[Mount Forest, Ont.] – Broiler producers are experiencing problems with a new virus that causes chicken’s legs to twist outward, leaving them crippled.
Dr. Mike Joyce, one of the leading poultry veterinarians in Ontario, said he began seeing this disease in April and May and the incidence has soared since then.
He said vaccination at the hatchery level appears to be a poor strategy; he recommends vaccination at eight days old, an increase in Biotin (vitamin B) and thorough barn cleaning and disinfection.
The between-flocks barn cleanup is no guarantee that the virus is gone because it could come with a new flock.
Even vaccination is only partially effective because the vaccine doesn’t raise immunity levels for all strains of this virus.
In a briefing on the disease situation last year and the outlook for this year, he said yolk sacculitis continues to be the most prevalent disease.
He recommends reducing the pathogen load in the barn – a thorough cleanout and disinfection and getting diseased and dead birds out of the flock – and treating the flock when the birds are four to five days old and sometimes up to eight days old.
Don’t use neomycin nor tetracycline antibiotics because they won’t work, he said. Stepping up the barn heat a degree or two and giving the birds more floor space helps.
E. coli septicemia, or hard heart, was the second-most-prevalent disease he saw in his practice last year and, again, he said more space and a bit warmer barn help reduce the incidence. Feeding high levels of Vitamin E will help boost the birds’ immune systems.
“We are losing the battle” against coccidiosis, he said. Its greatest impact is lowering the immune system so other infections and diseases emerge as killers.
“We will have to use more vaccines,” he said of the increasing incidence of antibiotic resistance.
Feed has become so expensive it pays to treat flocks with mortality rates lower than the four per cent level that used to be considered tolerable, he said.
Inclusion body hepatitis was a big issue in 2008 and 2009, but “went away” when hatcheries adopted industry-wide vaccination in 2011. Now it’s beginning to return, Joyce said.
He wishes hatcheries would return to industry-wide vaccination of all breeder flocks. This disease is a strong immune suppressant, he said.
There is a new strain of Infectious viral bronchitis in the province, he said. He recommends farmers require their hatchery to vaccinate with MA5 at the hatchery, that farmers maintain tight biosecurity, reduce stress and back off on nutritional density that pushes birds hard.
And, finally, he briefed farmers on “kinky back gait” which arises from VOA (endococcus seconum). It has come with hatching eggs from the United States, he said.
He was seeing two to three cases a month last year, but more in January.
“Don’t use penicillin,” he warned, because even though it’s effective to treat this disease, it will result in a population explosion of E. coli that will be a greater threat to the flock.
Joyce says there are many theories about the stresses that trigger this disease, but he disagrees with those who blame vaccination for coccidiosis. He thinks it’s linked to Ross 308 birds and said it was first identified in 2006 in Ross breeder males in the U.S.
It’s a virus that migrates from the bird’s gut to the bloodstream and then attacks the spinal chord.