Submitted to: Xenotransplantation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2005
Publication Date: 3/1/2005
Citation: Loynachan, A.T., Pettigrew, J.E., Wiseman, B.S., Kunkle, R.A., Harris, D.L. 2005. Evaluation of a diet free of animal protein in germfree swine. Xenotransplantation. 12:149-155. Interpretive Summary: Basic research into the potential to use organs harvested from swine for the purpose of transplantation to save human lives has identified potential immunological and transmissible infectious disease obstacles. BSE has been transmitted to swine following intracerebellar inoculation, indicating the potential susceptibility of pigs to prion infections. Although neither natural nor experimental oral transmission of spongiform encephalopathies has been recorded in pigs, concerns about the transmission of prion proteins in feed have led to the development of a diet free of animal protein (DFAP). This study describes a method to rear neonatal pigs in a manner that precludes exposure to environmental microorganisms and animal-derived proteins. Twenty pigs were derived by Cesarian-section and housed in sterile bubble-pens. Duplicate trials were conducted in which germ-free pigs or pigs intentionally colonized exclusively with the bacterium Lactobacillus paracasei subspecies paracasei were fed either a traditional milk-based diet (Esbilac) or the experimental DFAP. On the whole, the pigs in all groups remained healthy, however, two pigs fed the DFAP developed mild diarrhea and gained less weight. The pigs were euthanized at 16 days of age. Examinations revealed no evidence of contamination or disease. The use of the probiotic, Lactobacillus paracasei, did not confer any measurable growth advantage to pigs fed either diet. The experimental DFAP was capable of sustaining life, but was not as efficacious as the conventional milk-based diet as based upon weight gain and feed-conversion.
Technical Abstract: Two experiments were conducted in which germfree pigs or pigs monoassociated with Lactobacillus paracasei subspecies paracasei were fed either a traditional milk-based diet (Esbilac) or an experimental diet free of animal protein (DFAP). Throughout the 16-day study, animals' general disposition, total weight gain, feed conversion, and bacterial contamination were monitored. At the conclusion of the study the animals were euthanized, necropsied and tissues sampled for L. paracasei isolation. General pig disposition remained consistent between treatment groups and trials, except for two animals that developed mild diarrhea during trial 1. All pigs remained viable during the study irrespective of the diet fed or probiotic inoculation. Germfree pigs fed the Esbilac diet gained on average a total of 1034 (+/- 63.0) g, and had a feed conversion ratio of 0.17 (+/- 0.01) g of gain per 1 ml of diet. Germfree pigs fed the experimental diet gained on average a total of 599 (+/- 151) g, and had a feed conversion ratio of 0.10 (+/- .02) g of gain per 1 ml of diet. Monoassociated pigs fed the Esbilac diet gained on average a total of 862 (+ 70.3) g, and had a feed conversion ratio of 0.14 (+/- 0.01) g of gain per 1 ml of diet. Monoassociated pigs fed the experimental diet gained on average a total of 563 (+/- 96.8) g, and had a feed conversion ratio of 0.09 (+/- 0.02) g of gain per 1 ml of diet. L. paracasei established extensively in pigs fed either the Esbilac or experimental diets. L. paracasei had no effect (p>0.05) on piglet growth and did not display any interactions based on the diet fed. Statistical differences (p<0.05) were noted on measured growth parameters between trial 1 and 2, and on measured growth parameters based on the diet fed. In conclusion, a diet free of animal protein has been developed and has been shown to be capable of sustaining life in piglets up to 16 days of age.