Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Population Health & Reproduction
Non Technical Summary
Antibiotics have been powerful tools for herd health programs of livestock industries. However, use of antibiotics in livestock industries has the potential to contribute to the spread of antibiotic-resistant pathogens in both livestock and humans, rising public health concerns. Since January 2017, FDA regulations prohibit the use of in-feed antibiotics as growth promoters in livestock and poultry. With the implementation of the new regulations of use antibiotics in feed, the challenge is increasing to maintain animal performance and keep animals healthy especially in post-weaning period. Alternatives to in-feed antibiotics that could effectively maintain animal performance and alleviate post-weaning diarrhea are an urgent need by the swine and other livestock industries. Using pig models, this project will evaluate the effects of Bacillus probiotics on growth performance and disease resistance and compare the effects to that of in-feed antibiotics. Results of the project can be used by swine and other livestock and poultry industries in developing combined strategies of alternatives to antibiotics to improve animal health and production.?
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Our long-term goal is to help the livestock industry to deploy feed-based health technologies to best effect in improving animal health. Specific aims are: 1) To determine the effects of dietary supplementation with Bacillus probiotics on performance and diarrhea resistance of weaned pigs infected with E. coli; and 2) To compare the efficacy of probiotics with that of NEO-OXY (a neomycin sulfate - oxytetracycline combination) that can be used in pigs for "treatment and control of colibacillosis caused by E. coli. This drug also used to have a label for "weight gain and improved feed efficiency".
Project Methods
Some species of Bacillus have shown great potential as probiotics in animal production. In this project, pigs will be randomly allotted to four treatments: 1) Negative control: basal diet without supplementation of antibiotics or probiotics and without E. coli challenge, 2) Positive control: same diet as negative control but with E. coli challenge, 3) Antibiotic growth promoters (AGP) diet: basal diet supplemented with 25 mg/kg NEO-OXY, and 4) Probiotics diet: basal diet supplemented with 1 × 109 cfu probiotics (Bacillus subtilis) per kg diet. A 2-phase feeding program will be used with d 0 to 14 as phase I and d 14 to 28 as phase II, therefore, 8 diets will be prepared. All diets will be formulated to meet pig nutritional requirements. The experiment will be conducted at UC Davis Teaching and Research Animal Care Services facility or the Swine Cole facility. A total of 32 weanling pigs (around 21 d old) with equal number of barrows and gilts will be used in this experiment. There will be 8replicates per treatment. Based on our previous work, a total of 4-6 individuals per treatment group were required to generate statistically valid results for immune-related measurements. These results had a statistical power ranging from 69-90% (two-tailed, α = 0.05) depending on the parameter being analyzed. To increase the statistical power to access the differences in performance and gut morphology, 8 replicates per treatment will be used in the current experiment. The sows and piglets used in this experiment will not receive E. coli vaccines, antibiotic injections, or antibiotics in creep feed. After weaning, all pigs will be randomly assigned to one of the four dietary treatments in a randomized complete block design with weight within sex and litter as the blocks and pig as the experimental unit. Pigs will be housed in individual pens for 28 days, including 7 days before and 21 days after the first E. coli challenge. After 7 days adaptation, all pigs will be orally inoculated with 3 mL F18 E. coli/day for 3 consecutive days from d 0 post-inoculation (PI). The F18 E. coli were isolated from a field disease outbreak by the University of Illinois Veterinary Diagnostic Lab (isolate number: U.IL-VDL # 05-27242). The F18 E. coli expresses heat-labile toxin, heat-stable toxin b, and Shiga-like toxins and will be given to pigs at 1010 cfu per 3-mL dose in PBS. This dose could cause mild diarrhea based on our previous research.The procedures for this experiment will be adapted from the methods we described previously. Before weaning, feces will be collected from sows with their piglets destined for this experiment. Fecal samples will be plated on blood and MacConkey agars to verify the free of β-hemolytic E. coli. All piglets will be also tested for F18 receptor status with RFLP and PCR to make sure they are sensitive with F18 E. coli. During the experiment, clinical symptoms (diarrhea score and alertness score) will be recorded twice daily from d 0 PI. The diarrhea score of each pig will be assessed visually each day by 2 independent evaluators, with the score ranging from 1 to 5 (1 = normal feces, 2 = moist feces, 3 = mild diarrhea, 4 = severe diarrhea, and 5 = watery diarrhea). The alertness score of each pig will be assessed visually with a score from 1 to 3 (1 = normal, 2 = slightly depressed or listless, and 3 = severely depressed or recumbent). Pigs will be weighed on weaning day, d 0 (first inoculation day), 7, 14, and 21 PI. Daily feed intake will be recorded throughout the experiment. Blood samples will be collected from the jugular vein of all pigs with or without EDTA to yield whole blood before E. coli challenge (d 0), and on d 7, 14, and 21 PI. Whole blood samples will be used for measuring total and differential blood cell count by CBC test. All pigs will be euthanized at the end of the experiment. Three 3 cm segments from the duodenum, the middle of the jejunum, and ileum (10 cm close to the ileocecal junction) will be collected and fixed in Carnoy's solution. The fixed intestinal tissues will be stained with high iron diamine and alcian blue and will be analyzed for cross-sectional area of sulfo- and sialomucin, the number of goblet cells per villus, villi height, and crypt depth as described previously.Data will be analyzed by ANOVA using PROC MIXED of SAS (SAS Institute Inc., Cary, NC) in a randomized complete block design with the pig as the experimental unit. The statistical model will include diet as main effect and block as random effect. Treatment means will be separated by using the LSMEANS statement and the PDIFF option of PROC MIXED. Statistical significance and tendency will be considered at P < 0.05 and 0.05 ≤ P < 0.10, respectively.