THE INFLUENCE OF AMMONIA, BIOGENIC-AMINES AND GAMMA-AMINOBUTYRIC-ACIDON GRASS-SILAGE INTAKE IN SHEEP

We investigated whether biogenic amines alone, or a combination of NH3 , amines and gamma-aminobutyric acid (GABA) influenced grass-silage in take, intake behaviour and rumen liquid content in sheep, Three diets were studied: a grass silage preserved with formic acid (4 litres/tonn e) (FAS), FAS with 4.9 g amines/kg DM added (FAS + A), and FAS supplem ented with a combination of N-components at the following concentratio ns: 2.7 g amines, 3.0 g NH3 and 5.0 g GABA/kg DM (FAS + C), The diets were offered ad libitum, once daily to six rumen-cannulated Texel weth ers in a crossover design, Daily DM intake (DMI; g DM/d) tended to be influenced by diet (P = 0.08). The DMI of FAS + A was similar to that of FAS alone, whereas that of FAS + C tended to be higher, The mean ra te of ingestion (g DM/min) over all feeding bouts tended to be the Low est for FAS + A (P = 0.06). No differences were found among the diets concerning intake behaviour during the principal meal, Average intake rate of the small meals tended to be the lowest for FAS + A (P = 0.06) . Although rumen NH3 concentration was higher (P < 0.05) after the pri ncipal meal, rumen pH, osmolality, rumen pool size and liquid content were not significantly altered by adding amines or the mixture of N-co mponents to FAS, We conclude that biogenic amines or N-containing prod ucts of protein fermentation in concentrations normally found in poor- quality silages do not reduce the intake of well-preserved formic acid -treated silage. A direct effect on chemostatic regulation of intake w as not observed, but a slight negative effect on silage palatability c annot be excluded.