Azzawi Dates (Phoenix dactylifera) as a Substitute for Corn as an Energy Source in Sheep Diet: In vitro Gas Production and Fermentation

In vitro gas production technique was used in the current study to evaluate Azzawi date (AD) as a substitute for corn grain (CG). The AD was used to replace corn grain at graded levels in the proportion: 0:100 (CG), 25:75 (AD25), 50:50 (AD50), 75:25 (AD75), and 100:0 (AD100). Gas production (GP) was continuously measured by incubating samples in buffered rumen fluid from cannulated sheep and it was recorded at 3, 6, 9, 12, 24, 48 and 72h of incubation. Cumulative GP, kinetics of GP (a, b and c), ammonia nitrogen (NH₃-N) and volatile fatty acids (VFA) concentrations were determined, while metabolizable energy (ME), net energy (NE), organic matter digestibility (OMD), microbial protein (MP) were estimated. The gas volume was increased (P<0.05) at 12h with increasing the substitution levels of AD in the feed, the values ranged between 31.3 and 44.7 ml/200 mg DM. However, it was found to be decreased (P<0.05) at 48 and 72h with increasing substitution levels of AD. There were no differences in the gas production found at 24h. Data of VFA, NE, OMD and MP were similar (P>0.05) among the feeds. The energy (ME; MJ/kg DM) value of AD25 (10.4) and AD50 (10.3) were comparable to that of CG (10.5); however it was reduced (P<0.05) with AD75 and AD100. Data demonstrated that, Azzawi date at the level of 50 g/100g of substrate (i.e., AD50) may have similar energy contents as of corn grain, and it can be used as a source of energy in ruminant diets either alone or in combination with corn grain.