Welch Michael W, Cross Amanda J, Solar Diaz Iara D P, Johnson Danielle C, Parr Eric, Rathje Tom A, Borg Randy C, Boler Dustin D
Carthage Veterinary Service Ltd, Carthage, IL 62321, USA.
DNA Genetics, Columbus, NE 68601, USA.
Transl Anim Sci. 2025 Jan 17;9:txaf004. doi: 10.1093/tas/txaf004. eCollection 2025.
Enterotoxigenic (ETEC) is a leading cause of postweaning diarrhea (PWD) and mortality of weaned pigs. The objective of this study was to evaluate genetic resistance of the polymorphism at nucleotide 307 (M307) in the gene, to F18 infection considering different genotypes. A total of 179 pigs were used for this study. Pigs were genotyped for susceptibility to F18+ prior to the trial. Treatments included: genotype M307-heterozygous for susceptibility (A), genotype M307-homozygous susceptibility (B), or genotype M307-homozygous for resistance (C). Pigs were weighed, assigned to pens based on genotype, and allowed to acclimate for 3 d prior to the challenge. On days 4, 5, and 6, pigs were inoculated intraorally at the oropharynx with an F18+ isolate at a geometric mean concentration of 9.8 × 10. Growth rate (average daily gain [ADG]), feed intake (average daily feed intake), and gain-to-feed ratio (G:F) were calculated by pen. All pigs were humanely euthanized at the end of the trial. Two fixed sections of ileum and distal jejunum were collected from a subpopulation and tested by in situ hybridization (ISH) to evaluate F18+ adherence. Fresh ileum samples were used for enumeration of F18, total , and total bacteria by real-time polymerase chain reaction. Mortality rates during the trial were 26.7% for genotype A, 18.3% for genotype B, and 0.0% for genotype C (< 0.01). Starting weights prior to inoculation were not different ( = 0.29) among genotypes. Overall, pigs from genotype C grew 223 g/d faster ( = 0.04) than genotype A. Pigs from genotype C tended to grow 185 g/d faster ( = 0.09) than genotype B. G:F for genotype C (0.74) was 23% greater (< 0.01) than G:F for genotype A (0.60) and tended to be 12% greater ( = 0.07) than genotype B (0.66). There were no differences in ADG or G:F between genotypes A and B. F18-specifc Cq units were decreased by 7.74 and 6.47 in genotypes A and B compared with genotype C ( ≤ 0.03). Signal by ISH was increased by 14.0-fold in genotype A compared with genotype C ( = 0.02). Adherence was not different among genotypes ( = 0.40). Genotype A had greater mortality and poorer growth performance than genotype B or C. Genotype C had no mortalities during the trial, grew faster, was more feed efficient, and had less F18 in the ileal mucosa compared with genotype A. Resistant genotypes provide an opportunity to reduce PWD and mortality due to an F18+ infection.
产肠毒素大肠杆菌（ETEC）是断奶仔猪断奶后腹泻（PWD）和死亡的主要原因。本研究的目的是考虑不同基因型，评估基因中第307位核苷酸（M307）多态性对F18感染的遗传抗性。本研究共使用了179头猪。在试验前对猪进行F18+易感性基因分型。处理包括：M307杂合易感性基因型（A）、M307纯合易感性基因型（B）或M307纯合抗性基因型（C）。对猪称重，根据基因型分配到栏中，并在攻毒前适应3天。在第4、5和6天，以几何平均浓度9.8×10经口在口咽部给猪接种F18+分离株。按栏计算生长率（平均日增重[ADG]）、采食量（平均日采食量）和料重比（G:F）。试验结束时对所有猪实施安乐死。从一个亚群中采集两段固定的回肠和空肠远端组织，通过原位杂交（ISH）检测以评估F18+黏附情况。新鲜回肠样本用于通过实时聚合酶链反应对F18、总需氧菌和总细菌进行计数。试验期间，基因型A的死亡率为26.7%，基因型B为18.3%，基因型C为0.0%（P<0.01）。接种前的初始体重在各基因型之间无差异（P=0.29）。总体而言，基因型C的猪比基因型A的猪生长速度快223克/天（P=0.04）。基因型C的猪比基因型B的猪生长速度倾向于快185克/天（P=0.09）。基因型C的料重比（0.74）比基因型A（0.60）高23%（P<0.01），比基因型B（0.66）倾向于高12%（P=0.07）。基因型A和B之间的ADG或G:F无差异。与基因型C相比，基因型A和B的F18特异性Cq单位分别降低了7.74和6.47（P≤0.03）。与基因型C相比，基因型A的ISH信号增加了14.0倍（P=0.02）。各基因型之间的黏附情况无差异（P=0.40）。基因型A的死亡率高于基因型B或C，生长性能也较差。与基因型A相比，基因型C在试验期间无死亡，生长更快，饲料效率更高，回肠黏膜中的F18更少。抗性基因型为降低F18+感染引起的PWD和死亡率提供了机会。
