The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36–72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

Banning antibiotic growth promoters has negatively impacted poultry production and sustainability, which led to exploring efficient alternatives such as probiotics, probiotics, and synbiotics. Effect of in ovo injection of Bacillus subtilis, raffinose, and their synbiotics on growth performance, cecal microbial population and volatile fatty acid concentration, ileal histomorphology, and ileal gene expression was investigated in broilers (Gallus gallus) raised for 21 days. On 300 h of incubation, a total of 1,500 embryonated eggs were equally allotted into 10 groups. The first was non-injected (NC) and the remaining in ovo injected with sterile distilled water (PC), B. subtilis 4 × 105 and 4 × 106 CFU (BS1 and BS2), Raffinose 2 and 3 mg (R1 and R2), B. subtilis 4 × 105 CFU + raffinose 2 mg (BS1R1), B. subtilis 4 × 105 CFU + raffinose 3 mg (BS1R2), B. subtilis 4 × 106 CFU + raffinose 2 mg (BS2R1), and B. subtilis 4 × 106 CFU + raffinose 3 mg (BS2R2). At hatch, 60 chicks from each group were randomly chosen, divided into groups of 6 replicates (10 birds/replicate), and fed with a corn–soybean-based diet. In ovo inoculation of B. subtilis and raffinose alone or combinations significantly improved body weight, feed intake, and feed conversion ratio of 21-day-old broilers compared to NC. Cecal concentrations of butyric, pentanoic, propionic, and isobutyric acids were significantly elevated in R1, R2, BS2R1, and BS2R2, whereas isovaleric and acetic acids were significantly increased in R1 and BS2R1 compared to NC. Cecal microbial population was significantly altered in treated groups. Ileal villus height was increased (p < 0.001) in BS1, R2, and BS2R2 compared to NC. The mRNA expression of mucin-2 was upregulated (p < 0.05) in synbiotic groups except for BS1R1. Vascular endothelial growth factor (VEGF) expression was increased (p < 0.05) in BS2, R1, BS1R1, and BS1R2 compared to NC. SGLT-1 expression was upregulated (p < 0.05) in all treated birds except those of R1 group compared to NC. The mRNA expressions of interleukin (IL)-2 and toll-like receptor (TLR)-4 were downregulated (p < 0.05) in BS2 and R1 for IL-2 and BS1R1 and BS2R2 for TLR-4. It was concluded that in ovo B. subtilis, raffinose, and synbiotics positively affected growth performance, cecal microbiota, gut health, immune responses, and thus the sustainability of production in 21-day-old broilers.

Objective: An experiment was conducted to investigate the continuous and intermittent lighting program effects on terms of the productive performance, carcass traits, blood biochemical parameters, innate immune and oxidative status in broiler chicks. Methods: A total of 600 Cobb-500 one day old chicks were randomly allocated into six equal groups (100 chicks per treated group with five replicates of 20 chicks each) based on lighting program; 22 continuous lighting (22 C), 11 h lighting + 1 darkness twice daily (11 L /1 D), 20 h continuous lighting (20 C), 5 h lighting + 1 darkness four times daily (5 L/1 D), 18 h continuous lighting (18 C) and the final group subjected for 3 h lighting + 1 h darkness six times daily (3 L/1 D). The experimental period lasted 42 days. Results: Compared with those under the intermittent light program, broiler chicks exposed to continuous lighting for 22 h had significant improvement in live body weight and carcass (dressing and breast percentage) measured traits. Though reducing lighting hours significantly reduced feed intake and feed conversion ratio values. Different lighting programs revealed no significant effect on all blood biochemical parameters. Oxidative stress and innate immunity parameters significantly enhance by reducing lighting hours (3L/1D). Conclusion: The findings suggest that reducing lighting hours up to 3L/1D would be more useful in enhancing feed efficiency, innate immunity, and oxidative status compared with continuous lighting programs on broilers.

Length of production cycle and broiler marketing decision is an important issue especially when productivity and product quality are considered. The objectives of this study were to determine the effects of the age at marketing on productive performance, carcass characteristics and meat quality traits of broiler chickens at five different ages. For this purpose, a total of 450 mixed-sex Cobb 500 broiler chicks were used. Chicks were randomly distributed into five equal groups with 3 replicates allocated in 15 pens. Broilers were reared until different marketing ages at 30, 35, 40, 45 and 50 days. Productive traits were recorded and performance indexes were calculated at different marketing ages. At each marketing day, a slaughter test was done using 12 birds subjected to a simplified carcass analysis. Breast muscles were used for evaluated meat quality and physicochemical properties. The results indicated that the age at marketing had significant effects (p<0.05) on all parameters investigated in point of productive traits, performance indexes, carcass traits, cut-up pieces and meat quality of broiler chickens. In conclusion, delaying marketing age positively increased live body weight and yield of live mass. But it negatively reduces feed efficiency, feed conversion ratio and livability % with increasing age which negatively affected the EPEF of broiler production. According to the EPEF, which expresses technical efficiency in one index, it can be stated that broiler production is only profitable with an EPEF at 30 th and 35 th days of age only. Thus, broiler farmers and producers have to differentiate or balance between ignoring some reduction in productive performance and compensating this with some added value from selling chicken in portions. But actually further research is required to find out an optimal marketing age in terms of economic considerations to calculate the costs and profits at different marketing ages.

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