A study was carried out to evaluate the effect of dietary probiotic supplementation and stocking density on the performance, relative carcass yield, gut microflora, and stress markers of broilers. One-day-old Ross 308 male broiler chickens (n = 480) were allocated to 4 experimental groups for 42 d. Each treatment had 8 replicates of 15 chicks each. Two groups were subjected to a high stocking density (HSD) of 20 birds/m² and the other 2 groups were kept at low stocking density (LSD) of 10 birds/m². A basal diet supplemented with probiotic 1 and 0.5 g/kg of diet (in starter and finisher diets, respectively) was fed to 2 treatments, one with HSD and the other with LSD, thereby making a 2 × 2 factorial arrangement. There was no interaction between stocking density (LSD and HSD) and dietary probiotic (supplemented and unsupplemented) for all the variables. Feed intake and weight gain were significantly low and feed conversion ratio was poor in broilers at HSD. Dietary probiotic significantly enhanced the feed intake and weight gain in starter phase only. Dietary probiotic supplementation had no effect (P > 0.05) on total aerobs, Salmonella sp., and Lactobacilli populations in the intestines of broilers. However, HSD reduced the Lactobacilli population only (P < 0.05). Relative breast yields were significantly higher in broilers reared at LSD than HSD. Thigh meat yield was higher in broilers in HSD group compared to LSD. Dietary probiotic did not affect the relative carcass yield and weight of lymphoid organs. Serum malondialdehyde, corticosterone, nitric oxide, and plasma heterophil:lymphocyte ratio were not affected either by stocking density or dietary probiotic supplementation. In conclusion, HSD negatively affected the performance and intestinal Lactobacilli population of broilers only, whereas probiotic supplementation enhanced the performance of broilers during the starter phase only. Total aerobes, Salmonella, Lactobacilli carcass yield, and stress indicators of broilers were not affected by the dietary supplementation of probiotic under the conditions of the present study.

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The effect of sodium butyrate on various bodily parameters of broilers such as performance, gut microflora, gut morphology, and immunity is reviewed in order to highlight its importance as an alternative to antibiotic growth promoters. Sodium butyrate is used as a source of butyric acid, which is known for its beneficial effects in the gut in monogastrics. Sodium butyrate is available in uncoated and entericcoated forms protected with fat or fatty acid salts. Varying results in productive performance, gut microbes, and gut morphology have been reported in the literature in response to supplementation of broiler diets with uncoated and fatcoated types of sodium butyrate. However, sodium butyrate has shown pronounced effects on immunity of chickens that are not fully understood yet. Although there are contrasting results of sodium butyrate in chicken, further research is needed using the sodium butyrate coated with the salts of fatty acids.

The present study was conducted to investigate the influence of different levels of dietary phytogenic feed additive (PFA) on growth performance, caecal microbiota, and intestinal morphology of broilers. A total of 480 Ross-308 one-day-old male broilers chicks (body weight 43+3 g) were randomly assigned to 32 replicate pens of four experimental groups, each experimental group consisting of 8 replicates (each replicate pen consisting of 15 chicks). A basal diet was formulated based on corn and soybean meal that was fed to the control group. Other dietary treatments received a commercial PFA at 100 mg/kg (PFA100), 125 mg/kg (PFA125), and 150 mg/kg (PFA150). Body weight gain, feed intake, and feed conversion rate of broilers were recorded on 1-21, 22-42, and 1-42 days of age. One bird was slaughtered on the 21 st and 42 nd days and caecal contents were aseptically collected. Jejunal tissue samples were also collected on the same days. Total aerobic bacteria, coliforms, Escherichia coli, and lactobacilli were counted in the caecal contents. Villus height, villus diameter, crypt depth, muscular thickness, and goblet cell number per villus were recorded. There was no difference among the dietary treatments for growth performance and caecal microbe populations at any phase. However, the dietary PFA supplementation increased the villus height, villus width, muscularis thickness, and reduced the crypt depth and goblet cell number per villus in broilers compared to those fed control diets. In conclusion, this study suggests that dietary supplementation of a PFA consisting of blend of different spices and essential oils did not improve growth performance and caecal microbial populations despite a positive improvement in the jejunal morphometry of broilers.