Effect of varying levels of formaldehyde treatment of mustard oil cake on rumen fermentation, digestibility in wheat straw based total mixed diets in vitro

AIM: The aim of the current study was to protect the protein in mustard cake by different levels of formaldehyde treatment with a view to optimize the level of formaldehyde. MATERIALS AND METHODS: Different levels of formaldehyde treatment (0, 1, 1.5 and 2% of crude protein) containing concentrate and roughages diet in 40:60 ratio were tested for their effect on nutrients digestibility, in vitro ammonia release, in vitro gas production and change in protein fractions. Non-significant (p≤0.05) effect on pH, microbial biomass, partitioning factor, total gas production (TGP), TGP per g dry matter and TGP per g digestible dry matter (ml/g) was observed in almost all the treatments. RESULTS: Total volatile fatty acids at 2% formaldehyde treatment level of mustard cake was lower (p<0.05) as compared to other groups, while in vitro dry matter digestibility and in vitro organic matter digestibility were reported to be low in 1% formaldehyde treated group. CONCLUSION: On a holistic view, it could be considered that formaldehyde treatment at 1.5% level was optimal for protection of mustard oil cake protein.