Performance of crossbred lactating cows at grazing in response to nitrogen supplementation and different levels of concentrate feed

Abstract

The performance of crossbred (1/2 Holstein x Zebu) cows supplemented on Brachiaria decumbens pasture during the wet-dry transition period was evaluated. Eight cows with 497±50kg, during third and fourth lactations and after the lactation peak were distributed in two 4 x 4 Latin squares. The treatments consisted of a factorial with two types of mineral supplements (nitrogenous and mineral salt) and two levels of concentrate (0.3 and 0.6% body weight (BW)/cow/day), based on corn and soybean meal (60:40), and supplied during the morning and afternoon milking. The experiment lasted 56 days, divided into four periods of 14 days, with seven days for adaptation and seven for data collection. No interaction (P > 0.05) was observed between the supplements and the concentrate levels. The nitrogenous salt and the highest concentrate level increased (P < 0.05) the intake of crude protein, and the highest concentrate level increased (P < 0.05) the intake of non-fibrous carbohydrates and the digestibility of crude protein. No effect (P > 0.05) of supplement and concentrate level was observed on the milk constituents and feed efficiency. Grazing crossbred after the lactation peak during the wet-dry transition period achieve the productive potential with 0.3% BW of concentrate per day and mineral salt.