Effects of encapsulated cinnamaldehyde on growth performance, intestinal digestive and absorptive functions, meat quality and gut microbiota in broiler chickens

Essential oils are potential antimicrobial alternatives and their applications in animal feeds are limited due to their fast absorption in the upper gastrointestinal tract. This study investigated the effects of encapsulated cinnamaldehyde (CIN) at 50 mg/kg or 100 mg/kg on the growth performance, organ weights, meat quality, intestinal morphology, jejunal gene expression, nutrient digestibility, and ileal and cecal microbiota. A total of 320 male day-old broiler Cobb-500 chicks were randomly allocated to four treatments with eight pens per treatment (10 birds per pen): 1) basal diet (negative control, NC); 2) basal diet supplemented with 30 mg/kg avilamycin premix (positive control, PC); 3) basal diet with 50 mg/kg encapsulated CIN (EOL); 4) basal diet with 100 mg/kg encapsulated CIN (EOH). Despite birds fed EOH tended to increase (P = 0.05) meat pH at 24 h, all pH values were normal. Similar to PC group, meats from birds fed EOL and EOH showed a reduced (P < 0.05) Warner–Bratzler force shear (WBFS) compared to the NC group. The highest villus to crypt ratios (VH/CD; P < 0.05) were observed in broilers fed either EOL or EOH, with an average of 14.67% and 15.13% in the duodenum and 15.13% and 13.58% in the jejunum, respectively. For jejunal gene expressions, only six out of the 11 studied genes showed statistically significant differences among the dietary treatments. Gene expressions of cationic amino acid transporter 1 (CAT-1) and neutral amino acid transporter 1 (B(0)AT-1) were upregulated in EOH-fed birds compared to PC and NC-fed birds (P < 0.05), respectively; while the expression of proliferating cell nuclear antigen (PCNA) was downregulated in EOL-fed birds when compared to NC birds (P < 0.05). Nonetheless, the expressions of cadherin 1 (CDH-1), zonula occludens 1 (ZO-1), and maltase-glucoamylase (MG) were all upregulated (P < 0.05) in EOH-fed birds compared to PC-fed birds. The apparent ileal digestibility (AID) of dry matter, crude protein, crude fat and of all 18 tested amino acids increased in EOL-fed birds (P < 0.01). Additionally, relative abundances (%) of ileal Proteobacteria decreased, while ileal and cecal Lactobacillus increased in EOH-fed birds (P < 0.05). In conclusion, dietary encapsulated CIN improved meat quality and gut health by reducing meat WBFS, increasing VH/CD in intestines, jejunal gene expressions, AID of nutrients and beneficial ileal and cecal microbiota composition.