NUTRITIONAL VALUE OF SOME RARE FORAGE PLANTS FED TO SMALL RUMINANTS

Abstract

Background: There are some plants in the global rangelands whose nutritional value is still unknown to animal nutritionists. Objective: This study aimed to evaluate the in vitro value of some rare plants including Marrubium vulgare L., Ceratocarpus arenarius L., Gypsophila paniculate L., Ferula gummosa Boiss., and Centaurea virgate Lam. that are consumed by livestock. Methodology: The fresh samples were collected from Iran about mid-June, after the flowering stage. Buffering capacity, chemical and mineral compounds of plants were determined according to the standard methods. An in vitro media was also used to measure some fermentation parameters. Results: There were significant differences in chemical composition and mineral contents among the plants. The higher CP content was found in M. vulgare (173.8 g kg-1 DM) and C. arenarius (140.1 g kg-1 DM), respectively. The lowest ADF (166.6 g kg-1 DM)‌, NDF (294.9 g kg-1 DM), and ADL (74.9 g kg-1 DM) contents were recorded in M. vulgare. ‌C. arenarius exhibited the lowest DMD (473.3 g kg-1 DM), ME (4.12 MJ kg-1 DM), RFV (99.46), and gas volume at 24 h (13.57 ml) which were significantly different from all other plant species. The calcium content ranged from 18.15 for C. virgata to 37.62 g kg-1 DM for G. paniculata. The highest Na (0.64 g kg-1 DM), K (24.60 g kg-1 DM), Co (3.07 mg kg-1 DM), and Fe (756.53 mg kg-1 DM) were observed in M. vulgare. With the addition of G. paniculata to the culture medium, a noticeable increase in TVFA (40.65 mM L-1) concentration was observed. The highest acid-base buffering capacity was obtained in G. paniculata (191.64 mEq×10-3). Inclusion of C. virgata gave significantly higher acetate (64.07%) and butyrate (14.83%) concentration and lower propionate (19.17%) concentration in the culture medium. Implications: The available data can take into account in preparing a balanced diet, especially for sheep grazing in the pasture. Due to the secondary metabolites, the forage value of these plants should also be evaluated in the form of in vivo experiments with long-term experiment periods. Conclusion: According to the in vitro results, when these plants are fed together with a diversity of good quality forage, they can provide part of the nutrient requirement for small ruminant in Iran.