Vaccinating cuts colibacillosis losses in broilers

Vaccinating cuts colibacillosis losses in broilers

Trials show vaccinating broilers against E. coli reduces mortality and treatment duration while improving feed conversion and bodyweight.

PRODUCERS can expect reduced losses from colibacillosis and economic benefits by vaccinating broilers against Escherichia coli, according to Dr. Kalen Cookson, a technical services veterinarian for Zoetis Inc.

"E. coli infection and resulting colibacillosis is still a common and costly bacterial infection of poultry," he said. "Producers have tried to control the disease by tackling other infections that predispose (birds) to E. coli, like mycoplasma infection, and by using antimicrobials, but there's been limited success."

In layers, E. coli vaccination has been widely used in the U.S. and is credited with a marked reduction in peritonitis-related mortality.

In broilers, the benefits of vaccinating against E. coli have been demonstrated in controlled challenge studies, and there is now corroborating evidence from field trials, Cookson said.

He cited Zoetis-sponsored field studies with broilers on two continents that were designed to test the efficacy of the modified-live vaccine Poulvac E. coli, a "non-reactive" vaccine.

"There were a variety of conditions on the farms, but one thing in common was a higher-than-normal E. coli disease challenge," Cookson said.

 

U.S. trial

In a U.S. trial, investigators administered the vaccine to more than 4 million broiler chicks at hatch and then compared their performance to a control group of unvaccinated chicks hatched the previous week that were treated in ovo with the antibiotic gentamycin.

Chicks that received the E. coli vaccine had a better adjusted feed conversion and fewer condemnations compared to controls, yielding a 51 cents/lb. advantage (Table 1), Cookson said.

Vaccinated chicks also had significantly less disease incidence compared to controls and needed fewer antibiotic treatments and for a shorter duration of time, he added.

For example, vaccinated broilers required 2.6 days of antibiotic treatment compared to 6.8 days among the broilers that weren't vaccinated.

 

North African trials

A field trial conducted in North Africa involved two broiler houses on the same farm, each with 8,000 birds, that had a history of high mortality due to E. coli.

Investigators treated all birds with an antibiotic in ovo. Next, they vaccinated the birds in one of the houses with the E. coli vaccine at three days of age, and birds in the other house served as a control and were treated with enrofloxacin for the first three days of life, Cookson said.

At 40 days of age, he said the vaccinated birds had lower total mortality, better bodyweights and a better feed conversion ratio compared to the unvaccinated birds (Table 2).

A second broiler field trial was conducted in North Africa with 18 paired-house sets on 15 different farms that had a history of E. coli colibacillosis, but this time, no preventive in ovo or in-feed antibiotics were administered.

Compared to controls, vaccinated birds had an overall better average daily gain and feed conversion ratio as well as fewer E. coli lesions.

Also, when birds needed an antibiotic treatment, it was necessary for a shorter duration, said Cookson, who presented data from the trials at the 2013 World Veterinary Poultry Assn. conference held in Nantes, France.

"These field trials show that (E. coli vaccine) can help reduce losses in broilers from pathogenic E. coli when measured by livability, growth rate, feed conversion and less antibiotic use," he said.

The vaccine, which can be administered by coarse or fine spray, is approved in the U.S. for use in chickens and turkeys.

 

1. Results from U.S. trial

 

Adjusted

Mortality

Total

Cost,

 

feed conv.

after week 1, %

condemnations, %

cents/lb.

Controls

1.83

3.50

1.06

Vaccine

1.79

3.14

0.76

Advantage with vaccine

0.04

0.36

0.30

0.51

 

2. Results from first North Africa field trial

 

Total mortality, %

Bodyweight, kg

Feed conversion ratio

Controls

4.75

2.085

1.99

Vaccine

4.24

2.179

1.83

Advantage with vaccine

0.51

0.094

0.16

 

Volume:86 Issue:27

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