Effect of Various Levels of Exogenous Fibrolytic Enzymes and Fumaric Acid on the Digestibility, Methane Emission and Performance of Growing Sahiwal Calves

This study was aimed to test whether combination of exogenous fibrolytic enzymes and fumarate as fumaric acid, a hydrogen sink may result in any complementary effects in vivo. Growing Sahiwal calves (18; 6–12 month-old; average body weight, 132 kg; range 79–192 kg) were arranged into 3 groups in a randomized complete block design. Treatments were: Control (no additives), T1 (control + 0.75 g/kg DM of EFE + Fumaric acid (FA) @ 2% of DM and T2 (control + 1.5 g/kg DM of EFE + FA @ 2% of DM). Exogenous fibrolytic enzymes (EFE) (cellulase with activity >4500 – 5000 µM glucose/g/min and Xylanase with activity >7500 – 8000 µM xylose/g/min, mixed in 50:50 w/w). During growth trial of 120 days, calves were fed with a basal diet containing sorghum stover, green grass (freshly cut) and concentrate mixture (50: 10: 40) ad lib. (15% in excess of the previous day’s intake). Various levels or doses of EFE in combination with FA had no effect on final body weight, average daily gain and daily feed intake. There was no effectofsupplementationofadditivesonapparentdigestibilityofDM, OM,CF,EE,NDF,andADFbutCP digestibility increased as a result of T1 treatment. Nitrogen intake and nitrogen retention was similar in three groups. Methane energy estimated as loss of GE intake decreased by 13.54 and 10.76 per cent, for T1 and T2 respectively, compared to the control and methane expressed as g/kg digestible dry matter intake was 12.29% lower on T1 treatment and 5.03 % with T2 compared to the control. These reductions were not reflected in growth performance of calves. It can be concluded that reduction of methane production caused by feed additives to the basal diet in the present study was though quantifiable it could not improve animal performance and nutrients utilization in contrast to the previous in vitro findings observed during the use of EFE and organic acids combination on roughage based diet.