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United States Department of Agriculture

Agricultural Research Service

2011 Annual Report

1a.Objectives (from AD-416)
1. To evaluate effects of Lactobacillus acidophilus NP51 on host immune response. 2. To evaluate effects of NP51 on the prevention of MAP infection. 3. To evaluate effects of NP51 on the treatment of MAP infection.

1b.Approach (from AD-416)
Mice will be fed NP51 before and after challenge with MAP to ascertain the effectiveness in prevention or treatment of the infection and colonization of target tissues such as spleen, ileum, and mesenteric lymph nodes. The host response to NP51 will be determined by evaluation of cytokine induction alone and in tandem with MAP infection.

3.Progress Report

The objective of this collaborative agreement was to examine whether feeding a probiotic, Lactobacillus acidophilus strain NP51, to mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), would increase cell-mediated immune responses and decrease progression of MAP infection. After conducting a preliminary experiment to optimize the dose of the probiotic, mice were fed the probiotic for 45 days before they were challenged with live or heat-killed MAP for an additional 135 days. Overall, feeding the probiotic significantly increased the frequency of CD8+ cytotoxic T cells in spleens of mice infected with viable MAP. Most importantly, MAP burden was decreased in the mesenteric lymph nodes, livers, and spleens of mice fed probiotic compared to the MAP-infected controls. These results suggest that feeding probiotic modifies the immune responses and prevents progression of MAP infection in the mouse model. Incorporation of this probiotic may reduce the incidence of Johne’s disease in dairy cattle.

A study was conducted to determine effects of feeding the probiotic on general health of lactating dairy cows. Feeding the probiotic did not affect milk production but did demonstrate decreases in somatic cell counts. In addition, molar concentrations of volatile fatty acids in the rumen were observed, indicating an increase in energy availability.

Results suggest the probiotic has potential to improve nutrient digestibility, energy availability, and udder health with good implications to dairy cows in other stages of lactation and the transition period.

Progress was monitored via monthly phone calls, e-mails and meetings every 2-3 months.

Last Modified: 11/24/2015
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