R. Keusenhoff, J. Voigt, B. Piatkowski
Archiv fur Tierernahrung
The influence of the replacement of cereals by sugar beet in the rations was tested with 6 calves supplied with re-entrant duodenal or ruminal cannulae in 4 measuring periods between their 11th and 17th weeks of life. The control ration (A) consisted of 60% mixed feed, 20% hay and 20% wilted silage, the test ration (B) consisted of 30% mixed feed, 33% sugar beet, 20% hay and 17% wilted silage. A contained 15% crude protein, 32% starch and 2% sugar, B in the same sequence 14, 12 and 24% (amounts in % of DM). The following results were achieved: The functional development of the rumen is largely completed three weeks after weaning. There were no qualitative changes between the 11th and 17th weeks of life. The fermentation of organic matter in the rumen (50...52%) and bacterial protein yield (2.4...2.6 g N per 100 g digestible organic matter) corresponded to that of adult ruminants. The partial replacement of cereals by sugar beet resulted in a significant increase of the molar butyric acid quota to 20.8% (B) in comparison to 13% (A) with the same level of total volatile fatty acids in the rumen, the decrease of the quota of acetic acid to 61.4% (B) in contrast to 73.5% (A) and the reduction of the ruminal NH3 concentration after feeding. The feeding of sugar beets had a positive influence on the passage of starch in the duodenum. The DM-degradation of straw in polyamide bags was also positively influenced. 62.6% (A) and 73.9% (B) of the feed N were degraded in the forestomachs. Per kg DM intake 29.8 g (A) and 28.0 g (B) non-ammonia-N (NAN) were detected at the duodenum. 54% (A) and 64% (B) of NAN consisted of bacteria N. In contrast to adult ruminants at nutrition level 1 (maintenance) a considerable net influx of endogenous N into the rumen was to be observed at a crude protein concentration in the feed of 14 to 15% (in the DM) in both groups. Accordingly, the minimum protein content of the ration (in the DM) should be above 15% in the rearing range studied.