The Effect of Replacing Wheat Straw with Soybean Straw on Feed Intake, Rumen Fermentation, Correlation between Neutral Detergent Fiber (NDF) Digestibility and Cellulose Activity Enzymes in Atabai Ewes

After the harvesting of agricultural products, including soybeans, waste remains that is not used for human consumption and can be used to feed ruminants. Therefore, the impact of replacing soybean straw with wheat straw on feed intake, ruminal fermentation, and cellulase enzyme activity in Atabai ewes was inves-tigated im the current study. Eighteen ewes with an initial weight of kg were used in a compeletly random-ized design in three groups, each of which included 6 ewes, for 42- day feeding period. The experiment treatment were: 1) control diet (without soybean straw), 2) diet with 20% soybean straw, and 3) diet with 40% soybean straw. The daily feed intake was calculated from the difference between the given feed and the post-manger feed. In order to measure rumen fermentation and the rumen protozoan population, volatile fatty acids (VFA) and cellulase enzyme activity, rumen fluid samples were taken from the animals in the last days of the experiment. The results showed that dry matter intake in ewes fed with 20 and 40% soybean straw was increased. No significant difference was observed between the different treatments in terms of rumen pH, protozoa and ammonia nitrogen (P<0.05). The particulate material and total activity of carboxy methyl- cellulose (CMM) and the microcrystalline-cellulase activity (MCC) were affected by inclusion of soybean straw in feed (P<0.05). There was no significant difference in the amount of VFA, acetate, bu-tyrate, isobutyrae, valeret, butyrate among the experimental groups (P>0.05), whereas propionate increased with increasing amount of soybean straw in the diet (P<0.05). Also, the ratio of acetate to propionate de-creased with increasing dietary level of soybean straw (P<0.05). These results suggest that soybean straw can be used as a forage source to completely replace wheat straw in ewes' diets.