A mixture of Lactobacillus casei, Lactobacillus lactis, and Paenibacillus polymyxa reduces Escherichia coli O157:H7 in finishing feedlot cattle.
A direct-fed microbial (DFM) containing Paenibacillus polymyxa, Lactobacillus casei, and Lactobacillus lactis was fed to cattle (n = 120) to determine impacts on shedding and survival of Escherichia coli O157:H7 in feces. Cattle were individually penned and fed diets containing 0 (control), 4 × 10(7) CFU (DFM-4), 8 × 10(7) CFU (DFM-8), or 1.2 × 10(8) CFU (DFM-12) lactobacilli per kg of dietary dry matter over 84-day fall-winter growing and 140-day spring-summer finishing periods. Fecal grab samples were collected from cattle at 28-day intervals, E. coli O157:H7 was detected by immunomagnetic separation, and isolates were compared by pulsed-field gel electrophoresis. During the growing period, feces negative for E. coli O157 from each dietary treatment were inoculated with 10(5) CFU/g nalidixic acid-resistant E. coli O157:H7 and were incubated at 4 and 22(u) C for 11 weeks. Fecal pH and fecal dry matter were measured on days 0, 1, 3, and 7 and weekly thereafter, with E. coli O157:H7 enumerated through dilution plating. Treatment with DFMs did not affect survival of E. coli O157:H7 in feces or fecal pH (P > 0.05). Only one steer was positive for E. coli O157:H7 during the growing period, but during the finishing period, DFM-8 and DFM-12 reduced the prevalence of E. coli O157:H7 in feces (P < 0.05). Feeding DFMs also reduced the frequency of individual steers shedding E. coli O157:H7 during finishing (P < 0.05), with control steers shedding E. coli O157:H7 up to four times, whereas DFM-12 steers shed E. coli O157:H7 a maximum of twice. Treatment with DFMs influenced pulsed-field gel electrophoresis profiles; steers that were fed DFM-8 and DFM-12 shed more diverse subtypes of E. coli O157:H7 than did control or DFM-4 steers. Because a companion study found linear improvement in performance with increasing dosage of DFMs in the first 28 days of the growing period, targeted use of DFM-12 during this time and for the final 1 or 2 weeks prior to slaughter may optimize performance and reduce E. coli O157:H7 while minimizing feed costs.
Alberta Agriculture and Rural Development, Lethbridge, Alberta, Canada T1J 4V6.
Kim
K
Stanford
Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada VOH 1ZO.
Susan
S
Bach
Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada T1J 4V6.
John
J
Baah
Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada T1J 4V6. tim.mcallister@agr.gc.ca.
Tim
T
McAllister
D000821:Animal Feed / Q000032:analysis / Q000382:microbiology; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000517:prevention & control*; D015169:Colony Count, Microbial; D004927:Escherichia coli Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000145:classification / Q000302:isolation & purification* / Q000502:physiology; D005243:Feces / Q000382:microbiology; D005260:Female; D007778:Lactobacillus / Q000502:physiology*; D007780:Lacticaseibacillus casei / Q000502:physiology*; D008297:Male; D056507:Paenibacillus / Q000502:physiology*; D019936:Probiotics / Q000008:administration & dosage*