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Field trial results with new NE toxoid detailed in technical services bulletins

The results of field trials with the new Clostridium perfringens type A toxoid for control of necrotic enteritis (NE) in broilers are detailed in two new technical service bulletins from Schering-Plough Animal Health.

“Clostridium perfringens Type A Toxoid: Field Efficacy Without Sub-Therapeutic Antibiotics. Part I: Coccidiosis Vaccine Trials” is about the use of the new NE vaccine by a commercial, antibiotic-free broiler integrator.

The NE vaccine was administered to breeder pullets, which convey immunity against C. perfringens — the cause of NE — to their broiler progeny. The only protection against coccidiosis that all broilers in the trial had was the Coccivac-B vaccine. The trial results show that the NE vaccine provided significant protection against C. perfringens in antibioticfree broilers.

In fact, broilers from hens that had not received the NE toxoid had 47% higher odds for mortality between 22 and 28 days compared to broilers from hens that received the NE toxoid. The odds for mortality during cold weather were an astounding 73% higher during the same time period in broilers without maternal protection against the alpha toxin.

Both the odds ratio and the relative risk compare the relative likelihood of an event occurring between two distinct groups. The relative risk is easier to interpret and consistent with the general intuition, but some designs prevent the calculation of the relative risk. In addition, there is some ambiguity about which relative risk is being compared.

When reading research that summarizes data using odds ratios or relative risks, the limitations of these measures needs to be considered.

The second new bulletin is entitled “Clostridium perfringens Type A Toxoid: Field Efficacy in Broiler Flocks Without Subtherapeutic Antibiotics. Part II: Ionophore Trials.” These trials were conducted at farms where NE had been a sporadic problem. Broilers from hens that received the NE toxoid demonstrated statistically significant improvements in livability, feed conversion, calorie conversion, adjusted calorie conversion and standard cost compared to broilers from hens that did not receive the NE vaccine.

Interactive calculator determines value of new toxoid for necrotic enteritis

An interactive online calculator has been designed to help individual poultry operations determine their return on investment when they use the new Clostridium perfringens type A toxoid for control of necrotic enteritis (NE) in broilers. The NE vaccine is administered to hens, which pass on immunity against C. perfringens to their broiler progeny.

Users simply punch in their own production numbers — things like vaccine cost per pullet, the labor cost per pullet, the number of eggs per hen, the average hatchability rate and the average live weight, number of broilers placed per week — and the calculator computes the anticipated weekly and annual return.

Marcelo Lang, poultry marketing director for Schering- Plough Animal Health, says the cost of subclinical NE alone has been estimated to be about US $0.05 per bird, which far exceeds the investment in vaccinating breeder flocks with Clostridium perfringens type A toxoid.

One 500 mL bottle of the NE vaccine treats 500 pullets on a two-shot treatment schedule. If it is assumed that each hen will produce 156 fertile eggs — a common industry average — with an average hatchability rate of 84% or 131 chicks per hen, the cost of the vaccine is estimated to be about $0.003 or a quarter of a penny per broiler chick.

At three large-bird complexes involving more than 26 million broilers, use of the NE vaccine resulted in improved livability and reduced production costs, yielding a return on investment determined to be 8:1, he says. However, “Each poultry operation is going to have different factors affecting costs and outcome. The calculator will help determine the vaccine’s value for individual operations,” Lang says.