Nutrient intake and digestibility of cotton gin trash treated with hypochlorite oxidant or extruded

Bernard, J.K., Woldeghebriel, A. and Mueller, T.C. 2001. Nutrient intake and digestibility of cotton gin trash treated with hypochlorite oxidant or extruded. J. Appl. Anim. Res., 19: 165-176. To determine the effect of hypochlorite oxidant and extrusion on nutrient intake and digestibility of gin trash (GT) and compare GT with pelleted cottonseed hull (PCSH), two trials were conducted. Treatments included PCSH, untreated (CONT), predigested with a hypochlorite oxidant (PD), extruded (EXT) and predigested and extruded (P&E) byproduct. Five Holst.ein heifers were used in a 5 x 5 Latin square design and fed diets containing 25% GT or PCSH. Dry matter (DM) intake of heifers was not different among treatments but intake of diets containing GT was 17% lower than PCSH. Apparent digestibility of DM, OM, and NDF was similar for all treatments; however, ADF digestibility was lowest for PCSH compared to CONT, PD and P&E. Ruminal NH3-N concentration was highest for P&E compared to PCSH, CONT and PD, Extrusion decreased molar proportions of acetate (A) and increased propionate (P) resulting in lower A:P ratios. Molar proportions of butyrate was greatest for CONT and P&E and molar proportions of isovalerate was greatest for PCSH and PD. Concentrations of plasma urea-N (PUN) and glucose were not different among treatments. In situ digestibility of DM and NDF was greatest for GT compared to PCSH. Treatment of GT with the mixed oxidant or extruding the GT did not improve DM or NDF digestibility at 48 and 96 h compared to CONT. All GT treatments were digested equally at 192h. Extrusion improved bulk density of GT by 63% but did not improve DM intake or apparent digestibility. Extruding the material treated with the mixed oxidant in the current study appeared to eliminate any potential increase in apparent digestibility compared with the PD byproduct. This may in part be attributed to the potential loss of solublized components resulting in increased concentration of less digestible fraction in the remaining material.