Effects of Supplementation with Encapsulated Different Postbiotics, Alone or with Inulin, on Growth Performance, Carcass and Organ Characteristics, Blood Parameters, Growth Hormone, and Insulin-like Growth Factor mRNA in Broilers

This study aimed to evaluate the effects of encapsulated postbiotics derived from various probiotic microorganisms, alone or in combination with inulin, on the growth performance, carcass traits, organ weights, blood parameters, and mRNA expression of selected hormones in broilers. A total of 588 one-day-old male Ross-308 chicks were randomly designated to six replicates of seven dietary treatments (initial body weight: 40.85 ± 0.56 g, per replicate, n = 14 chicks). The treatments consisted of a basal diet (C), supplemented with encapsulated postbiotics (0.30%) derived from <i>Lactobacillus plantarum</i> (ELP), <i>Bacillus subtilis</i> (EBS), or <i>Enterococcus faecium</i> (EEF), as well as combinations of these encapsulated postbiotics with 1.0% inulin (ELPI, EBSI, and EEFI) for six weeks. The results demonstrated that the body weight and body weight gain of birds that were fed diets supplemented with encapsulated postbiotics or their combinations with inulin significantly increased in comparison to the C group (<i>p</i> < 0.001). Feed intake (FI) remained unaffected during days 1–21, as did feed conversion ratios (FCR) during days 22–42, and days 1–42 demonstrated no significant differences (<i>p</i> > 0.05). However, FCR improved during days 1–21, and FI increased during days 22–42 and 1–42 (<i>p</i> < 0.05). Carcass yield, including breast, thigh, and abdominal fat yields, was enhanced (<i>p</i> < 0.001). Although the relative weights of the heart, spleen, pancreas, and liver were unaffected (<i>p</i> > 0.05), the relative weight of the bursa of Fabricius increased (<i>p</i> < 0.001). Serum antioxidant status and immunoglobulin A and M levels were higher, while liver enzymes, cholesterol, triglycerides, and total oxidant status were lower in the supplemented groups compared to the control group (<i>p</i> < 0.001). Serum glucose and protein levels remained unchanged (<i>p</i> > 0.05). The mRNA expression of growth hormone and insulin-like growth factor was upregulated in the supplemented groups (<i>p</i> < 0.001). In conclusion, encapsulated postbiotics (0.30%) derived from different probiotics, alone or combined with inulin (1.0%), positively influenced growth performance, carcass traits, and immunity in male broilers.