Field trials show practical, economic benefits of E. coli vaccine in broilers
Recent studies on two continents have demonstrated that a modified-live vaccine reduced losses from Escherichia coli in broilers, even when the disease challenge was strong.1
The studies were conducted on farms in the US and North Africa. “There were a variety of conditions, but one thing in common was a higher than normal E. coli challenge,” said Kalen Cookson, DVM, MAM, a technical services veterinarian for Zoetis.
In the US trial, investigators administered the vaccine Poulvac® E. coli to more than 4 million broilers at hatch. They then compared performance to unvaccinated chicks hatched the previous week that were treated in ovo with the antibiotic gentamycin.
Chicks that received Poulvac E. coli and no gentamycin had a better adjusted feed conversion, lower mortality after week 1 and fewer condemnations compared to controls, yielding a US 0.51 cents (€ 0.39) advantage per pound. They also had significantly less disease and needed less antibiotic treatment and for a shorter duration of time, he said.
One of the field trials in North Africa involved two broiler houses with 8,000 birds each on a farm with high E. coli mortality. Investigators treated all birds with an antibiotic in ovo, and then vaccinated one house with Poulvac E. coli at 3 days of age. The other house was not vaccinated but was treated with enrofloxacin for the first 3 days of life.
At 40 days of age, vaccinated birds had lower total mortality, better bodyweight and a better feed-conversion ratio (FCR) compared to unvaccinated birds, Cookson said.
In another field trial in North Africa involving 15 different farms with a history of E. coli colibacillosis, no preventive in ovo or in-feed antibiotics were administered. Compared to controls, broilers vaccinated with Poulvac E. coli had an overall better average daily gain and FCR and fewer E. coli lesions. When antibiotic treatment was needed, it was necessary for a shorter duration, Cookson said.
1 Cookson K, et al. A modified live Escherichia coli vaccine reduces mortality and colibacillosis in broiler field trails. 2013 World Veterinary Poultry Association Conference, Nantes, France. FDAH Study #B510-09-RFt.R (US trial report) and FDAH Study #3113C- 39-10-347 (Moroccan trial report).