Comparative nutritional evaluation of raw and detoxified karanj (Pongamia glabra) cake by in vitro gas production technique

Abstract

Karanj (Pongamia glabra) cake is an important proteinaceous feeding resource for livestock available as by-product from biodiesel industry. However, its use in livestock feeding is restricted due to the presence of toxic principles. A suitable method of detoxification of karanj cake was evolved which resulted into substantial removal of major toxins viz., karanjin, pongamol and trypsin inhibitors while preserving its nutrients. Further, both raw and detoxified karanj cake were subjected to in vitro study by incorporation at 0 (control), 12.5, 25.0, 37.5, 50.0, 62.5, 75.0, 87.5 and 100 percent levels by replacing soybean meal in the concentrate mixtures (22% CP) on protein equivalent basis. Concentrate mixtures and fine ground wheat straw (1:1 on weight basis) was used as substrate for in vitro study. The substrate degradation in terms of gas volume produced in 24 h (ml/200 mg), truly degradable organic matter in rumen (TDOMR; mg/200 mg), TDOMR%, partitioning factor, microbial biomass production (MBP; mg/200 mg) and efficiency of microbial biomass production (MBP/100 mg TDOMR) were found to be comparable (P > 0.05) for both raw and detoxified karanj cake. It may be concluded that complete replacement of soybean meal with either raw or detoxified karanj cake in vitro did not exert any adverse effect on substrate degradation and efficiency of microbial biomass production.