Niewold T A, van Dijk A J, Geenen P L, Roodink H, Margry R, van der Meulen J
Animal Sciences Group of Wageningen University and Research, P.O. Box 65, Lelystad, The Netherlands.
Vet Microbiol. 2007 Oct 6;124(3-4):362-9. doi: 10.1016/j.vetmic.2007.04.034. Epub 2007 Apr 29.
In order to establish the mechanism of spray dried plasma powder (SDPP) in improving pig health and performance, a diet containing either 8% SDPP, spray dried immune plasma powder (SDIPP), or control protein (soybean and whey) ration was fed to piglets in an experimental model of enterotoxigenic Escherichia coli F4 (ETEC) post-weaning diarrhoea (PWD). SDIPP was obtained from pigs immunized with a vaccine containing ETEC fimbrial subunit F4 and heat-labile toxin (LT), and SDPP from non-immunized controls. Average daily growth (ADG) was determined, and daily samples of rectal faeces were assessed for diarrhoea (as percentage of dry matter), and ETEC excretion (in CFU/g). SDPP and SDIPP significantly (p<0.05) reduced diarrhoea, and SDIPP significantly reduced ETEC excretion. ADG was not significantly (p>0.05) affected. After the experiment, 30% of piglets tested F4 receptor positive (F4R+). A significant correlation between F4R status and morbidity was found. In F4R+ animals, SDIPP significantly improved diarrhoea and ADG, and decreased ETEC excretion, and SDPP significantly improved diarrhoea and ADG. Surprisingly, SDPP reduced diarrhoea in F4R+ animals without significant reduction of ETEC excretion, which is most likely related to the presence of anti-LT antibodies in SDPP. The results show that oral protection against ETEC by SDPP is attributable to spontaneous antibodies, in this case anti-LT antibodies. Furthermore, the results indicate that the combination of anti-LT and anti-F4 antibodies as in SDIPP is most effective in ETEC prevention. Finally, the F4R distribution in the herd should be taken into account to correctly assess efficacy.
为了确定喷雾干燥血浆粉（SDPP）改善仔猪健康和生产性能的机制，在产肠毒素大肠杆菌F4（ETEC）断奶后腹泻（PWD）的实验模型中，给仔猪饲喂含有8% SDPP、喷雾干燥免疫血浆粉（SDIPP）或对照蛋白（大豆和乳清）日粮。SDIPP取自用含有ETEC菌毛亚基F4和不耐热毒素（LT）的疫苗免疫的猪，SDPP取自未免疫的对照猪。测定平均日增重（ADG），并每天采集直肠粪便样本，评估腹泻情况（以干物质百分比表示）和ETEC排泄量（以CFU/g表示）。SDPP和SDIPP显著（p<0.05）减少腹泻，SDIPP显著减少ETEC排泄。ADG未受到显著（p>0.05）影响。实验结束后，30%的仔猪F4受体检测呈阳性（F4R+）。发现F4R状态与发病率之间存在显著相关性。在F4R+动物中，SDIPP显著改善腹泻和ADG，并减少ETEC排泄，SDPP显著改善腹泻和ADG。令人惊讶的是，SDPP降低了F4R+动物的腹泻，但未显著减少ETEC排泄，这很可能与SDPP中存在抗LT抗体有关。结果表明，SDPP对ETEC的口服保护作用归因于自发抗体，在这种情况下是抗LT抗体。此外，结果表明，如SDIPP中抗LT和抗F4抗体的组合在预防ETEC方面最有效。最后，应考虑猪群中F4R的分布，以正确评估疗效。
