Comparison of nutritive value of different protein sources resulting from the reaction of tannins extracted from raisin byproducts with corn-steep liquor in ruminant nutrition

This experiment was designed to determine the nutritive value and estimate the rumen protected-protein level of protanomix and phosphoprotanomix as two new protein sources and compare them with corn-steep liquor as a raw material used for the production of these products. These two powdery products are obtained by separating and drying precipitates produced by reaction of tannins with corn-steep liquor. Tannins and total phenolic compounds contents in raisin-stem extract were 22.37 and 30.07 percent of dry matter, respectively. The insoluble protein in protonomix and phosphoproteomix were 81.15 and 48.98 percent of crude protein, respectively; while this value was 13.10 percent in corn-steep liquor. Gas production throughout the incubation and potential of gas production were affected by the experimental treatments, so that the highest values were related to the control treatment (corn-steep liquor). All ruminal-fermentation parameters were affected by the experimental treatments, so that the lowest metabilizable energy (ME) and short chain fatty acids (SCFA) and the highest efficiency of microbial protein synthesis (EMPS) and pH belonged to phosphoprotanomix; the lowest amount of in vitro organic matter apparent digestibility (IVOMAD) and microbial protein synthesis (MPS) were related to protonomix; while the highest amount of in vitro truly degraded dry matter (IVTDDM) and ammonia nitrogen (N-NH3) and the lowest value of partitioning factor (PF) belonged to the control treatment.