Optimal results

Study shows coccidiosis vaccination doesn't deter CE products from protecting birds against Salmonella enteritidis

Chapman and feathered friend in the lobby of the Center of Excellence for Poultry Science, University of Arkansas.

A team of scientists in the world's second largest poultry market, Brazil, has determined that coccidiosis vaccines do not compromise the ability of "competitive exclusion" or CE products to protect birds against Salmonella enteritidis (Se).

"We found that the actions of ACM (anaerobic cecal microflora) against cecal colonization and fecal excretion of Se are not affected by the use of coccidiosis vaccine in broiler chicks," says veterinarian and lead investigator Raphael Lucio Andreatti Filho, a professor of poultry pathology at the Universidade Estadual Paulista, Botucatu, São Paulo.

"Moreover, our results show that the ACM-coccidiosis vaccine combination can be used without reduction of the effectiveness of ACM," adds Andreatti Filho, who conducted the trial with ornithopathologists Plínio Mestrinel Junior and Homero Marcos Sampaio, plus statistician Adalberto José Crocci.

Understanding CE

CE products such as ACM help to maintain a healthy balance of microflora in the gut, thereby increasing the bird's natural resistance to disease-causing bacteria such as Se. This is important because Se is one of the most significant forms of salmonellae that is transmissible from chickens to humans.

Even when broiler performance is not compromised by Se, the organism creates a serious public health problem - namely, food poisoning.

Se also can create a health problem for young or stressed birds. (With adult birds, the Se is sometimes present, but the birds don't necessarily have the appearance of being sick.) Research also has shown that the coccidial organism E. tenella may prolong the persistence of Se in the intestine, which in turn leads to a longer period of Se exposure in feces.

Field Trial

To see if coccidiosis vaccination had any effect on the CE product, researchers in Brazil divided 120 1-dayold broiler chicks into six groups and then implemented the following protocols:

"� Group A received ACM by spraying on day 1, was vaccinated with the live oocyst vaccine Coccivac-B on day 2 and challenged with Se on day 3.

"� Group B received ACM by intraesophageal inoculation on day 1, was vaccinated with Coccivac-B on day 2 and challenged with Se on day 3.

"� Group C received ACM through the drinking water on day 1, was vaccinated with Coccivac-B on day 2 and challenged with Se on day 3.

"� Group D was vaccinated with Coccivac-B on day 2 and challenged with Se on day 3, but was not treated with ACM.

"� Group E was challenged with Se on day 3, but was not vaccinated or treated with ACM.

"� Group F, serving as the negative control, was not vaccinated, challenged or treated.

For all groups, researchers determined the colonization of the digestive tract, the presence of Se in feces and body weight 2, 7 and 12 days post-challenge.

Se and Coccidiosis: A Costly Pair

Increasing the numbers of salmonellae in the bird's cecum "the pouch where the large intestine begins "in the presence of coccidial infection may alter the normal cecal microflora, which are the bacteria and other microorganisms that typically inhabit the intestine.

This in turn may reduce the production of volatile fatty acids, which protect against Salmonella colonization in the cecum. (And the coccidial organism E. tenella itself may also reduce volatile fatty acid production.)

Moreover, E. tenella infection may cause damage to the surface of the cecal mucosa, making birds more susceptible to transmission of Salmonella from one bird to another, or from vectors like feces, personnel, feed, equipment and/or rodents.

Reduced Se Counts

"The Se count in the feces and cecal colonization were reduced in all three ACM-treated groups, mainly those receiving ACM by spraying and intraesophageal inoculation," Andreatti Filho reports.

An increase in cecal colonization and fecal excretion of Se was observed in the groups not receiving ACM, whether vaccinated or not vaccinated for coccidiosis, he adds.

"The cecum was the main site of colonization and persistence of Se," Andreatti Filho says. "ACM administered by spraying or intra-esophageal inoculation reduced Se in feces and the cecum compared to the group receiving ACM in drinking water."

With the exception of Group C, only Group F's protocol (the negative control) led to a significantly higher body weight compared to the other groups.

Encouraging Results

"No difference in body weight was observed between the groups not treated with ACM and challenged with Se and vaccinated or not vaccinated against coccidiosis, thus demonstrating that the vaccine had no negative influence on weight gain in chicks challenged with Se," Andreatti Filho says.

"Using competitive exclusion products like ACM, a number of researchers have shown that bacterial cecal microflora from adult birds can protect newly hatched chicks challenged with Salmonella."

In this case, Andreatti Filho explains, "competitive exclusion" means that Salmonella and other pathogens will probably be reduced if beneficial bacterial microflora arrive first and establish colonies in the ceca of broiler chicks. (Usually, competitive exclusion products are prepared from undefined ACM cultures, while probiotics are made from defined cultures containing one particular type of bacteria or a prescribed combination of different bacteria.)

"These are complex concepts because researchers still have some doubts about the mechanisms whereby beneficial bacterial microflora inhibit pathogens like Salmonellae," Andreatti Filho emphasizes.

"But it is already known that probiotics teamed with vaccines can help to reduce the use of veterinary pharmaceuticals in broilers. With proper protocols, these management tools promote good performance in broilers, while also reducing Salmonellae."

The results of the work of Andreatti Filho and his colleagues were highlighted in a paper entitled "The effect of coccidiosis vaccine on Salmonella enteritidis colonization in broiler chicks inoculated with anaerobic cecal microflora," which was published in Arquivo Brasileiro de Medicina Veterinária e Zootecnia 51(4), August, 1999, 311-361.

Source: CocciForum Issue No.4, Schering-Plough Animal Health.