Abstract
N-carbamylglutamate (NCG) has been shown to enhance performance in neonatal piglets. However, few studies have demonstrated the effect of NCG on the intestinal mucosal barrier. This study was conducted to determine the effects of dietary NCG supplementation on intestinal mucosal immunity in neonatal piglets after an Escherichia coli (E. coli) challenge. New-born piglets (4 d old) were assigned randomly to one of four treatments (n = 7), including (I) sham challenge, (II) sham challenge +50 mg/kg NCG, (III) E. coli challenge, and (IV) E. coli challenge +50 mg/kg NCG. On d 8, pigs in the E. coli challenge groups (III and IV) were orally challenged with 5 mL of E. coli K88 (108 CFU/mL), whereas pigs in the sham challenge groups (I and II) were orally dosed with an equal volume of water. On d 13, all piglets were sacrificed, and samples were collected and examined. The results show that average daily gain in the E. coli challenged piglets (III and IV) was decreased (PE.coli<0.05). However, it tended to be higher in the NCG treated piglets (II and IV). Ileum secretory IgA, as well as IFN-γ, IL-2, IL-4 and IL-10 in ileal homogenates, were increased in E. coli challenged piglets (III and IV). Similarly, ileum SIgA and IL-10 levels, and CD4+ percentage in NCG treated piglets (II and IV) were higher than no-NCG treated piglets (PNCG<0.05). However, the IL-2 level was only decreased in the piglets of E. coli challenge + NCG group (IV) compared with E. coli challenge group (III) (P<0.05). No change in the IL-2 level of the sham challenged piglets (III) was observed. In conclusion, dietary NCG supplementation has some beneficial effects on intestinal mucosal immunity in E. coli challenged piglets, which might be associated with stimulated lymphocyte proliferation and cytokine synthesis. Our findings have an important implication that NCG may be used to reduce diarrhea in neonatal piglets.
Highlights
In modern pig farming, an increase in average litter size may enhance the potential for mortality from starvation and lack of innate immunity [1]
No significant ADG difference was observed in NCG-supplemented groups compared with control diet groups, there was a trend that NCG-supplementation alleviated the weight growth underdevelopment and increased the average daily gain after E. coli challenge (PNCG = 0.08)
Accumulated research has indicated that dietary arginine supplementation can enhance the growth of milk-fed young pigs [18], improve intestinal function [19], decrease expression of inflammatory cytokines, and reduce intestinal mucosal injury in different animal models [8,20,21]
Summary
An increase in average litter size may enhance the potential for mortality from starvation and lack of innate immunity [1]. The development of immune system of neonatal piglets is important. It is often underdeveloped [2]. Immunoglobulin quantitation, including IgA, IgG, and IgM, in the serum of young pigs decreased significantly at 14-d-old [3], and this may be due to an immature immune system, which is a main risk factor for infectious diseases in early life, especially the intestinal mucosal immunity [4]. It is well known that the intestine is the main entry route for foreign antigens, including invading pathogens that often lead to severe diarrhea [5]. A well developed intestinal mucosal immune system can protect the mucous membranes against potentially dangerous microbes and some other toxic elements in the environment [4]. Many attempts to explore strategies to improve intestinal mucosal immunity and to understand the corresponding mechanisms have been made [7,8]
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