Productive and metabolic response to two levels of turnip (Brassica rapa L.) supplementation in grazing dairy cows during summer

Abstract

Forage turnip (Brassica rapa L.) is used as a supplementary feed for grazing cattle in summer. The aim of this study was to evaluate the effect of two levels of forage turnip supplementary feed on milk production, and energy and protein metabolic responses in grazing dairy cattle during summer. 16 randomly distributed Chilean Black Friesian cows were used in two treatments: diet A (2.6 kg DM cow-1) and diet B (5.1 kg DM cow-1). The milk production in cows fed on diet A presented no statistical difference with those fed on diet B. Milk protein and milk fat were similar between the two treatments (p > 0.05). Both turnip diets maintained an adequate protein and energy balance, reflected in plasma βHB, total protein, albumin and urea concentrations within the reference intervals. No differences in yield responses were found between the two treatments under the study conditions. Similarly, no effects were observed on milk composition, while a normal energy balance was maintained. Hypophosphatemia was observed in cows fed on diet B.