Abstract:
This experiment was conducted to evaluate the response of broiler chicks to diet containing various levels of dietary bacterial probiotic (BP) as natural growth promoter alternative to antibiotic. Experiment parameters covered growth performance, slaughter, carcass values, commercial cuts and giblets percentage, subjective meat quality, carcass dressing percentage and economical appraisal were calculated. The experimental design used was complete randomize design (CRD). A total of 200, five days old 125 gm. initial weight, un sexed Arbor Acres strain broiler chicks were used in this experiment. The chicks were divided into five experimental groups with five replicates, each of eight chicks (5x5x8). The first group (A) fed on basal dietwithout feed additives as negative control diet (NC), the second group (B), fed on basal diet with antibiotic (Neomycin 20 mg /kg ) as positive control (PC), the other groups C, D, and E were fed on basal diet supplemented with bacterial probiotic (BP) at levels 1, 2, and 3 gm/kg respectively. The basal diet was formulated to meet the nutrients requirements of broilers according to (NRC, 1994). Experimental diets were fed for five weeks.
The results showed that, the addition of dietary (BP) at all inclusion levels improved significantly (P<0.05) the value of body weight gain (BWG) andfeed conversion ratio (FCR) compared to (NC) without any effect on feed intake of broiler chicks. No mortalities were recorded throughout the experimental period. The results indicated that, the carcass dressing percentage were increased significantly (p<0.05) in birds fed on 2 and 3 gm/kg dietary (BP) compared to those fed on (NC) diet .Whereas, the differences were not significant (p>0.05) among the other treatment groups. No significant differences (p>0.05) were observed among all treatment groups in the percent of giblets (gizzard, liver, and heart), and the subjective meat quality values (color, juiciness, tenderness, and flavor) of broiler chicks. The results showed that, all levels of (BP) added to the broiler diets wereimproved significantly (p<0.05) commercial cuts (breast, thigh and drumstick) and their percentage of separable tissue compared to (NC).
The results of economical evaluation of experimental diets, showed that the addition of (BP) at various levels to the broiler diets caused more net profit compared to (NC), but the value of profitability ratio (1.23) of group E (3 gm/kg dietary BP) was the highest of the tested groups .
According to the results of this study, dietary (BP) appeared to be superior compared to antibiotic. It thus shows that dietary (BP) can be used asreplacement for antibiotic in broiler diets.
