Comparative study of forestomach digestion in llamas and sheep.

To compare digestion in the forestomach of llamas and sheep, the animals were fed four different diets: hay alone (H), low in nitrogen; the same hay with soybean meal (HS), with barley (HB) and with both soybean meal and barley (HSB). The sheep intakes were restricted to obtain about the same intake level in the two species. On average, the digestibilities of DM, OM and NDF were significantly higher in llamas: respectively, +2.7, 3.6 and 5.3 for the four diets. Added barley impaired hay digestion in the sheep, but very little in the llamas. The llamas retained nitrogen better than the sheep owing to very low urine losses. For hay alone, the retention time of digesta in the forestomach was higher in the llamas than in the sheep. In contrast, there was no difference between species for the other diets. The pH and ammonia levels were higher in llamas. In contrast, the SCFA levels were lower. In all cases the in-situ rate of digestion was greater in llamas. The low intake of llamas generally observed in the literature does not account for their better digestion. The stability of the two first compartment pH levels and an excellent cellulolytic activity are determining factors in the better digestion efficiency of plant cell walls in the llamas. However, higher NH3 levels were observed in llamas, although the urinary N excretion was lower.

The influence of ammonia, biogenic amines and gamma-aminobutyric acid on 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 intake, intake behaviour and rumen liquid content in sheep. Three diets were studied: a grass silage preserved with formic acid (4 litres/tonne) (FAS), FAS with 4.9 g amines/kg DM added (FAS+A), and FAS supplemented with a combination of N-components at the following concentrations: 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 wethers 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 rate of ingestion (g DM/min) over all feeding bouts tended to be the lowest 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 principal meal, rumen pH, osmolality, rumen pool size and liquid content were not significantly altered by adding amines or the mixture of N-components to FAS. We conclude that biogenic amines or N-containing products 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 was not observed, but a slight negative effect on silage palatability cannot be excluded.