THE EFFECT OF DIETARY PROTEIN CONCENTRATION ON NUTRIENT UTILIZATION OF RHODE ISLAND RED CHICKEN IN WOLAITA (SOUTHERN ETHIOPIA)

Abstract

The effect of dietary crude protein (CP) concentration on feed intake, nutrient retention and efficiency of utilization of growing Rhode Island Red (RIR) chicks fed for a period of 12 weeks from 9 to 93 days of age was assessed and CP requirement determined in Wolaita, southern Ethiopia. Diets were formulated at 14% (T1), 16 % (T2), 18 % (T3), 20 % (T4) and 22 % (T5) CP levels out of maize, wheat bran, soybean, sunflower cake, noug cake, limestone, salt, rear-premix, methionine and lysine. Ten chicks were randomly distributed to each of four replicates of the five treatment diets. Chicks were fed in group and feed intake determined daily. Body weight was measured weekly. At the beginning of trial, ten chicks whose average weight was closest to weight of chicks in experimental groups were killed and put in a deep freezer at -20oC. At the end of the experiment, from randomly selected 3 replicates per treatment, 3 male and 3 female (1 male & 1 female per replicate) chicks were selected, fasted for 12 hrs, killed and put in a deep freezer at -20oC. Dry matter intake (DMI) of chicks fed diets with different levels of CP was not significantly (p>0.05) different. T3 had the highest (p<0.05) and T2 the lowest (p<0.05) intake values of most of the nutrients. Chicks in T1 showed significantly (p<0.05) lower protein retention than chicks fed on T3 whereas chicks fed on T2, T4 and T5 fall in between. Chicks fed different levels of dietary CP were not significantly (p>0.05) different in energy, calcium and phosphorus retention. Chicks fed on T4 and T5 were significantly (p<0.05) lower in efficiency of utilization of protein (EUP) than T2 whereas chicks fed on T1 and T3 fall in between. Chicks fed on T2 had the highest but chicks fed on T5 the lowest EUP. Chicks fed different levels of dietary CP were not significantly (p>0.05) different in efficiency of energy and phosphorus utilization. Lower (P<0.05) efficiency of utilization of calcium was obtained from chicks fed on T1 than on T4 whereas chicks fed on T2, T3 and T5 fall in between. Mortality of 2.5% and 12.5% of chicks was encountered only in T1 and T5, respectively. Optimum efficiency of nutrient utilization and retention were obtained at 16% dietary CP level and could be recommended as CP requirement of RIR chicks up to the age of 13 weeks. Intakes of energy (572 kJ/head), DM, Ca and P (40, 0.38 and 0.21 g/head, respectively) at 16% dietary CP level could also be recommended as daily allowances.