This study aimed to investigate the efficacy of probiotic supplementation in mitigating stress and improving performance, carcass yield, carcass quality parameters, sensory acceptability, microbiological quality and economic profitability of broilers reared at different stocking densities. Two hundred and forty chicks were divided into four groups; two groups were reared at a low stocking density (LSD, 10 bird/m2), including one group that was provided with Protexin® probiotic (Enterococcus faecium) supplemented in water (LSDP). Similarly, the other two groups were reared at a high stocking density (HSD, 15 bird/m2), including one group that was provided with the same probiotic supplementation (HSDP). Throughout the growing cycle, bird performance was monitored. At the end of the growing cycle, stress indicators were measured in blood. Besides, carcass and giblet weights, dressing yield, carcass quality parameters, sensory acceptability, microbiological quality and economic profitability were assessed. As a result, HSD mostly impaired broiler performance, increased stress indicators, reduced carcass yields, carcass quality parameters and sensory acceptability, while boosted profitability and slightly lowered microbiological quality. On the other hand, probiotic supplementation reversed the negative effects of HSD. As probiotic supplementation boosted broiler performance, reduced blood stress indicators, increased carcass and giblet yields, carcass quality parameters and sensory scores, besides, it improved the microbiological status of broiler meat in terms of fecal coliforms and E. coli MPN. To conclude, rearing broilers at high stocking density induced stress, compromised performance and reduced carcass quality. These negative impacts could be successfully faced by using probiotic supplementation in drinking water.

Objectives: The research was carried out on broilers to determine the efficacy of probiotics (Bacillus subtilis and Saccharomyces boulardii combined) supplementation on growth performances, nutrient retention (metabolizable energy, dry matter, and crude protein), and cecal microbiology (Bifidobacteria spp., Clostridium spp., and coliforms). Materials and Methods: A total of 160 broiler chicks (day-old) were selected and differentiated randomly into 4 groups (T0, T1, T2, and T3) (40 × 4) comprising 40 birds in every single group. The control group (T0) was fed commercial broiler feed only and the other three groups, referred to as treatment groups (T1, T2, and T3), were treated with 1 gm ciprofloxacin, 1 gm probiotic, and 1 gm probiotic plus 0.5 gm enzyme, respectively, in per liter of fresh dietary water 8 h daily for 7 days in each phase. Experimental trials were divided into 2 phases, the starter phase from day 0 to 21 and the finisher phase from day 22 to 35. Results: Bodyweight gain and nutrient retention in experimental broiler birds in treatment groups were significantly (p < 0.05) higher than the control group. Overall body weight gain and nutrient retention of broiler chicks in treatment groups T2 and T3 were better than T1. From day 22 to 35, cecal Clostridium and coliform bacterial load counts were significantly lower p < 0.01, p < 0.05, and p < 0.01, respectively, in T1, T2, and T3 treatments than T0. Overall, Clostridium and coliform bacterial counts in the birds of treatment group T2 were significantly lower (p < 0.05) than T0. Conclusion: The probiotics, in addition to enzyme supplementation, had suitable influence effects on growth performance of broilers, birds retention of nutrient, and microfloral count in birds cecum. [J Adv Vet Anim Res 2021; 8(4.000): 534-539]