EFFECT OF INCLUDING BARLEY OR MOLASSED SUGAR-BEET FEED IN GRASS-SILAGE DIETS ON THEIR DIGESTION BY CATTLE AND SHEEP

The objective of the experiment was to compare the digestion of barley, a starch-based feedingstuff, with molassed sugar beet feed (SBF), a high-fibre, sugar-containing feedingstuff, when fed to cattle and sheep receiving silage. There were between-species differences in rumen measurements. Sheep had higher mean daily rumen ammonia-N concentrations; the molar proportions (mmol mol-1 total rumen volatile fatty acids) of propionic acid were higher and those of n-butyric acid lower in sheep than in cattle. The feeding of barley was associated with increased rumen populations of protozoa and increased rumen ammonia-N concentrations compared with the feeding of SBF. There were no significant differences between the diets fed in whole tract or rumen digestion of organic matter or nitrogen. However, feeding SBF tended to increase the quantities of non-ammonia-N and microbial N entering the small intestine daily; feeding barley did not improve N flow to the small intestine.