An intensive European study has pinpointed management factors that can yield the best performance results in broilers vaccinated against coccidiosis.

The attenuated coccidiosis vaccine Paracox-5 has proved to be an effective way to protect broilers from coccidiosis since its 2000 introduction in Europe and especially since regulators prohibited the use of in-feed antibiotic growth promoters, said Italy’s Dr. Luciano Gobbi, a technical manager for Intervet/Schering-Plough Animal Health.

However, the results of a study conducted on an integrator’s commercial farms in northern Italy demonstrate that attention to certain management practices can significantly boost performance in coccidiosis-vaccinated birds, the veterinarian said.

The study involved some 2 million broilers vaccinated at day 1 with Paracox-5, which was administered with a specially designed hatchery spray cabinet, Gobbi said.

The efficacy of the vaccine was based on both clinical observations, such as mortality and coccidiosis breaks, and performance results, specifically final live weight and feed conversion. Performance parameters were then correlated against four sets of factors:

1. Effectiveness of vaccine distribution in the hatchery spray cabinet



2. Quality of bird-management practices during full grow-out



3. Influence of the genetic line on susceptibility to necrotic enteritis



4. Use of tactical antibiotic chemoprophylaxis

Accurate vaccination essential

The accuracy of vaccine administration made a clear impact, the study showed. More accurate spray administration alone resulted in a 30-gram advantage in final live weight, a feed-conversion ratio (FCR) advantage of 0.045 and mortality was lower by 0.7%, Gobbi reported.

When not uniformly sprayed, some birds do not receive initial exposure to vaccine oocysts. Instead, they are exposed to oocysts for the first time in 4 or 5 days, when the first coccidial cycling occurs in birds that received the vaccine. This delays establishment of immunity, resulting in poorer performance and an extra half-day to reach market weight, he explained.

Best and worst management practices

The analysis of management practices was revealing, Gobbi continued. Farms were classified into groups of the “best 10” and “worst 10” regarding management level. Good management was found to minimize the impact of necrotic enteritis, a multifactorial disease. farms in northern Italy demonstrate The best management groups also had a final live weight that was nearly 100 grams more and an FCR better by 0.077 compared to the 10 worst groups. In addition, mortality was 1.5% higher in the worst groups compared to the 10 best groups, he said.

In an interview with Intestinal Health, Gobbi said that good management covers everything from the hours before the day-old chicks are placed until they go to slaughter.

“Something as simple as temperature control is very important to getting birds off to the right start,” he said. “If the temperature is as little as 2 degrees lower than it was in the hatchery and during transport, chicks will gather around heat lamps and pile onto each other. That stops them from eating and drinking.”

In addition to careful temperature management, farm managers must look after basics such as ensuring birds have good access to food plates and properly functioning water nipples, Gobbi said.

“The first 10 days are critical, and up to 80% of the investment in management should be during this brooding phase,” he said.

Considering the physiology of the birds, the physical state of the starter or pre-starter rations can have a big impact, he added. It is important that pelleted feed rations are “not too hard and not too soft” when crushed — otherwise more robust birds select granules out of the ration, leaving some birds to get only part of the formulation.

Genetic line matters

The influence of the vaccinated bird’s genetic line on performance was also clear in the study, Gobbi said.

Genetic selection for muscle development can divert available amino acids from the immune system. “Although it hasn’t been proven scientifically, there are some perceptions that certain genetic lines are more susceptible to lecithinase-C, which is produced by the alpha-toxin of Clostridium perfringens type A,” he reported.

Some genetic lines were also less tolerant of sudden feed changes. For instance, when birds from certain lines were switched from a grower to finisher ration, they would sulk 1 to 2 days and pick at litter, thus ingesting feces and exposing themselves to greater gut-health challenges, he said.

The level of response to the presence of feed mycotoxins, which are an immunosuppressant, appeared to be genetically linked, with some lines more likely to refuse feed containing the toxins, Gobbi noted.

When other factors such as the hatchery source were equalized, there were clear performance differences between two breed lines identified in the Italian study. The relative advantages were consistent for liveweight, FCR and mortality, he said.

The final parameter evaluated — therapeutic antibiotic therapy — revealed that treated broilers fared slightly better than the birds that did not receive therapeutic antibiotics.

Gobbi concluded that the study highlighted the importance of field management in achieving successful coccidiosis vaccination. “The integrator involved in our study has standard operating procedures, but the human factor comes into play when applying these procedures,” he said. “When birds are vaccinated and managed well, intestinal health problems in all flocks can be prevented or minimized in the long term.”

Regresar a European Edition (#2)