Growth performance
Compared with the diet without EGF supplementation, supplied with EGF in the diet increased the ADFI (P < 0.05). The IBW, FBW, ADG, and FCR were not affected by EGF supplementation in the diet (P > 0.05). Injected with LPS decreased the ADG and increased the FCR compared with the treatment without LPS injection (P < 0.05). The IBW, FBW, and ADFI were not affected by whether injected with LPS (P > 0.05). The present study revealed a significantly interaction between EGF and LPS treatment regarding the ADFI (P < 0.05), while there was no significant interaction regarding other growth performance indexes (P > 0.05). The lowest ADFI was observed in the control group, which was significantly lower than the other groups (P < 0.05), while there were no significant differences among the EGF, LPS and EGF + LPS groups (P > 0.05). Besides, there were no significant differences among all groups for the IBW, FBW, ADG and FCR (P > 0.05) (Table 4).
Nutrient apparent digestibility
The results of apparent nutrient digestibility are shown in Table 5. Injected with LPS decreased the apparent digestibility of the crude fat compared with the treatment without LPS injection (P < 0.05). The apparent digestibility of crude protein, crude fiber, gross energy, and P were not affected by whether injected with LPS (P > 0.05). All the indexes of apparent digestibility were not affected by EGF treatment in the diet (P > 0.05). There were no interactions between EGF and LPS treatment regarding all the indexes of apparent digestibility (P > 0.05). The lowest apparent digestibility of crude fat was observed in the LPS group, which was significantly differed from the other groups (P < 0.05), while there were no significant differences among the control, EGF and EGF + LPS groups (P > 0.05). Besides, there were no significant differences among all groups for the apparent digestibility of crude protein, crude fiber, gross energy, and P (P > 0.05).
Concentration of essential microelements in the gastrointestinal tract chyme and feces
The essential microelement concentration in the gastrointestinal tract chyme and feces are shown in Table 6. Compared with the diet without EGF supplementation, supplied with EGF in the diet decreased the Cu concentration in the jejunum and ileum chyme, and feces (P < 0.05). The Cu concentration in the stomach chyme was not affected by EGF supplementation in the diet (P > 0.05). Injected with LPS decreased the Cu concentration in the ileum chyme and increased the Cu concentration in the jejunum chyme compared with the treatment without LPS injection (P < 0.05). The Cu concentration in the stomach chyme and feces were not affected by whether injected with LPS (P > 0.05). The present study revealed a significantly interaction between the EGF and LPS treatment regarding the Cu concentration in the stomach, jejunum and ileum chyme (P < 0.05), and there was no interaction in the feces (P > 0.05). The LPS group had a significantly greater Cu concentration compared with the other groups in the jejunum chyme (P < 0.05), while there were no significant differences among the control, EGF, and EGF + LPS groups (P > 0.05). The control and LPS groups had significantly greater Cu concentration compared with the EGF and EGF + LPS groups in the ileum chyme (P < 0.05), and EGF group had a significantly greater Cu concentration compared with the EGF + LPS group (P < 0.05), while there was no significant difference between the control and LPS groups (P > 0.05). There were no significant differences among all groups for the Cu concentration in the stomach chyme and feces (P > 0.05).
Compared with the diet without EGF supplementation, supplied with EGF in the diet decreased the Fe concentration in the ileum chyme, and feces (P < 0.05). The Fe concentration in the stomach and jejunum chyme were not affected by EGF supplementation (P > 0.05). Injected with LPS decreased the Fe concentration in the ileum chyme and increased the Fe concentration in the jejunum chyme and feces compared with the treatment without LPS injection (P < 0.05). The Fe concentration in the stomach chyme was not affected by whether injected with LPS (P > 0.05). The present study revealed a significantly interaction between EGF and LPS treatment regarding the Fe concentration in the feces (P < 0.05), and there were no interactions in the stomach, jejunum and ileum chyme (P > 0.05). In the jejunum chyme, the LPS group had a significantly greater Fe concentration compared with the control and EGF groups (P < 0.05), and the EGF + LPS group had a significantly greater Fe concentration compared with the control group (P < 0.05), while there were no significant differences between the control and EGF groups, or the LPS and EGF + LPS groups, or the EGF and EGF + LPS groups (P > 0.05). In the ileum chyme, there were no significant differences between the control and LPS groups for Fe concentration (P > 0.05), but these two groups had significantly greater Fe concentration compared with the EGF and EGF + LPS groups (P < 0.05), and the EGF group had a significantly greater Fe concentration compared with the EGF + LPS group (P < 0.05). In the feces, the LPS group had a significantly greater Fe concentration compared with the other groups (P < 0.05), and the control group had a significantly greater Fe concentration compared with the EGF and EGF + LPS groups (P < 0.05), while there were no significant differences between the EGF and EGF + LPS groups (P > 0.05). There were no significant differences among all groups for the Fe concentration in the stomach chyme (P > 0.05).
