Nutrient composition of mistletoe (Viscum album) and its nutritive value for ruminant animals

摘要

Mistletoe (Viscum album L. subsp. album) is known as an obligatory hemiparasite of trees and is consumed by herbivores in some places, especially during periods of forage shortage and drought. This experiment was conducted to determine nutrient composition and nutritive value of mistletoe with respect to vegetation stage. Mistletoe samples were collected from three different tree species [almond (Amygdalus communis L.), plum (Prunus domestica L.), and willow (Salix alba L.)] at three different vegetation stages (April, July, October) naturally growing in Central Turkey. Five samples were taken at each vegetation stage for each tree species. The samples were incubated in rumens of two 2-year old fistulated Holstein cows. Nutrient data and nutritive value indices were subjected to 2-way ANOVA using the GLM procedure. Crude protein and NDF concentrations and metabolisable energy level of the samples were in the ranges of 52.5–68.6, 291–330, and 7.8–8.4 MJ kg−1 DM, respectively. There were also significant differences in DM, crude ash, Fe, Cu, and Zn levels among trees. As the vegetation progressed, there were linear decreases in DM, CP, and NDF and linear increases in ADF, Ca, Cu, and Zn levels. There were significant interaction effects for tree species by vegetation stage in terms of DM, ADF, and Zn. In vitro dry matter and organic matter digestibility coefficients were between 0.84 and 0.87 and between 0.52 and 0.55, respectively. It was also observed that degradation of V. album was almost completed after the first 48 h. The soluble and readily degraded portion of DM (fraction “a”) increased, whereas the insoluble but degradable portion of DM (fraction “b”) decreased with advancing vegetation stage. Effective degradability of dry matter (EDDM) also increased significantly as the vegetation progressed. Gas production from fraction “b” varied by tree species and the stage of vegetation. A significant interaction of tree species by vegetation effects on EDDM and gas production was also noted. After 48 h, cumulative gas production and fraction “b” ranged from 52.71 ml to 58.85 ml and from 48.8 ml to 75.4 ml, respectively. In general, the mistletoe was low in protein, moderate in fibre, and high in minerals. In conclusion, as long as a lack of deleterious effects on health and performance is shown in feeding trials, mistletoe has potential to be used as a dietary component in ruminant feeding.