Comparison of Energy Estimates of Mixed Diets Obtained from RIVGPT and in-vivo Digestibility Trials in Lactating Cows

Abstract

To compare the energy estimates of mixed diets obtained from rumen in vitro incubation for gas production (RIVIGP) and digestion trial (DT) in lactating cows, six cows in mid lactation were divided in to three groups of two each. Three mixed diets were prepared by using finger millet straw (FMS) and concentrate supplements (CS) in the ratio of 41:59 (Diet-1&3) and 43:57 (Diet-2). These diets were tested in three periods in a switch over design. Each period lasted for four weeks with an adjustment period of three weeks and digestion trial for one week. The metabolisable energy (ME, MJ kg-1 DM) content of FMS was 6.6 and CS ranged from 10.5 to 11.4. The ME content of mixed diets at maintenance level of intake obtained by DT for diets-1,2 and 3 were 9.3, 9.7 and 9.5 MJ/kg DM respectively. The corresponding ME values obtained from RIVIGP were 8.9, 9.3 and 9.4 respectively. The mean ME output (Maintenance + 4%FCM yield + weight gain) for the diets-1,2 and 3 were 104.9, 112.3 and 106.9 MJ/d respectively. The ME intake estimated from ME obtained from DT and RIVIGP for the diets-1,2 and 3 were 107.7 and 111.9; 116.6 and 116.9; 103.1 and 110.2 respectively. Hence, the observed performance of growing ram lambs expressed in terms of the total ME output was accountable to the extent of 99.5 and 95.4% of ME intake estimates obtained from ME values derived by DT and RIVIGP respectively.