Compared with the diet without EGF supplementation, supplied with EGF in the diet decreased the Zn concentration in the jejunum and ileum chyme, and feces (P < 0.05). The Zn concentration in the stomach chyme was not affected by EGF supplementation (P > 0.05). Injected with LPS increased the Zn concentration in the jejunum and ileum chyme, and feces compared with the treatment without LPS injection (P < 0.05). The Zn concentration in the stomach chyme was not affected by whether injected with LPS (P > 0.05). The present study revealed significantly interaction between EGF and LPS treatment regarding the Zn concentration in the stomach and ileum chyme, and feces (P < 0.05), and there was no significant interaction in the jejunum chyme (P > 0.05). A significantly greater and lowest Zn concentration was respectively observed in the LPS and EGF groups in the ileum chyme, which significantly differed from the other groups (P< 0.05), and the control group had a significantly greater Zn concentration compared with the EGF + LPS group (P < 0.05). In the feces, the LPS group had a significantly greater Zn concentration compared with the other groups (P < 0.05), and the control group had a significantly greater Zn concentration compared with the EGF group (P < 0.05), while there was no significant difference between the control and EGF + LPS groups, or the EGF and EGF + LPS groups (P > 0.05).
Compared with the diet without EGF supplementation, supplied with EGF in the diet decreased the Mn concentration in the jejunum and ileum chyme, and feces (P < 0.05). The Mn concentration in the stomach chyme was not affected by EGF supplementation (P > 0.05). Injected with LPS increased the Mn concentration in the stomach chyme, and feces compared with the treatment without LPS injection (P < 0.05). The Mn concentration in the jejunum and ileum chyme were not affected by whether injected with LPS (P > 0.05). There were no interactions between EGF and LPS treatment regarding the Mn concentration in the stomach, jejunum and ileum chyme, and feces (P > 0.05). In the stomach chyme, the LPS and EGF + LPS groups had significantly greater Mn concentration compared with the other groups (P < 0.05), while there were no significant differences between the control and EGF groups, or the LPS and EGF + LPS groups (P > 0.05). In the jejunum chyme, the control and LPS groups had significantly greater Mn concentration compared with the other groups (P < 0.05), while there were no significant differences between the control and LPS groups, or the EGF and EGF + LPS groups (P > 0.05). For the ileum chyme, the control and LPS groups had significantly greater Mn concentration compared with the other groups (P < 0.05), and EGF + LPS group had a significantly greater Mn concentration compared with the EGF group (P < 0.05), while there was no significant difference between the control and LPS groups (P > 0.05). In the feces, the LPS group had a significantly greater Mn concentration compared with the other groups (P < 0.05), and the control group had a significantly greater Mn concentration compared with the EGF and EGF + LPS groups (P < 0.05), while there was no significant difference between the EGF and EGF + LPS groups (P > 0.05).
Expression of essential microelement transport-relative genes in the mucosa of the gastrointestinal tract
The expression levels of Zn transport-related genes in the mucosa from the gastrointestinal tract are shown in Fig. 1A-D and Table 7. Compared with the diet without EGF supplementation, supplied with EGF in the diet significantly increased the expression level of Zip4 in the stomach, jejunum and ileum, and significantly increased the expression level of ZnT1 in the stomach (P < 0.05). Injected with LPS significantly decreased the expression levels of Zip4 and Zip7 in the stomach and ileum, and significantly increased the expression level of ZnT1 in the stomach compared with the treatment without LPS injection (P < 0.05). The present study revealed significantly interaction between EGF and LPS treatment regarding the expression level of Zip4 in the stomach, and the expression level of Zip7 in the stomach, jejunum and ileum (P < 0.05) (Table 7).
