Bioavailability of Major Minerals from Commonly Used Ruminants Feeds Using Dialyzability Technique

Four feeds namely maize (Zea mays) grain, deoiled rice (Oryza sativa) bran, groundnut (Arachis hypogaea) cake and mustard (Brassica campestris) cake were used to assess the bioavailability of calcium, phosphorous, magnesium, sodium and potassium by dialyzability technique under in vitro conditions. For this, three Karan Fries calves kept on roughage based diet were used for collection of rumen liquor through stomach tube. In vitro dry matter digestibility (IVDMD) of different samples was estimated at three stages i.e. simulating ruminal, abomasal and intestinal conditions followed by determination of bioavailability of major minerals in the soluble fraction of intestinal stage sample through a 12 kD dialyzable membrane. Maize grain (69.91±1.11) possessed the highest (P<0.05) IVDMD value followed by mustard cake (68.51±1.087), groundnut cake (63.59±2.07) and deoiled rice bran (51.22±1.05) at the intestinal stage of digestion. Similarly, the highest (P<0.05) bioavailability of Ca, P and Mg (71.76±1.66, 87.57±0.37 and 85.05±0.12%, respectively) was found for maize grain followed by mustard cake, groundnut cake and deoiled rice bran, however, Na bioavailability was higher (98.10±0.10%) in case of groundnut cake and numerically similar values were obtained for K. Results suggested that in vitro method could be used for prediction of bioavailable minerals fraction from feeds, however, validation by actual in vivo experiment is required before accepting the bioavailability values while considering these for dietary mineral requirements.