Effect of some phytoextracts on in vitro rumen digestion

Plant secondary compounds, generally considered in the past as antinutritional factors, can be worth to be tested in animal production systems as alternative to traditional chemical allopathic drugs and to enhance animal health and performance but, in ruminants, attention should be paid for possible interference with rumen metabolism. Particular interest assume phytoextracts with claimed antioxidant, antinflammatory or immunomodulant potential. Five plant extracts from Curcuma longa, Andrographis paniculata, Ginko biloba, Salix chilensis and Echinacea angustifolia were tested in vitro for their possible effect on rumen fermentations and feeds digestion. The trials were carried out by the Ankom DaisyII incubator, testing three concentrations of each extract (20, 60 and 120 mg/L). Corn meal, grass hay, alfalfa hay and beet pulp were incubated in F57 bags. Dry matter digestibility, pH, ammonia and VFA concentration were measured after 48 h of incubation. S. chilensis slightly reduced pH (P<0.05). G. biloba and S. chilensis did not affect feeds dry matter digestibility, that was increased by the addition of A. paniculata in fibrous feeds in a dose dependent manner, but not in corn meal. On the contrary, C. longa extract slightly but significantly reduced digestibility of all feeds samples and also ammonia concentration. All plant extracts did not significantly alter VFA concentration, suggesting a possible effect on microbial efficiency: ameliorated by A. paniculata and lowered by C. longa. All the tested plant extracts did not induced major changes in rumen metabolism, at least when evaluated in vitro, and can be candidates for in vivo utilisation. Nevertheless, their in vivo effects should be tested, mainly for long lasting utilisation and with attention to their possible consequences on whole digestive tract.