Effect of in ovo injection of raffinose on growth performance and gut health parameters of broiler chicken

Abstract

The effects of in ovo injection of raffinose (RFO) as a prebiotic on growth performance, relative weight of proventriculus, gizzard, drumstick and breast muscles, and ileum mucosa morphology were examined in Cobb 500 broilers. A total of 240 fertilized eggs were divided into 4 groups: a non-injected with intact shell and 3 levels of RFO solution (1.5, 3.0, and 4.5 mg in 0.2 mL of an aqueous diluents). The RFO solution was injected into the air sac on d 12 of incubation. In total 144 birds were fed a standard diet and management and sacrificed at d 21 post hatch for collection of samples. Total RNA was extracted from the small intestine, and RT-qPCR was performed to quantify mRNA levels of marker genes of immune cells. Injection of RFO had no significant effect (P > 0.05) on d one body weight of chicks. On d 21, the relative weight of the proventriculus, drumstick, breast, and gizzard was not affected (P > 0.05) by RFO. On hatch d, the villus height increased linearly (P < 0.01) with an increasing dose of RFO. Also, an increasing dose of RFO increased the villus height and villus height:crypt depth ratio (P < 0.05) but did not affect the crypt depth on d 21. The expression levels of CD3 and chB6, which are T cell and B cell marker genes, respectively, were significantly enhanced by high dose RFO (4.5 mg). In conclusion, although an increasing dose of RFO in ovo injection did not significantly influence growth performance or slaughter yield of broilers, RFO has the potential of enhancing ileum mucosa morphology and improving immunity in the small intestine, which are indicators of improved gut health.

Keywords: growth performance; ileum mucosa morphology; immunology; in ovo injection; prebiotic.

Figure 1.

Effects of RFO in ovo injection on ileum mucosa morphology of chickens at 21 d of hatch. Each character on the figure means the following treatments: A: Non-injected, B: 1.5 mg RFO, C: 3.0 mg RFO, D: 4.5 mg RFO. Typical images of ileum mucosa morphology are shown. Images were captured with light microscopy at 50 × magnification. Scale bar indicates 500 μm.

Figure 2.

Effects of RFO injection on immunity of small intestine of broilers. Total RNA was extracted from the small intestine of broilers at 21 d of age. The expression of each gene was examined using RT-qPCR and expressed as ratio to GAPDH, with the level being set to 1 in broilers treated without RFO in each gene. A: Effect of RFO injection on marker genes of adaptive immune cells. B: Effect of RFO injection on innate immune cells and cytokines. Data shown are the mean ± SE (n = 6). # indicates P = 0.051 and * indicates P < 0.05. Statistical analysis was conducted in comparison to non-injected. RFO = raffinose (mg/0.2 mL).