A NOTE ON THE EFFECT OF FORAGE TYPE ON THE YIELD, CHEMICAL-COMPOSITION AND CLOTTING PROPERTIES OF MILK

Twenty-five primiparous cows in mid lactation were used in a 2 X 2 Lat in-square design experiment. During each 3-week period, cows were offe red a diet composed either of grass silage (8.3 kg dry matter (DM) per day) or hay (10.5 kg DM per day). Each diet was supplemented with a m ixture of barley, soya-bean meal and urea in proportions calculated to keep the overall rations isocaloric and isonitrogenous. Cows offered grass silage produced more milk (+1.7 kg/day, P < 0.01) with less fat and protein (-1.3 g/kg and -0-8 g/kg, respectively, P < 0-01) than tho se offered hay. All animals gained weight, but they gained more with t he hay diet than with the grass silage diet. The rheological parameter s of milk were similar in both groups. Rumen juice of cows offered hay had higher concentrations of acetic acid and slightly lower concentra tions of propionic and butyric acid (P< 0-01) than cows offered grass silage.