Two experimental trials on commercial broiler (Ross-308) were conducted to evaluate the
carryover effects of artificial insemination (AI) in parent flock (PF) kept in cages (C), and on floor (F) in comparison to natural mating (NM) in floored PF. A total of 900 broiler chicks were obtained from 38-week-old PF (peak production), representing C, F, and NM evenly during first trial, whereas in second trial, similar number of broiler chicks were obtained from same PF during post peak phase (55 week of age). Subsequent effects of AI and NM in PF were evaluated by bacteriology, post hatch mortality, growth performance, immune response, and carcass traits on experimental birds. Chicks being produced through NM exhibited significantly (P ≤ 0.05) improved growth performance i.e., feed conversion ratio, weight gain, European efficiency factor along with the least (P ≤ 0.05) post hatch mortality and prevalence of Escherichia coli (E.coli), Salmonella Pullorum (SP), and Mycoplasma gallisepticum (MG) tested on 0,15 and 30th days of age . Moreover, the experimental chicks obtained from floored PF subjected to AI particularly during post peak phase expressed the highest (P ≤ 0.05) contamination of the said pathogens along with post hatch mortality. Perhaps, immune response against New Castle disease and infectious bronchitis vaccines and slaughtering parameters remained nonsignificant (P > 0.05) among the 3 treatments under both trials. Thus, it is concluded that the best growth performance along with the least depletion and microbial load of concerned pathogens were being pertained by the experimental broiler birds representing NM.