A trial in the US designed to test the Clostridium perfringens type A toxoid vaccine under real-world conditions demonstrated that the vaccine lowers the risk for NE mortality, according to Dr. Charlie Broussard, a veterinarian with Intervet/Schering-Plough Animal Health.

The poultry company that took part in the trial was moving toward antibiotic-free (ABF) production and had an established vaccination program for coccidiosis control, Broussard said.

NE was a recurring problem, however, particularly during cold winter months, and the company’s poultry houses lacked ideal environmental control, he said.

The trial involved about 4.6 million control birds and 1.3 million broilers that were progeny of breeders vaccinated with the C. perfringens type A toxoid vaccine, which is conditionally licensed in the US and awaiting approval in other major poultry markets. The control group had some birds from hens vaccinated with the NE vaccine; this would be expected to reduce the gap between the two groups in terms of NE mortality, but there was still a significant difference in favor of the non-control group, Broussard said.

The trial was carried out between August and February (late summer through late winter). For each group of broilers grown, investigators recorded mortality for three consecutive age periods — 8 to 14 days, 15 to 21 days and 22 to 28 days.

NE deaths occurred in each of these periods, especially the 22-to-28-day period, Broussard said, but trend lines showed mortality was consistently lower for birds from hens vaccinated with the NE vaccine. Overall, mortality for both groups was higher during the cooler months, but among the group from the vaccinated hens, the trend line remained lower by a margin of 0.25% to nearly 0.5%. Birds in this group also had a far smoother mortality pattern, with fewer spikes in the graph.

“Looking at it another way, the chance of mortality for the broilers of vaccinated hens was 47% lower than for the controls throughout the entire trial,” he said. “During cooler months, this advantage grew to 72%.”

In an interview with Intestinal Health after his presentation, Broussard said that the poultry company that hosted the field trials was very encouraged by the results and was continuing with the NE vaccine as part of its ABF production plans. “In fact, they are taking it one step further,” Broussard added. “As ABF production becomes more mainstream, they are moving toward a totally organic system. Sourcing good-quality organic feed will be key to their success in that market.”

Looking ahead, Broussard said that the C. perfringens type A toxoid vaccine could eventually become integrated into the routine care of many breeders. “C. perfringens type A toxoid vaccine is a standalone product now, but there are some exciting possibilities for synergies with other vaccines. This would stream-line production and help address labor cost issues.”

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