Protein supplementation for lactating cows in pasture of Mombaça grass (Megathyrsus maximum cv. Mombaça)

The objective of this study was to evaluate the performance and metabolic parameters of crossbred lactating cows under intermittent grazing on Megathyrsus maximum cv. Mombaça with protein supplementation in three different proportions. Twelve lactating crossbred multiparous cows, grouped in randomized blocks, received supplementation in three proportions of crude protein (CP): 9, 15 and 21% DM in the concentrate, for 60 days. Milk yield, fat, protein, casein, lactose, defatted dry extract and total solids content were not influenced (p>0.05) by the crude protein content of the concentrates. Milk yield corrected for 4% fat, linearly decreased (p<0.05) with the increase in CP content of the concentrates. Values of urea and urea nitrogen in plasma were higher for treatments with 15 and 21% CP. The values of albumins, globulins, hemoglobin, and total proteins were not influenced (p>0.05) by the crude protein levels. It is concluded that the increase in crude protein levels in the concentrate in the diet of lactating cows grazing on Mombaça grass influences productive and metabolic parameters. It is recommended a level of 9% Crude Protein.