In vitro rumen fermentation kinetics and nutritional parameters of some native range plants and their relationships to gas production

摘要

The study was achieved to estimate the in vitro rumen fermentation characteristics (initial gas produced from soluble fraction; a, gas produced from insoluble but fermentable fraction; b, potential gas production; a + b, fractional rate of gas production per hour; c), effective degradability, nitrogen solubility and chemical composition of five native drought-tolerant range perennial shrubs, and study their relationships with gas production parameters after incubation with rumen fluid in the absence or presence of polyethylene glycol (PEG, 6000). The in vitro potential gas production (mL/g DM) and effective degradability of dry matter (%) values were highest (P 0.05) in Capparis spinosa (250 mL and 31%), lowest in Artemisia herba-alba and Noaea mucronata (149 mL and 20%), and intermediate in Lavandula officialis andAstragalus spinosus (186 mL and 24%), respectively. L. officialis, N. mucronata and A. herba-alba had higher (P 0.05) fractional rate of gas production (0.087 mL/h) than other species (0.075mL/h). Nitrogen solubility values ranged from 37% to 52%, with C. spinosa having the highest value. The greatest proportion of gas production occurred during the first 24 h of incubation. Gas production after 24 h of incubation and estimated fermentation parameters (a, b and a + b) were positively correlated with nitrogen solubility and crude protein but negatively correlated with tannins, total phenols, lignin and neutral-detergent fibre. The addition of PEG to the plant samples incubated with rumen fluid at a ratio of 2:1 PEG: substrate did no increase the values of gas production, characteristics of fermentation and effective degradability of dry matter. On the basis of the studies on nutritive parameters, the evaluated species were nutritionally well suited as supplements for ruminants in arid regions.