Effects of cassava chip substitution for ground corn in concentrate on rumen ecology and microbial protein synthesis in goat

Abstract

This experiment aimed at studying the effect of levels of cassava chip (CC) substitution for groundcorn on nutrient utilization and rumen ecology in goat. Ten Thai Native x Anglo Nubian 50% crossbred male goats,1.68 + 0.02 years old with average body weight (BW) of 27 + 2 kg were arranged in 5x5 Replicated Latin Squaredesign. The goat were fed with fresh Napier grass (Pennisetum purpureum) ad libitum and were supplemented withconcentrate containing 0, 25, 50, 75 or 100 % cassava chip (CC) substitution for ground corn at 2% of BW as drymatter basis. The results showed that there were no significant differences (P>0.05) among groups regarding totalintake of dry matter, organic matter, neutral detergent fiber and acid detergent fiber. However, when CC levels were100% substitution for ground corn, the total crude protein intake (87.63 g/d) were significantly (P<0.05) lower thanthose of 0, 25 and 50 % CC substitution for ground corn (104.30, 102.75 and 103.85 g/d, respectively). Blood ureanitrogen and glucose concentration, rumenl pH, total volatile fatty acid concentration in rumen fluid, includingacetic acid (C2), propionic acid (C3), butyric acid (C4) and C2 : C3 ratio were not significantly different (P>0.05)among goat fed with diet containing 0, 25, 50, 75 and 100% CC substitution for ground corn. However, mean ofammonia nitrogen concentration in rumen fluid in goat fed with diet containing 100% CC substitution for groundcorn (12.33 mg/dl) were significantly (P<0.05) lower than those of 0 and 25% CC substitution for ground corn(16.18 and 18.83 mg/dl, respectively). Microbial populations including bacteria, protozoa and fungi zoospores inrumen fluid were not significantly difference among the groups. Moreover, no significantly differences (P>0.05) inrumen microbial N were found. Base on this experiment, the optimal level of CC as energy source substitution forground corn in concentrate should be 25-75% with no adverse effect on nutrient utilization and rumen ecology ofThai native x Anglo Nubian 50% crossbred male goat fed with fresh napier grass.