Influence of vitamin E on organic matter fermentation, ruminal protein and fatty acid metabolism, protozoa concentrations and transfer of fatty acids.

Vitamin E (Vit. E) is discussed to influence ruminal biohydrogenation. The objective of this study was to investigate the influence of a Vit. E supplementation on rumen fermentation characteristics, ruminal microbial protein synthesis as well as ruminal organic matter fermentation. Furthermore, we aimed to investigate the influence of Vit. E supplementation on short-chain fatty acids (SCFA) and protozoa concentrations in the rumen and, in addition, on transfer rates of middle-chain and long-chain fatty acids into the duodenum in lactating dairy cows. Eight rumen and duodenum fistulated German Holstein cows were assigned to either a group receiving 2,327 IU/d Vit. E (138.6 IU/kg DM DL-α-tocopherylacetate; n = 4) or a control group (23.1 IU/kg DM; n = 4). Neither ruminal protein synthesis nor organic matter fermentation was influenced by treatment. Vit. E did not act on the concentrations of short-chain fatty acids and protozoa in rumen fluid. Duodenal flow of C13:0 (1.3 versus 0.2 g/d, p = 0.014) and iso-C14:0 (1.0 versus 0.5 g/d, p = 0.050) was higher in the Vit. E group. We observed a trend for higher duodenal flows for C12:0 (1.6 versus 0.9 g/d, p = 0.095) and anteiso-C15:0 (12.2 versus 8.9 g/d, p = 0.084). Transfer rate of C12:0 tended to be higher in the Vit. E group (125.61 versus 73.96, p = 0.082). No other transfer rates were affected by treatment. Further studies are necessary to investigate the influence of Vit. E on rumen microbiota and their fatty acid production as well as on the impact of different doses of Vit. E supplementation on variables of protein synthesis efficiency.

Suitability of n-alkanes and chromium (III) oxide as digestibility markers in calves at the end of the milk feeding period supplemented with a prebiotic.

Prebiotics reveal positive effects on the growth performance of pigs and poultry, and might influence intestinal microflora. This, in consequence, could alter recovery rates of digestibility markers. In the current study, we evaluated the suitability of chromium (III) oxide (Cr2O3) and the synthetic alkanes n-dotriacontane (C32) and n-hexatriacontane (C36) as external markers for digestibility estimation compared with the standard total collection method in calves supplemented with galacto-oligosaccharides. Eight male German Holstein calves (average age ± SD = 57 ± 8 days) were divided into 2 milk replacer feeding groups (group receiving galacto-oligosaccharides [A] and control group [B]). Each of 2 groups of 4 individually fed calves received a distinct milk replacer with added markers for 14 days. They were fed twice daily restrictively with milk replacer, concentrate and hay. After an adaptation period of 10 days, total faeces were collected. Faecal marker recoveries (FMR, means ± SD) for C32 were (72 ± 14)% for A and (80 ± 12)% for B. Faecal marker recoveries for C36 was (82 ± 15)% and (88 ± 13)% for groups A and B, respectively. The FMR for Cr2O3 was (102 ± 11)% and (100 ± 1)% for groups A and B, respectively. There were no significant differences between total collection organic matter digestibility and marker based organic matter digestibility when using Cr2O3 and C36. But, when utilizing C32 to calculate nutrient digestibilities, results differed from the total collection method for organic matter, crude protein and ether extract. The results indicate that Cr2O3 and C36 can be applied in digestibility studies with calves and give accurate estimates for OM and nutrient digestibilities without correction for FMR.