Objective—To evaluate, under field conditions, the effects of a commercial porcine circovirus type 2 (PCV2) vaccine on mortality rate and growth performance in a herd infected with PCV2 that had a history of porcine circovirus disease.
Design—Randomized controlled clinical trial.
Animals—485 commercial, cross-bred, growing pigs.
Procedures—Prior to weaning, pigs were randomly assigned within litter to a vaccination or unvaccinated control group. Pigs in the vaccination group were given a commercial PCV2 vaccine at weaning and 3 weeks later. Mortality rate was recorded, and pigs were weighed prior to vaccination, when moved from the nursery, and prior to marketing. Infection status was assessed by serologic testing and detection of viral DNA in serum.
Results—Compared with control pigs, pigs vaccinated against PCV2 had a significantly lower mortality rate during the finishing phase, significantly higher average daily gain during the finishing phase, and significantly lower likelihood of being lightweight at the time of marketing. For vaccinated pigs, overall mortality rate was reduced by 50% and average daily gain during the finishing period was increased by 9.3%. At the time of marketing, vaccinated pigs weighed an average of 8.8 kg (19.4 lb) more than control pigs, without any difference in days to marketing. Serum PCV2 antibody titers increased in control pigs, and PCV2 DNA was detected, indicating active PCV2 infection.
Conclusions and Clinical Relevance—Results suggested that vaccination against PCV2 was effective at reducing mortality rate and improving growth performance among pigs in a herd infected with PCV2.
Objective—To describe the frequency and distribution
of Escherichia coli O157:H7 in the feces and environment
of cow-calf herds housed on pasture.
Sample Population—Fecal and water samples for 10
cow-calf farms in Kansas.
Procedure—Fecal and water samples were obtained
monthly throughout a 1-year period (3,152 fecal samples
from 2,058 cattle; 199 water samples).
Escherichia coli O157:H7 in fecal and water samples
was determined, using microbial culture.
Results—Escherichia coli O157:H7 was detected in
40 of 3,152 (1.3%) fecal samples, and 40 of 2,058
(1.9%) cattle had ≥ 1 sample with E coli. Fecal shedding
by specific cattle was transient; none of the cattle
had E coli in more than 1 sample. Significant differences
were not detected in overall prevalence
among farms. However, significant differences were
detected in prevalence among sample collection
dates. Escherichia coli O157:H7 was detected in 3 of
199 (1.5%) water samples.
Conclusions and Clinical Relevance—Implementing
control strategies for E coli O157:H7 at all
levels of the cattle industry will decrease the risk of
this organism entering the human food chain.
Devising effective on-farm strategies to control E coli
O157:H7 in cow-calf herds will require an understanding
of the epidemiologic characteristics of this
pathogen. (Am J Vet Res 2000;61:1375–1379)