Effect of feeding Ziziphora clinopodioides‌ to finishing lambs on the activity of rumen fungi and bacteria in digestion and fermentation of sugarcane top

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The aim of the present study was to investigate the effect of using Ziziphora clinopodioides in the diet of fattening lambs on the activity of rumen bacteria and fungi in the in vitro digestibility of sugarcane top. Three experimental diets containing Ziziphora clinopodioides at the levels of 0, 0.2 or 0.4% were fed to 15 finishing lambs (about seven months, 40 kg weight) for 30 days. At the end of the experiment, the rumen fluid of the lambs was taken through a stomach tube. After separation and purification of the bacteria and fungi populations from the rumen fluid, their effects were investigated on the digestion and fermentation of sugarcane top in a specific medium cultureof bacteria or fungi. The results showed that the gas production potential of sugarcane top by ruminal fungi was significantly higher in the treatments containing Ziziphora clinopodioides (P<0.05). Ammonia nitrogen concentration, pH, and the disappearance of dry matter and NDF of sugarcane top in fungi medium culture were not affected by experimental treatments. The ammonia nitrogen concentration in bacteria medium culture was decreased after 72 h incubation and the lowest concentration was observed in treatment containing 0.4% of Ziziphora clinopodioides (13.6 mg/100 mL) (P<0.05). In comparison to the control, the disappearance of dry matter and NDF of sugarcane top from bacteria medium culture after 24 h incubation was significantly higher in the diets containing Ziziphora clinopodioides, and the highest disappearance of dry matter (55.62%) and NDF (44.5%) wereobserved in treatment containing 0.4% of Ziziphora clinopodioides. Overall, feeding the Ziziphora clinopodioides supplement to finishing lambs had no effect on digestion of sugarcane top by rumen fungi, but led to an increase in the potential of gas production. On the other hand, the Ziziphora clinopodioides resulted in increase of the nutrients’ disappearance of sugarcane top by rumen bacteria only at time 24 h of incubation.