THE INFLUENCE OF AMMONIA AND AMINES ON GRASS-SILAGE INTAKE AND INTAKEBEHAVIOR IN DAIRY-COWS

The influence of ammonia (NH3) and amines on silage dry matter intake (DMI) and milk yield was studied in 4 rumen-cannulated dairy cows. Fou r dietary treatments were studied: a direct-cut grass silage without a dditive (WAS); a formic acid (4.5 l/t) preserved silage from the same sward (FAS); and FAS with addition, just before feeding, of either 2.9 g NH3/kg dry matter (DM) (FAS + N) or 2.8 g amine/kg DM (FAS + A). In 3 successive cross-over design experiments, the diets WAS, FAS + N an d FAS + A were compared to the control diet FAS. Daily DMI was lower ( P < 0.10) for WAS, and the milk yield also tended to be lower. The DMI reduction was mainly due to reduced DMI during the first meal followi ng silage distribution (P < 0.10). Lower intake rates during this prin cipal meal (P < 0.05) suggested lower palatability of WAS. Addition of NH3 and amines to FAS did not alter milk yield, daily DMI or other va riables of intake behaviour compared to the control FAS. In the rumen, a dilutive effect by amines was suggested. In this study, a direct ro le of NH3 and amines on feed intake regulation was not established.