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.