Different levels of single-strain probiotic (Bacillus subtilis) with proteolytic enzyme (serratiopeptidase) can be used as an alternative to antibiotic growth promoters in broiler oleh Muhammad Mushtaq, Baseerat Ali, Majid Ali, Neelam BiBi, Rabin Raut, Gamaleldin M. Suliman, Ayman A. Swelum