Evaluation of nutritive value of perceptible compounds of corn-steep liquor by ‎tannins extracted from raisin by-products as a protein source in ruminant nutrition

This experiment was designed to survey the nutritive value and estimate protected-protein level of Protanomix as a new protein source and compare it with soybean meal. Protanomix is a brown powder by separating the precipitate produced from the reaction of tannin with corn-steep liquor. Crude protein (CP) and metabolizable energy (ME) in this protein source is nearly similar to soybean meal, and more than 80% of its protein content is insoluble. In this study, potential of in vitro gas production in Protanomix was significantly (P˂0.001) lower than the control treatment (soybean meal); however, substitution of soybean meal at different levels of Protanomix in experimental diets did not lead to significant changes in gas production parameters (P˃0.05). Comparing Protanomix with soybean meal (control) showed that in vitro truly degraded dry matter (IVTDDM), estimated metabilizable energy (ME) and pH were similar (P˃0.05). However, short chain fatty acids (SCFA), apparently in vitro organic matter digestibility (IVOMAD) and ammonia nitrogen (N-NH3) were significantly higher in soybean meal (P˂0.01) than Protanomix, while partitioning factor (PF), microbial protein synthesis (MPS) and efficiency of microbial protein synthesis (EMPS) were greater in Protanomix than soybean meal (P˂0.05). Nonetheless, when soybean meal was substituted with different levels of Protanomix in the experimental diets, only concentration of ammonia nitrogen (N-NH3) was significantly decreased (P˂0.001).