The EGF and control groups had significantly greater and lowest expression levels of Zip4 in the stomach compared with the other groups, respectively (P < 0.05), and the EGF + LPS group had a significantly greater expression level compared with the control and LPS groups (P < 0.05). The EGF and EGF + LPS groups had significantly greater expression levels of Zip4 in the jejunum compared with the LPS group (P < 0.05), whereas there were no significant differences among the control, EGF and EGF + LPS groups or between the control and LPS groups (P > 0.05). The EGF group had a significantly greater expression level of Zip4 in the ileum compared with the other groups (P < 0.05), while the control and EGF + LPS groups had significantly greater expression levels compared with the LPS groups (P < 0.05), whereas there was no significant difference between the control and EGF + LPS groups (P > 0.05) (Fig. 1A). The control group had a significantly greater expression level of Zip7 in the stomach compared with the LPS and EGF + LPS groups (P < 0.05), and the EGF group had a significantly greater expression level compared with the LPS group (P < 0.05), while there was no significant difference between the control and EGF groups, or between the EGF and EGF + LPS groups, or between the LPS and EGF + LPS groups (P > 0.05). The LPS group had a significantly greater expression level of Zip7 in the jejunum compared with the EGF + LPS group (P < 0.05), while there were no significant differences among the control, EGF and LPS groups, or among the control, EGF and EGF + LPS groups (P > 0.05). The control group had a significantly greater expression level of Zip7 in the ileum compared with the other groups (P < 0.05), and the EGF group had a significantly greater expression level compared with the LPS group (P < 0.05), while there was no significant difference between the EGF and EGF + LPS groups, or between the LPS and EGF + LPS groups (P > 0.05) (Fig. 1B). The greatest expression level of ZnT1 in the stomach was observed in the EGF + LPS group, which significantly differed from the other groups (P < 0.05), and the EGF group had a significantly greater expression level compared with the control and LPS groups (P < 0.05), while there was no significant difference between the control and LPS groups (P > 0.05). The ZnT4 expression level was not obviously changed in any of the samples (P > 0.05) (Fig. 1C-D).
The expression levels of the Cu transport-related genes in the mucosa from the gastrointestinal tract are shown in Fig. 1E-J and Table 7. Compared with the diet without EGF supplementation, supplied with EGF in the diet significantly increased the expression levels of Ctrl and CCS in the stomach and jejunum, and significantly increased the expression level of Cox17 in the stomach and duodenum, and significantly increased the expression level of Atox1 in the stomach, jejunum and ileum, and significantly increased the expression levels of ATP7A and ATP7B in the stomach, duodenum and jejunum (P < 0.05). Compared with the treatment without LPS injection, injected with LPS significantly decreased the expression level of Ctrl in the jejunum, and significantly decreased the expression level of Cox17 in the duodenum and ileum, and significantly decreased the expression level of Atox1 in the stomach and jejunum, and significantly decreased the expression level of ATP7A in the duodenum, and significantly decreased the expression level of ATP7B in the stomach, duodenum and ileum, and significantly decreased the expression level of CCS in the duodenum, jejunum and ileum (P < 0.05). The present study revealed significantly interaction between EGF and LPS treatment regarding the expression levels of Cox17 and ATP7B in the stomach and duodenum, and the expression level of Atox1 in the stomach, duodenum and ileum, and the expression level of ATP7A in the stomach, and the expression level of CCS in the jejunum (P < 0.05) (Table 7).
