The effect of three probiotic dietary supplements on the laying and reproductive performance of layer hens and broiler breeder hens was investigated. A total of four hundred and eighty, 22-week-old layer hens were given diets containing one of three probiotics (1 g/kg diet for each probiotics) from weeks 22 to 49. Seven hundred and twenty female and sixty-four male broiler breeders were also subjected to the same additive feeding procedure between 21 and 50 weeks of age. The layer hen and breeder trials were initiated simultaneously and performed in pens located in the same area. Either egg production rate or egg weight was affected by the microbial cultures administered. Body weight and mortality were not affected. Egg production rate, egg weight and egg mass benefited from some of the probiotics, while, overall, the probiotics led to significant improvements in the feed conversion rate of layer hens. All of the probiotic preparations decreased the cracked-to-broken egg ratio, compared to the untreated control group. One of the three probiotic supplements significantly improved the egg production rate and increased the settable egg and chick yield per hen in broiler breeders, whereas, overall, probiotics tended to decrease settable egg weight. Probiotics enhanced hatchability, but no beneficial effects were observed on fertility. Based on these findings, it can be said that the microbial cultures in the probiotic preparations exhibited host-specific and strain-specific differences in their activities as performance-enhancer feed additives, with improvements in some selected performance parameters.