capacity, measured as ferric reducing antioxidant power (FRAP) and expressed in micromolar ascorbic acid equivalents per milliliter of milk, was found to progressively increase over the course of lactation, with increasing parity and during summer. Variations in antioxidant activity were also observed based on the type of feeding regimen. The FRAP increased progressively from dry total mixed ration (TMR), to conventional feeding, and then to standard TMR, possibly reflecting differences in forage intake and botanical composition of the diet. Additionally, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, expressed as percentage inhibition, decreased over the course of lactation, and increased with parity and the presence of ventilation. These factors appear to affect specific milk components that act as radical scavengers.

•Antioxidant activity in milk is affected by both animal-specific and environmental factors.•Distinct patterns were observed between FRAP and DPPH assays.•Environmental conditions significantly modulate milk antioxidant activity.

Antioxidant activity in milk is affected by both animal-specific and environmental factors.

Distinct patterns were observed between FRAP and DPPH assays.

Environmental conditions significantly modulate milk antioxidant activity.

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.