Effect of a high forage: Concentrate ratio on milk yield, blood parameters and oxidative status in lactating cows

A feeding strategy that requires a forage: concentrate ratio equal to 70: 30, with at least five different herbs in the forage and the use of silages prohibited, has recently been introduced in Italy. Despite the benefits in terms of human health (lower ω6: ω3 ratio, higher conjugated linoleic acid level) of the obtained milk, little information regarding the possible effects on cows' health is available. The aim of this study was to evaluate the effects of such a feeding strategy in dairy cows (90 days in milk at the beginning of the trial) on milk yield and composition, and blood metabolic profile, including the evaluation of oxidative stress. The proposed feeding strategy, compared with a semi-intensive strategy, resulted in an improvement of animal oxidative status (lower levels of reactive oxygen metabolites, higher levels of antioxidant potential and anti-reactive oxygen metabolites) and a significant increase of milk urea only in the first part of the trial. No differences in milk yield and composition were detected throughout the trial.