The LPS group had a significantly lowest expression level of Ctrl in the jejunum compared with the other groups (P < 0.05), while there were no significant differences among the control, EGF and EGF + LPS groups (P > 0.05). (Fig. 1E). In the stomach, the EGF group had a significantly greater expression level of Cox17 compared with the other groups (P < 0.05), and the EGF + LPS group had a significantly greater expression level compared with the control and LPS groups (P < 0.05), but there were no significant differences among the control and LPS groups (P > 0.05). In the duodenum, the LPS group had a significantly lowest expression level of Cox17 compared with the other groups (P < 0.05), whereas there were no significant differences among the control, EGF and EGF + LPS groups (P > 0.05). In the ileum, the control and EGF groups had significantly greater expression levels of Cox17 compared with the other groups (P < 0.05), but there was no significant difference between the control and EGF groups, or between the LPS and EGF + LPS groups (P > 0.05) (Fig. 1F). The EGF group had a significantly greater expression level of Atox1 in the stomach compared with the other groups (P < 0.05), and the control group had a significantly greater expression level compared with the LPS and EGF + LPS groups (P < 0.05), while there was no significant difference between the LPS and EGF + LPS groups (P > 0.05). The EGF group had a significantly greater expression level of Atox1 in the jejunum compared with the other groups (P < 0.05), while the EGF and EGF + LPS groups had significantly greater expression levels compared with the LPS group (P < 0.05), but there was no significant difference between the control and EGF + LPS groups (P > 0.05). The EGF and EGF + LPS groups had significantly greater expression levels of Atox1 in the ileum compared with the other groups (P < 0.05), and the control group had a significantly greater expression level compared with the LPS group (P < 0.05), while there was no significant difference between the EGF and EGF + LPS groups (P > 0.05) (Fig. 1G). The EGF and EGF + LPS groups had significantly greater expression levels of ATP7A in the stomach compared with the other groups (P < 0.05), and the control group had a significantly greater expression level compared with the LPS group (P < 0.05), while there were no significant differences between the EGF and EGF + LPS groups (P > 0.05). The control and EGF groups had significantly greater expression levels of ATP7A in the duodenum compared with the LPS group (P < 0.05), while there were no significant differences among the control, EGF and EGF + LPS groups, or between the LPS and EGF + LPS groups (P > 0.05). The EGF and EGF + LPS groups had significantly greater expression levels of ATP7A in jejunum compared with the other groups (P < 0.05), while there was no significant difference between the EGF and EGF + LPS groups, or between the control and LPS groups (P > 0.05) (Fig. 1H). In the stomach, the EGF group had a significantly greater expression level of ATP7B compared with the other groups (P < 0.05), and the LPS group had a significantly greater expression level compared with the control and EGF + LPS groups (P < 0.05), while there was no significant difference between the control and EGF + LPS groups (P > 0.05). In the duodenum, the EGF group had a significantly greater expression level of ATP7B compared with the other groups (P < 0.05), while there were no significant differences among the control, LPS and EGF + LPS groups (P > 0.05). In the jejunum, the EGF and EGF + LPS groups had significantly greater expression levels of ATP7B compared with the control and LPS groups (P < 0.05), while there was no significant difference between the control and LPS groups, or between the EGF and EGF + LPS groups (P > 0.05). In the ileum, the greatest expression level of ATP7B was observed in the control and EGF groups, which significantly differed from the other groups (P < 0.05), but there was no significant difference between the control and EGF groups, or between the LPS and EGF + LPS groups (P > 0.05) (Fig. 1I). The greatest expression level of CCS in the stomach and jejunum was observed in the EGF group, which significantly differed from the other groups (P < 0.05), and the EGF + LPS group had a significantly greater expression level compared with control and LPS groups (P < 0.05), but there were no significant differences among the control and LPS groups (P > 0.05). In the ileum, the greatest expression level of CCS was observed in the control and EGF groups, which significantly differed from the other groups (P < 0.05), but there was no significant difference between the control and EGF groups, or between the LPS and EGF + LPS groups (P > 0.05) (Fig. 1J).
The expression level of the DMT1 gene, which is revolved in the transport of Mn, Fe, Zn, and Cu in the mucosa of the gastrointestinal tract, is shown in Fig. 1K and Table 7. Compared with the diet without EGF supplementation, supplied with EGF in the diet increased the expression level of DMT1 in the stomach, duodenum and jejunum (P < 0.05). Injected with LPS decreased the expression level of DMT1 in the duodenum, jejunum and ileum compared with the treatment without LPS injection (P < 0.05). The present study revealed significantly interaction between EGF and LPS treatment regarding the expression level of DMT1 in the duodenum and ileum (P < 0.05) (Table 7).
