New findings of intestinal alkaline phosphatase: effects on intestinal and organ health of piglets challenged with ETEC F4 (K88)

ABSTRACT The aim of this study was to assess the addition of intestinal alkaline phosphatase (IAP) to diets on the count of bacterial populations, pH of digestive organ contents, histopathological description, proinflammatory markers, hepatic glycogen reserve, and diarrhoea incidence of piglets challenged with Escherichia coli. Sixty-four crossbred piglets (7.16±0.28 kg body weight, 25-days-old) were assigned to four treatments in a completely randomised block design: negative control (NC), NC + antibiotic (ANT), NC + 15 mg IAP, or NC + 30 mg IAP kg−1 of diet, eight replications of two piglets per experimental unit. All piglets were orally challenged with 6 mL of a solution containing enterotoxigenic Escherichia coli K88 at 106 CFU mL−1 at 15 days of experimentation. The study lasted for 19 days. At the end of the experimental period, the piglets were slaughtered (six animals per treatment). Enterobacteriaceae in caecum and colon was lower in piglets on 30 mg IAP than with ANT and NC, ANT or 15 mg IAP, respectively. Enterobacteriaceae adhered to the mesenteric lymph nodes (MLN) was greater in piglets fed ANT than the other treatments. Lactic acid bacteria (LAB) count in caecum was greater in piglets fed NC and ANT. In MLN, LAB count was greater in ANT and 30 mg IAP-fed piglets compared with 15 mg IAP. Piglets in 30 mg IAP in diet showed a tendency for lowering tissue necrosis compared with NC or ANT. Piglets fed 30 mg IAP showed a reduction in diarrhoea incidence in the pre- and post-challenge compared with 15 mg IAP and all other treatments, respectively. Based on the criteria, addition of 30 mg IAP to diet inhibits Enterobacteriaceae population and suggests a potential effect in mitigating intestinal injuries, as observed in piglets in the NC for some of the parameters investigated.

摘要 本研究旨在评估日粮中添加肠道碱性磷酸酶（intestinal alkaline phosphatase, IAP）对产肠毒素性大肠杆菌（Escherichia coli）攻毒仔猪的细菌种群数量、消化器官内容物pH值、组织病理学特征、促炎标志物、肝糖原储备及腹泻发生率的影响。选取64头杂交仔猪（初始体重7.16±0.28 kg，日龄25日龄），采用完全随机区组设计分为4个处理组：阴性对照组（negative control, NC）、阴性对照组+抗生素组（antibiotic, ANT）、阴性对照组+15 mg IAP/kg日粮、阴性对照组+30 mg IAP/kg日粮，每个试验单元含2头仔猪，共设8个重复。试验第15天，所有仔猪经口攻毒6 mL浓度为10^6 CFU/mL的产肠毒素性大肠杆菌K88（enterotoxigenic Escherichia coli K88）溶液。试验周期共19天。试验结束后屠宰各组仔猪（每处理组6头）。
30 mg IAP组仔猪盲肠与结肠中的肠杆菌科（Enterobacteriaceae）数量显著低于抗生素组、阴性对照组及15 mg IAP组。肠系膜淋巴结（mesenteric lymph nodes, MLN）黏附的肠杆菌科数量在抗生素组仔猪中高于其余所有处理组。阴性对照组与抗生素组仔猪盲肠中的乳酸菌（lactic acid bacteria, LAB）数量更高。肠系膜淋巴结中，抗生素组与30 mg IAP组仔猪的乳酸菌数量高于15 mg IAP组。日粮添加30 mg IAP的仔猪，其组织坏死程度相较于阴性对照组或抗生素组呈降低趋势。日粮添加30 mg IAP的仔猪，腹泻发生率在攻毒前相较于15 mg IAP组、攻毒后相较于其余所有处理组均显著降低。
综上，日粮中添加30 mg IAP可抑制肠杆菌科种群数量，并显示出缓解肠道损伤的潜在效果，这一点在阴性对照组仔猪的部分受试参数中已得到印证。