author(s)
Arulkumar S, SK Saha, Manojkumar M, Dinesh S, Saravanakumar M and Arivazhagan M

abstract
In the present experiment four unconventional oil cakes (UOC) viz. karanj (Pongamia glabra), mahua (Madhuca indica), neem (Azadirachta indica) and castor bean (Ricinus communis) were tested for their effect on methane production, total gas production, IVTD, and ammonia nitrogen concentration. In Experiment I all the UOCs (Karanj, Mahua, Neem and castor bean) were evaluated for their feed fermentation in in vitro where 70% of UOCs and 30% maize was used as a substrate (50:50 Concentrate : Wheat straw). The methane production (ml/g DM) was significantly reduced (p<0.01) by 48.48, 45.02, 37.06 and 33.19 percent in karanj cake, mahua cake, neem cake and castor bean meal, respectively as compared to control. The IVTD (%) in karanj and mahua cake inclusion was found comparable with control unlike in neem and castor bean meal inclusion where the IVTD was significantly lower in comparison to control. Based on the first experiment, karanj and mahua cake was selected for further in vitro experiment for selecting the ratios of the UOC. The karanj and mahua cake were selected and tested in in vitro at different combinations viz. 25:75, 50:50 and 75:25 ratios. The total gas production in karanj and mahua cake (75:25) inclusion was comparable as compared to control. The methane production (ml/g DM) was significantly lower (p<0.01) in karanj and mahua cake mixture (75:25) inclusion as compared to control group. The IVTD (%) in karanj and mahua cake mixture at 75:25 inclusion was comparable with control, unlike other combinations.