In the stomach, the EGF and EGF + LPS groups had significantly greater expression levels of DMT1 compared with the control and LPS groups (P < 0.05), while there was no significant difference between the control and LPS groups or the EGF and EGF + LPS groups (P > 0.05). In the duodenum, the greatest expression level of DMT1 was observed in the EGF group, which significantly differed from the other groups (P < 0.05), and the control group had a significantly greater expression level of DMT1 compared with the LPS and EGF + LPS groups (P < 0.05), while there was no significant difference between the LPS and EGF + LPS groups (P > 0.05). In the jejunum, the EGF group had a significantly greater expression level of DMT1 compared with the other groups (P < 0.05), and the control group had a significantly greater expression level compared with the LPS group (P < 0.05), but there was no significant difference between the control and EGF + LPS groups, or between the LPS and EGF + LPS groups (P > 0.05). In the ileum, the LPS group had a significantly lowest expression level of CYTB compared with the other groups (P < 0.05), but there were no significant differences among the control, EGF, and EGF + LPS groups (P > 0.05) (Fig. 1K).
The expression levels of Fe transport-related genes in the mucosa of the gastrointestinal tract are shown in the Fig. 1L-N and the Table 7. Compared with the diet without EGF supplementation, supplied with EGF in the diet significantly increased the expression level of CYTB in the stomach, duodenum and ileum, and significantly increased the expression level of Hp in the stomach, jejunum and ileum, and significantly increased the expression level of Tf in the stomach (P < 0.05). Injected with LPS significantly decreased the expression levels of CYTB in the jejunum, and significantly decreased the expression level of Tf in the stomach, duodenum and jejunum compared with the treatment without LPS injection (P < 0.05). The present study revealed significantly interaction between EGF and LPS treatment regarding the expression level of CYTB in the stomach and duodenum, and the expression level of Hp in the ileum (P < 0.05) (Table 7).
In the stomach, the EGF group had a significantly greater expression level of CYTB compared with the other groups (P < 0.05), and the LPS and EGF + LPS groups had significantly greater expression levels compared with the control group (P < 0.05), but there was no significant difference between the LPS and EGF + LPS groups (P > 0.05). The greatest expression level of CYTB in the duodenum was observed in the EGF + LPS group, which significantly differed from the control and LPS groups (P < 0.05), but there were no significant differences among the control, EGF and LPS groups, or between the EGF and EGF + LPS groups (P > 0.05). In the jejunum, the control and EGF groups had significantly greater expression levels of CYTB compared with the other groups (P < 0.05), but there was no significant difference between the control and EGF groups, or the LPS and EGF + LPS groups (P > 0.05) (Fig. 1L). In the stomach, the greatest expression level of Hp was observed in the EGF + LPS group, which significantly differed from the other groups (P < 0.05), and the EGF group had a significantly greater expression level compared with the control and LPS groups (P < 0.05), while there was no significant difference between the control and LPS groups (P > 0.05). In the jejunum, the EGF and EGF + LPS groups had significantly greater expression levels of Hp compared with the control group (P < 0.05), whereas there were no significant differences between the control and LPS groups, or among the EGF, LPS and EGF + LPS groups (P > 0.05). In the ileum, the EGF + LPS group had a significantly greater expression level of Hp compared with the control and LPS groups (P < 0.05), and the control and EGF groups had significantly greater expression levels compared with the LPS group (P < 0.05), whereas there was no significant difference between the control and EGF groups, or between the EGF and EGF + LPS groups (P > 0.05). (Fig. 1M). In the stomach, the EGF group had a significantly greater expression level of Tf compared with the other groups (P < 0.05), and the EGF + LPS group had a significantly greater expression level compared with the control and LPS groups (P < 0.05), while there was no significant difference between the control and LPS groups (P > 0.05). In the duodenum, the control and EGF groups had significantly greater expression levels of Tf compared with the other groups (P < 0.05), while there was no significant difference between the control and EGF groups, or between the LPS and EGF + LPS groups (P > 0.05). In the jejunum, the EGF group had a significantly greater expression level of Tf compared with the EGF + LPS group (P < 0.05), while there were no significant differences among the control, EGF and LPS groups, or among the control, LPS and EGF + LPS groups (P > 0.05) (Fig. 1N).