NUTRITIONAL COMPOSITION OF Arceuthobium vaginatum subsp. vaginatum AND A. globosum subsp. grandicaule AND THEIR EFFECT ON IN VITRO RUMINAL FERMENTATION KINETICS

Background: Arceuthobium vaginatum subsp. vaginatum (BM; black mistletoe) and Arceuthobium globosum subsp. grandicaule (YM; yellow mistletoe), are two parasitic plant species abundant in the forests of northern and central Mexico and Central America, affect 43% of the P. hartwegii tree population in the Nevado de Toluca Flora and Fauna Protection Area (NTFFPA), including mistletoe as a complementary feed in sheep can reduce the environmental impact generated by these pests to the forest and also reduce the purchase of feed for livestock. Objective: To evaluate the chemical composition, phenolic content and in vitro fermentation kinetics of two mistletoe species (M) Arceuthobium vaginatum subsp. vaginatum (BM; black mistletoe) and A. globosum subsp. grandicaule (YM; yellow mistletoe), in four age categories (AC) of Pinus hartwegii (AC: small sapling, large sapling, juvenile and adult) collected in the Nevado de Toluca Flora and Fauna Protection Area (NTFFPA). Methodology: The chemical composition (dry matter DM; neutral detergent fiber NDF; acid detergent fiber ADF and crude protein CP), phenolic content (total phenols TP; total tannins TT and condensed tannins, CT), in vitro fermentation kinetics parameters and in vitro digestibility were analysed. The experimental design used was completely randomized design with 2x4 factorial arrangement. Results: DM content was different between M (P< 0.05), the highest was found in BM. The NDF and ADF content was different between M, ranging from 364.45-467.43 g/kg DM. No differences (P>0.05) were observed in CP which averaged 62.08 g/kg DM. The TP, TT and CT content was different between M (P<0.05), the highest content was in YM with no effect observed in AC. B-gas production (mL of gas) presented differences between M and AC sampled (P<0.05). The gas production rate c on average was 0.042. Lag time was different between M (P<0.05). The in vitro digestibility of dry matter and organic matter were different between M (P<0.05). Implications: The results reported here serve as a tool for decision making on its possible inclusion as a forage addition to a diet in sheep feeding. Conclusions: The chemical composition and in vitro digestibility was different between M and the AC, contain secondary metabolites such as total phenols and condensed tannins and have an impact on in vitro fermentation.