Effect of Varying Levels of Formaldehyde and Heat Treatment on the Ruminal Degradability of Common Protein Supplements Using Nylon Bag Technique

Three protein supplements viz. mustard cake (MC), deoiled mustard cake (DMC) and soybean meal (SBM) were treated with 40% formaldehyde (FA) at the rate of 0.5 and 1.0% of total crude protein (CP) content and also heat treated (HT) in hot air oven at 140°C for 30 and 60 minutes. The potential degradability ‘b’ of CP was greater (P&0.05) in SBM followed by DMC and MC. The degradation rate ‘c’ of CP was lower (P&0.05) in FA (0.5 and 1.0% level) treated DMC and SBM. HT (30 and 60 min) treatment also significantly (P&0.05) reduced the effective degradability ‘ED’ of CP in DMC and SBM. However, 1.0% FA treatment significantly (P&0.05) reduced the ED of CP in all the three cakes. The potentially degradable fraction ‘b’ was significantly lower (P&0.05) at 1.0% FA treatment. Heat treatment reduced the effective degradability (ED) of DM significantly (P&0.05) as compared to control and the difference between duration of heat treatment was also significant (P&0.05). FA treatment at both levels also reduced (P&0.05) the ED of DM. There was no significant effect of any of the treatments on the soluble fraction ‘a’ of DM. The digestion kinetic parameters of CP revealed that FA and heat treatments did not have any significant effect on ‘a’ and ‘b’ fractions of CP but degradation rate ‘c’ was significantly reduced (P&0.05) by both the treatments of oilcakes, indicating their efficacy in protein protection. The best results were obtained at 1.0% formaldehyde treatment in MC and DMC, and 0.5% for SBM without any adverse effect on protein quality.