In Vitro Degradation and Rumen Fermentation Characteristics of Soybean Meal Protected with Different Levels of Formaldehyde

Abstract

The objective of this study was to determine thein vitro degradation and rumen fermentation characteristics of soybean meal that were protected with different levels of formaldehyde. In a completely randomized design experiment, 4 levels of formaldehyde (0, 0.6, 0.8, 1.0, and 1.2%; volume/weight) were applied on soybean meal. Protected soybean meals were incubated for 48 h using a 2-stage in vitro technique. The results showed that protecting soybean meal with formaldehyde decreased the dry matter and organic matter digestibilities (P<0.05) with the lowest on 0.8 to 1.2% formaldehyde treatments. Although there was no significant effects on rumen culture pH, total and proportion of VFA, a significant decrease in NH₃-N concentration and slightly decrease of microbial protein concentration were noticed due to formaldehyde treatments (P<0.05). Low NH₃-N and microbial protein concentrations was detected on 0.8, 1.0, and 1.2% formaldehyde treatments 16.3, 15.0, and 10.5 mg/100 mL, respectively, for NH₃-N and 8.32, 7.05, and 6.35 mg/mL, respectively, for microbial protein. It can be concluded that protecting soybean meal with formaldehyde can decrease rumen degradation and NH₃-N concentration with the cost of microbial protein synthesis. The best concentration of formaldehyde for protecting soybean meal was at 0.8%.