Effect of tannin levels and pH on in vitro dry matter degradability and ammonia production from oil seed cake-acacia catechu leaves pellets in cattle inoculums

In present study pellets of oil seed cake (groundnut cake-GNC, cotton seed cake-CSC, mustard seed cake-MSC, linseed cake-LSC and soybean cake-SBC) and Acacia catechu leaves-ACL (tannin source) with different tannin levels (2–8%) and different pH levels were evaluated for in vitro dry matter degradability (IVDMD) and ammonia production in cattle inoculums. IVDMD of pellets was significantly lower (P<0.05) at 2, 4, 6 and 8% tannin levels than control. However, IVDMD at 2% tannin level (54.37%) was more (P<0.05) than at 4, 6 and 8% tannin levels (46.09–48.91%). Highest reduction in IVDMD of pellets was observed for GNC (from 86.68 to 39.48%) and lowest for LSC (from 68.15 to 50.89%) with the addition of tannins. Mean pellets IVDMD was significantly (P<0.05) influenced by pH levels and was highest at pH 7 (with 0% tannin 70.50%) and lowest at pH 4 (47.98%). Reduction in pellet IVDMD due to pH was highest from GNC (from 86.68 to 48.89%) and lowest from LSC (from 68.15 to 53.44%). Ammonia production from pellets was significantly higher (P<0.05) at 0% tannin level (control) than that of 2, 4, 6 and 8% tannin levels. Tannin reduced mean NH₃ production maximum from SBC pellets (63.17 to 28.47 mg/100 ml) and lowest from CSC (15.60 to 5.80 mg/100 ml). Ammonia production from pellets was more at pH 8 (23.81) than that of pH2 and pH4 (18.02 and 17.00 mg/100 ml), respectively. Results of the in vitro study revealed that all tannin levels reduced pellets IVDMD and NH₃ production.