Treating canola meal changes in situ degradation, nutrient apparent digestibility, and protein fractions in sheep

The present study was conducted to evaluate the effects of three different treatment methods of canola meal (CM) on ruminal degradability of crude protein (CP) and dry matter (DM) in situ and apparent digestibility of nutrients in sheep. The fractionation of protein for treated CM was measured as well. Treatments were: T0 = CM with no treatment (control); T1 = treatment with formaldehyde; T2 = treatment with acetic acid; and T3 = heating treatment. The ruminal degradability of CP and DM was measured using four rumen fistulated Mehraban sheep. For digestibility trial twelve intact Mehraban sheep were used. The results showed that neutral detergent insoluble nitrogen (NDIN) contents were 5.28%, 5.29%, 6.25% and 5.16% and acid detergent insoluble nitrogen (ADIN) contents were 4.46%, 4.59%, 4.44% and 4.50% for T0, T1, T2 and T3, respectively (P > 0.05). Considering nitrogen fractions, A+ B1 and B2 showed differences among treatments (P < 0.05) with B3 and C being similar among treatments. The degradability kinetic parameters for DM (a, b and c) differed among treatments (P < 0.05). The lowest effective degradability of DM was for control treatment. The parameters a, b and c for CP degradability also were affected by treatments (P < 0.05). Ruminal degradation rates of DM and CP were decreased and the highest degradability for both DM and CP was observed in untreated CM. The digestibility of DM and OM showed no difference among treatments; however, CP digestibility was different among treatments (P < 0.05). Regardless of CM treatment method, treated CM had greater B2 and lower A+ B1 fractions compared with untreated CM and solubility of protein in CM decreased with different treatments. The results of the present study suggest that untreated CM has the greatest degradation rate in rumen and treating CM considerably decreased the solubility of protein and ruminal degradation rate. In conclusion the results suggest the treatment CM with formaldehyde to increase apparent digestibility of protein and the treatment CM with acetic acid to decrease ruminal degradation rate of protein.