Effect of graded levels of concentrate and nitrogen replacement on dry matter digestibility of untreated and alkaline hydrogen peroxide treated mustard (Brassica campestris) straw in vitro Misra A.K.*, Mishra A.S., Tripathi M.K., Prasad R., Jakhmola R.C. Division of Animal Nutrition, Central Sheep and Wool Research Institute, Avikanagar - 304 501, India *Reprint request: Dr. A.K. Mishra, Tel.: +91-1437-28143; Fax: +91-1437-28163. E-mail: asim@cswri.raj.nic.in
Abstract In vitro dry matter digestibility (IVDMD) of untreated (UMS) and alkaline hydrogen peroxide (1.0% NaOH+1.5% H2O2; w/w) treated mustard straw (AHPMS) was assessed at various inclusion levels of concentrate (0, 20, 30, 40 and 50 per cent of substrate on DM basis), replacing 0, 14, 28, 42 and 100 per cent CP or equivalent nitrogen (N) content of the substrate through urea. Substrate having various combinations of concentrate (5 levels) and N replacement (5 levels) with UMS and AHPMS (2 straw type) were incubated for 48 h in an in vitro fermentation system. Effect of all the three factors (straw type, levels of concentrate, levels of N replacement) on IVDMD of UMS and AHPMS were significant (P<0.01). The AHP treatment of mustard straw (MS) improved IVDMD of MS by four units. A significant (P< 0.01) linear correlation (r2=0.81) was observed with IVDMD and the levels of concentrate additions in the substrate incubated with UMS or AHPMS. Within the straw type, the response of AHPMS was higher (P<0.05) to every incremental level of concentrate inclusion in the substrate. The N replacement levels and IVDMD of UMS and AHPMS was negatively correlated (r2= −0.79). Whereas, the IVDMD of straw portion of UMS and AHPMS showed a different pattern and it was higher at 20 to 30 per cent concentrate inclusion with 14 to 28 percent N replacement levels respectively in UMS and AHPMS. There was no associated effect of concentrate levels vs N replacement levels, straw type vs N replacement levels and concentrate level vs N replacement levels vs straw type. It is concluded that a mustard straw (untreated or treated) based diet containing 20–30 per cent concentrate mixture is suitable to support optimum rumen fermentation in vitro. The urea can be used to replace 14 to 28 per cent dietary nitrogen without any adverse effect on in vitro fermentation of mustard straw based diets. The study suggests that a mustard straw based complete diet can be formulated with 20 to 30 per cent concentrate and 0.59 to 1.18 per cent urea in total diet. Top Key words Mustard straw, Urea, Concentrate, Nitrogen, In vitro, Dry matter digestibility. Top |