EffECTS Of' ANTIBIOTIC AND PROBIOTIC ON THE PElWORMANCE OF BROILER CHICKS FED OPTIMAL AND SUB - OPTIMAL PROTEIN LEVELS

Abstract

An experiment was conducted during the period from January to

February, 1997 to study and compare the effectiveness of two levels of

• the antibiotic "Virginiamycin" with the probiotic "Lato-Sacc" as growth promoters on growth performance, carcass yield and composition as well as the economical efficiency of unsexed 5-d old Arbor-Acres broiler strain fed com-soya diets containing two levels of protein.

• The experimental work of the present study was carried out at El- Takamoly poultry project, Fayoum Governorate, Egypt.

A total number of 600 unsexed 5-d old Arbor-Acres broiler strain chicks were equally divided into I 0 groups of 6 replicates each. Four basal diets were formulated to contain 21% & 19% CP nearly isocaloric (2900 kcal./kg diet) for starter period (5-26 d) and 18 & 16% CP nearly isocaloric (3000 kcal./kg diet) for finisher period (27-53 d). Each of the four basal diets was either unsupplemented or supplemented with two levels of YM (10 and 20 ppm) and LS (0.5 and 1.0 kg/ton diet) plus control diet. Therefore, ten experimental starter and finisher diets were • t&sted. At the start of finishing period, each chick group was equally subdivided into 2 sub-groups ( fed either 16 or 18% CP diets.) of 3 replicates each. Therefore, twenty experimental groups were used in the finishing period. The following criteria were measured or calculated:-

Body weight (BW), body weight gain (BWG), feed intake (Fl), feed conversion (FC), crude protein conversion (CPC), caloric efficiency ratio (CER) grovvth rate (GR), performance index (PI), mor1ality rate (MR) and economical efficiency (E.Ef. ).