Low-Protein Diet Supplemented with Medium-Chain Fatty Acid Glycerides Improves the Growth Performance and Intestinal Function in Post-Weaning Piglets

Abstract

Medium-chain fatty acid glycerides have been shown to provide energy for rapid oxidation in the body. The study was conducted to investigate the effects of dietary supplementation with medium-chain fatty acid glyceride on the growth performance and intestinal health of weaned piglets fed with a low-protein diet. Nighty healthy weaned piglets were randomly divided into five treatments: NP (Normal protein treatment, normal-protein diet no antibiotics included); NC (Negative control, low-protein diet no antibiotics included); PC (Positive control, low-protein diet +75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT (tricaprylin + tricaprin treatment, low-protein diet + tricaprylin + tricaprin); GML (glycerol monolaurate treatment, low-protein diet + glycerol monolaurate). The results showed that the average daily feed intake (ADFI) of the MCT treatment was significantly higher than that of the NP, NC treatments (p < 0.05). In the jejunum, the villus height of the GML treatment was significantly lower than that of the PC treatment (p < 0.05), and the number of goblet cells in the GML treatment was higher than that in the NC treatment (p < 0.05). Compared with the NC treatment, the MCT treatment significantly increased the level of claudin-1, Zonula occludens-1(ZO-1), while the GML treatment significantly increased the level of claudin-1, occludin, ZO-1 (p < 0.05). In the ileum, the level of ZO-1 in the GML treatment was significantly higher than that in the NP, NC, PC treatments (p < 0.05). Compared with the NC treatment, the GML treatment significantly increased the level of Secretory immunoglobulin A (SIgA) in the ileum and serum, while the MCT treatment significantly increased the level of SIgA and decreased the level of interleukin-6 (IL-6) in the ileum (p < 0.05). These results showed that the addition of medium-chain fatty acid glycerides to a low-protein diet could improve the growth performance and intestinal functional barrier of weaned piglets and also improve the immune function of weaned piglets.

Keywords: cytokines; intestinal morphological structure; intestinal permeability; medium-chain fatty acid glycerides; tight junction protein.

Figure 1

The morphology and structure of the jejunum in the piglets. (A): The jejunal villus height. (B): The jejunal crypt depth. (C): The jejunal lymphocyte numbers. (D): The jejunal goblet cell numbers. Values are the mean ± SEM, n = 6 per treatment (the n = 6 refers to the number of pigs slaughtered and sampled). ^a,b Mean values sharing different superscripts within a row differ (p < 0.05). NP = normal protein basal diet no antibiotics included; NC = low-protein basal diet no antibiotics included; PC = low-protein basal diet + antibiotics (75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT = low-protein basal diet + 2 kg/T tricaprylin/tricaprin; GML = low-protein basal diet + 2 kg/T glycerol monolaurate.

Figure 1

The morphology and structure of the jejunum in the piglets. (A): The jejunal villus height. (B): The jejunal crypt depth. (C): The jejunal lymphocyte numbers. (D): The jejunal goblet cell numbers. Values are the mean ± SEM, n = 6 per treatment (the n = 6 refers to the number of pigs slaughtered and sampled). ^a,b Mean values sharing different superscripts within a row differ (p < 0.05). NP = normal protein basal diet no antibiotics included; NC = low-protein basal diet no antibiotics included; PC = low-protein basal diet + antibiotics (75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT = low-protein basal diet + 2 kg/T tricaprylin/tricaprin; GML = low-protein basal diet + 2 kg/T glycerol monolaurate.

Figure 2

The morphology and structure of the ileum in piglets. (A): The jejunal villus height. (B): The jejunal crypt depth. (C): The jejunal lymphocyte numbers. (D): The jejunal goblet cell numbers. Values are the mean ± SEM, n = 6 per treatment (the n = 6 refers to the number of pigs slaughtered and sampled). NP = normal protein basal diet no antibiotics included; NC = low-protein basal diet no antibiotics included; PC = low-protein basal diet + antibiotics (75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT = low-protein basal diet + 2 kg/T tricaprylin/tricaprin; GML = low-protein basal diet + 2 kg/T glycerol monolaurate.

Figure 3

The expressions of tight junction proteins of the jejunum in piglets. (A): The protein expression of claudin-1. (B): The protein expression of occludin. (C): The protein expression of ZO-1. (D): The protein expression of claudin-1, occludin, ZO-1. The (A–C) expressions of tight junction protein and (D) representative immunohistochemical staining images in the jejunum of piglets. Values are the mean ± SEM, n = 4 per treatment (the n = 4 refers to the number of pigs slaughtered and sampled). ^a,b,c,d Mean values sharing different superscripts within a row differ (p < 0.05). NP = normal protein basal diet no antibiotics included; NC = low-protein basal diet no antibiotics included; PC = low-protein basal diet + antibiotics (75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT = low-protein basal diet + 2 kg/T tricaprylin/tricaprin; GML = low-protein basal diet + 2 kg/T glycerol monolaurate.

Figure 4

The expressions of tight junction proteins of the ileum in piglets. (A): The protein expression of claudin-1. (B): The protein expression of occludin. (C): The protein expression of ZO-1. (D): The protein expression of claudin-1, occludin, ZO-1. The (A–C) expressions of tight junction protein and (D) representative immunohistochemical staining images in the ileum of piglets. Values are the mean ± SEM, n = 4 per treatment (the n = 4 refers to the number of pigs slaughtered and sampled). ^a,b,c,d Mean values sharing different superscripts within a row differ (p < 0.05). NP = normal protein basal diet no antibiotics included; NC = low-protein basal diet no antibiotics included; PC = low-protein basal diet + antibiotics (75 mg/kg quinocetone, 20 mg/kg virginiamycin and 50 mg/kg aureomycin); MCT = low-protein basal diet + 2 kg/T tricaprylin/tricaprin; GML = low-protein basal diet + 2 kg/T glycerol monolaurate.