2018-09-042018-09-042018-082018-08August 201http://hdl.handle.net/2346/74491The neonatal calves are extremely susceptible to enteric diseases during the first few weeks of life. According to the report form USDA, the mortality rate of newborn calves is about 10%; however, the death caused by enteric diseases accounts for 50% of mortality. On the other hand, antimicrobials are widely used in the dairy industry in the past decades; but the concern has been increased for using antibiotic in recent years. Therefore, there is more interesting to find alternatives to antibiotic use which has similar efficacy as antibiotic in decreasing diseases. Some studies have been conducted to investigate effects of those nutritional supplements on growth performance and health on swine and poultry industry. For current research, yeast cell wall, various strains of probiotic, egg protein, and hydrolyzed yeast will be investigated for effects on growth performance, innate immunity, and gastrointestinal development in young dairy calves. In first study, effects of Provia® (Bacillus coagulans 6086) and OmniGen AF® alone or in combination on growth performance, innate leukocyte responses, and enteric health of pre-weaned and immediate post-weaned dairy calves were evaluated. Treatments in this study were: CON: base milk replacer and calf starter; PV: 2 x 109 CFU/d of Bacillus coagulans 6086 in milk replaer and 2 x 109 CFU of Bacillus coagulans 6086 per kg of the base calf starter; OG: 12g/d of OmniGen-AF in milk replacer and 12 g of OmniGen-AF per kg of the base calf starter; OG+PV: supplement with both of the Bacillus coagulans 6086 and OmniGen-AF. The PV supplemented calves had greater ADG from d 71 to d 84 during post-weaning period. There were no treatment differences in the percentage of calves that scoured throughout the study. The results of this study indicated that neither Provia, Bacillus coagulans 6086 nor OmniGen-AF greatly influenced the growth performance or enteric health during the pre-weaned or immediate post-weaned periods. The impact of a blend of a strain of Lactobacillus casei and an Enterococcus faecium strain on physiological response to an oral Salmonella enterica serotype Typhimurium challenge in neonatal Jersey calves was investigated in second study. The treatments in this study were: CON: base milk replacer; CON+ST: base milk replacer with Salmonella typhimurium challenge on d 7; PRO+ST: base milk replaer with a blend of a strain of Lactobacillus casei and an Enterococcus faecium strain and challenged with Salmonella typhimurium on d 7. Serum haptoglobin and urea N concentrations were increased on d 10 in CON+ST comparing to PRO+ST. In contrast, PRO+ST had greater rectal temperature after challenge than CON+ST. Further, neutrophil percentages in PRO+ST were greater than CON+ST or CON. However, 7 of 8 calves in PRO+ST had elevated neutrophil percentages on d 10 relative to d 7, whereas 4 of 8 calves among the CON+ST had reduced neutrophil percentages on d 10 relative to d 7. The ratios of villi height to crypt depth in both of duodenum and ileum were greater in PRO+ST than CON+ST calves. These data indicated that supplementing neonatal calves with the blend of probiotics used in the current study improve the pathophysiological response and small intestinal health and development with an enteric Salmonella typhimurium challenge. The objective of final study is to determine the impacts of supplementing a blend of yeast culture, yeast extract, hydrolyzed yeast, and immunized egg antibodies on the growth performance and health of calves challenged with Salmonella typhimurium. There are 4 treatments in current study: CON: base milk replacer; CON+ST: base milk replacer with Salmonella typhimurium challenge on d 7; CA: milk replacer supplemented with 16 mL/d CalfAce; CA+ST: base milk replacer supplemented with 16 mL/d CalfAce and challenged with Salmonella typhimurium on d 7. The calves with challenge had decreased starter intakes. CalfAce supplementing calves decreased serum haptoglobin concentration. Calves supplemented with CalfAce had greater villi height to crypt depth ratio in duodenum when compared to non-supplemented calves. In conclusion, CalfAce supplementing calves reduced both of systemic and local inflammatory response and improved the gastrointestinal health.application/pdfengCalvesHealthInnate immunityGITDissertation2018-09-04Restricted until September 2019. For access, request a copy.