During 1996 and 1997 twenty-four Friesian spring calving cows where divided into three lots of 8 cows, grazing of Lolium perenne and Trifolium repens pastures, 2.6 kg of concentrate and three levels of maize silage (2.24, 1.12 and 0 kg of DM cow and day), from March to September.
The addition of silage increased the intake of dry matter (P<0.05), but not the pasture (every kg of silage replaced 0.63 and 0.51 kg of pasture for diets of 2.24 and 1.12 kg respectively). The production of milk, protein, fat and non‑fat solids was 22.85, 3.7%, 3.87% and 8.41%, 19.83, 3.09%, 3.98% and 8.84%, 24,21, 2.93%, 3.98% and 8.4% for the t reat ment 2,24; 1.12 and 0 kg of maize silage.
The concentration of N‑NH₃ of ruminal liquid was lower (P<0.05) with 2.24 kg, showing no differences of pH between diets.
We can conclude that the adition maize silage the pasture improvement significantly better the containt of protein in the milk.