Effects of yeast-dried milk and spray-dried porcine plasma products on growth performance, immunity, and gastrointestinal health of nursing and nursery pigs

Antibiotics are normally added in nursery diets to improve growth and pig health. However, the use of in-feed antibiotics is becoming more restricted due to the concern over health safety issues in humans. Therefore, alternatives for antibiotics are needed. In this dissertation, 7 experiments were conducted to evaluate dietary and managerial strategies to improve growth and health of nursing and nursery pigs. Four experiments were conducted to evaluate effects of feeding creep diets containing yeast-dried milk (YDM) product on growth, fecal microbiota, and serum IgA of nursing and nursery pigs. The exposure of creep feed containing YDM to nursing pigs may affect weaning BW, ADG, ADFI, total Lactobacillus , and its composition. The amount of creep feed consumption in the nursing period may result in the increased serum IgA. Three experiments were conducted to evaluate: 1) effects of spray-dried porcine plasma (SDPP) on growth, immunity, antioxidant capacity, gut integrity, and fecal microbiota of nursery pigs; 2) effects of porcine plasma on the proliferation of porcine jejunal epithelial cells; and 3) effects of SDPP on gene expression and secretion of anti- and pro-inflammatory cytokines by alveolar macrophages. Feeding SDPP increased BW, ADG, ADFI, G:F in the first week postweaning and enhanced gut integrity and enterocyte proliferation. Feeding SDPP altered the fecal microbial communities at the family, genus, and OTU levels; however, the shift of microbes depended on pig age. Lactic acid- and butyric acid-producing bacteria including Lactobacillus delbrueckii, Ruminococcus albus, Clostridium thermocellum, Clostridium saccharoperbutylacetonicum/beijerinckii, and Megasphaera elsdenii were increased in SDPP-fed pigs. At the end of experiment, feeding SDPP decreased Clostridiaceae and Clostridium difficile. In conclusion, this dissertation elucidated some of the mechanisms by which creep feeding, YDM, and SDPP improve growth and health of nursery pigs. It also demonstrated that the positive effects of SDPP on growth are mediated in part by the enhancement of gut integrity, enterocyte proliferation, and modulation of gut microbiota