Rujie Liu

This study aimed to comprehensively investigate the impact of soybean β-conglycinin on broiler growth performance, nutrient utilization, allergic and inflammatory responses, intestinal barrier integrity, and cecal microbiota. A total of 168 newly hatched (1-day-old) Arbor Acres broilers with similar body weights were randomly divided into 6 treatment groups with 4 replicates of 7 broilers per replicate: the control group received a soybean-free basal diet, while the remaining five experimental groups were provided with diets supplemented with purified soybean β-conglycinin at the doses of 1%, 2%, 3%, 4%, and 5%. The results demonstrated that dietary 1–5% β-conglycinin supplementation significantly reduced the growth performance, nutrient utilization, and content of digestive enzymes in broilers (p < 0.05). Dietary 1–5% β-conglycinin supplementation also significantly increased the serum levels of histamine, β-conglycinin-specific IgY and IgM, TNF-α, and IL-6 and decreased IL-10 levels; the 3% group had the highest levels of histamine, TNF-α, and IL-6 and the lowest levels of IL-10 (p < 0.05). β-conglycinin supplementation significantly down-regulated the mRNA expression of tight junction proteins, MUC2 and IL-10, and up-regulated the expression of TNF-α and IL-6 in the small intestinal mucosa (p < 0.05). Furthermore, the Shannon and Simpson indices were significantly reduced by dietary 1–5% β-conglycinin administration (p < 0.05). The relative abundance of beneficial bacteria (Blautia, Lactobacillus, and Butyricoccus) was significantly decreased in all treatments (p < 0.05). Taken together, these findings suggest that β-conglycinin induces allergic and inflammatory responses, impairs intestinal barrier integrity, and alters the intestinal microbial balance, ultimately leading to reduced nutrient utilization and inhibited growth in broilers. Notably, our study demonstrated that dietary supplementation with 1% β-conglycinin already had various negative effects on broilers, and particularly supplemental 3% β-conglycinin induced serious allergic and inflammatory reactions. Therefore, in the present study, it is recommended that the inclusion level of β-conglycinin in broiler formula feed should not exceed 1%, i.e., the β-conglycinin content in the diet should not exceed 0.6% (converted from β-conglycinin purification purity).

In this study, three samples were randomly selected from corn, wheat, and broken rice before and after extrusion for electron microscope scanning, Fourier transform infrared spectral analysis, and in vitro digestion to investigate the impact of extrusion on physicochemical characteristics and starch digestion kinetics of cereals. The cereals used for extrusion were sourced identically before and after the process, with each analysis conducted in triplicate. The results showed that the extrusion compromised the physical structure of cereal, resulting in loose structure arrangement, and the ratio of Fourier transform infrared spectral absorbance at wavelength 1047 cm⁻¹ and 1022 cm⁻¹, which characterized the short-range order of starch, was significantly reduced (p < 0.05). In addition, the proportion of rapidly digestible starch (RDS), the velocity parameter k of digestive kinetics and the predicted glycemic index of cereals were significantly increased by extrusion (p < 0.05). Digestibility kinetics showed a total increase of 10.7%, 7.3%, and 5.4% for cereals, along with a sharp rise in digestion rate within the first 15 minutes. The findings revealed that the compromising of starch’s structural integrity and the increase in proportion of RDS not only enhanced overall starch digestibility, but also significantly accelerated its digestion, particularly during the initial 15 min of intestinal digestion.