Digestion kinetics of complete diets based on wheat straw and alkali treated cottonseed hulls

Digestion kinetics of isocaloric (55% TDN) complete diets comprising 60% roughage (either wheat straw (WS) or 5% alkali treated cottonseed hulls; CSH, the latter in mash and flaked forms containing 10, 12 and 14% CP, was studied. Potentially degradable DM fraction of CSH based diets, irrespective of CP level, was higher than WS based diets. Potential DM degradation of CSH and WS based diets was similar and flaking of CSH based diets did not reveal any improvement in its potential degradability. Effective DM degradability of CSH based diets did not improve by the alkali treatment alone, however, combined effect of alkali and flaking process improved the effective degradability. Lag time of NDF digestion in CSH based diets was higher (P<0.05) than WS based diets, irrespective of the CP level and physical form. Rate of NDF digestion was maximum for the diets containing 12% CP, irrespective of source of roughage or processing. The CSH based diets containing 12% CP had higher (P<0.05) potential as well as apparent extent of fibre digestion than those containing other CP levels in both mash and flake form. It can be concluded that combined effect of alkali and flaking process improved the effective degradability of CSH but not the potential degradability. The optimum CP level in complete diets containing 60% roughage for maximum utilization of fibre was found to be 12 percent.