To compare the energy estimates of mixed diets obtained from rumen in vitro incubation for gas production (RIVIGP) and digestion trial (DT) in NariSuwarna X Kenguri F1 sheep, twenty four sheep were divided into six groups of five each. Six mixed diets were prepared by using sugarcane trash and concentrate feed mixture in the ratio of T-1 80:20, T-2 70:30, T-3 60:40, T-4 50:50, T-5 40:60 and T-6 30:70. The feeding trial was carried out for the duration of six weeks with an adjustment period of five weeks and collection period of one week. The metabolisable energy (ME, MJ kg-1 DM) content of diets at maintenance level of intake obtained by DT for diets-1, 2, 3, 4, 5 and 6 were 6.7, 6.9, 7.4, 7.2, 7.8 and 9.4 respectively. The corresponding ME values obtained from RIVIGP were 5.3, 5.9, 6.2, 7.5, 8.6 and 9.4 respectively. The difference between the ME obtained from DT (digestion trial) and ME predicted from RIVIGPT was found to be 10.7 per cent. The mean ME output (Maintenance + weight gain) for the diets-1, 2, 3, 4, 5 and 6 were 6.37, 6.34, 7.38, 7.70, 8.06 and 8.27 respectively. The ME intake estimated from ME obtained from DT and RIVIGP for the diets-1, 2, 3, 4, 5 and 6 were 4.91 and 3.79, 5.02 and 4.22, 7.63 and 6.46, 7.74 and 8.13, 8.76 and 9.81, 11.42 and 11.85 respectively. Hence, the observed performance of NariSuwarna x Kenguri F1 sheep expressed in terms of the total ME output was accountable to the extent of 97.0 and 99.6% of ME intake estimates obtained from ME values derived by DT and RIVIGP respectively.
RIVIGPT;Digestion Trial;Validation of ME;Sugarcane Trash;Sheep