The effect of replacing alfalfa hay with sesbania straw (Sesbania sp. L) on the digestive and fermentation activity of anaerobic bacteria and fungi isolated from the rumen of sheep

The purpose of this research was to compare the nutritional value of sesbania straw with alfalfa hay and determine its effects on the digestive and fermentation activity of the ruminal anaerobic bacteria and fungi. The experimental diets included a control diet (without sesbania straw) and diets in which alfalfa hay was replaced with sesbania straw at the rate of 25, 50, 75, and 100% in a fattening lamb diet. The in vitro digestibility of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) was the highest (P 0.05) in the control diet (P 0.05), but not different from the diets containing 25, 50 and 75% of the sesbania straw in lieu of alfalfa hay (P 0.05). The digestibility of dry matter, NDF, and ADF of alfalfa hay was higher than that of sesbania straw (P 0.05). Compared to the control diet, the replacement of sesbania plant with alfalfa hay up to 75% level did not have a significant effect on the digestibility of DM, NDF, and ADF by isolated rumen bacteria and fungi, but at 100% replacement, the digestibility decreased (P 0.05). Also, in the culture medium of isolated rumen bacteria and fungi, alfalfa hay had more digestibility of the nutrients than sesbania straw (P 0.05). The pH and ammonia nitrogen concentration of the culture medium containing the isolated rumen bacteria and fungi were significantly higher in the control diet than in the diets containing sesbania straw (P 0.05). In general, the findings showed that it is possible to replace at least 75% of alfalfa hay with sesbania straw in the diets of fattening lambs.