PERKEMBANGAN MIKROBIA USUS AYAM BROILER YANG DIBERI PAKAN STEPDOWN PROTEIN DENGAN PENAMBAHAN ASAM SITRAT SEBAGAI ACIDIFIER

Abstract

The aim of the this study was to evaluate the effectiveness of the addition of citric acid (CA) as acidifiers in dietary protein stepdown of starter and finisher periods of broiler on the development of lactic acid bacteria (LAB) and Escherichia coli (E. coli). Dietary treatment was initiated when the broiler was 8-day-old with initial body weight of 186.23 ±0.68 g. Feed was composed of corn, rice bran, fish meal, soybean meal, vegetable oil, CaCO3, citric acid (CA), both synthetic citric acid (SCA) and lime citric acid (LCA). Protein and metabolizable energy contents of stater feed was 21.4% and 2856.9 kcal/kg, respectively for normal level, and 19.2% and 2884.1 kcal/kg, recpectively for protein stepdown. Protein and metabolizable energy contents of finisher normal feed was similar to those of dietary protein stepdown for starter, while those of dietary protein stepdown of finisher feed was 17.3% and 2882.1 kcal/kg, respectively. A total of 168 birds of broiler were allocated into 7 treatments and 4 replicates (birds each) based on a completely randomized design arrangement.Dietary treatments applied were T0 (normal without stepdown and CA), T1 (stepdown without CA), T2 (stepdown + 0.8% LCA), T3 (stepdown + 0.4% SCA), T4 (stepdown + 0.8% SCA), T5 (stepdown + 1.2% SCA) and T6 (stepdown + 1.6% SCA). Parameters observed were potential hydrogen (pH) of digesta, and populations of LAB and E. coli. The results showed that feeding protein stepdown with the addition of CA as acidifiers significantly (p<0.05) decreased pH and the amount of E. coli and increased the number of LAB. In conclusion, SCA addition at the level of 0.8% as acidifiers in dietary protein stepdown effectively decreases pH and the amount of E. coli and,on the other hand, increases the population of LAB.