Source: PoultryHealthToday.com
Bioshuttle programs are a valuable tool for managing coccidiosis, according to Greg Mathis, PhD, Southern Poultry Research.
Coccidiosis remains among the costliest of diseases for broiler producers. It is controlled with either anticoccidials, vaccination or a combination of the two. However, concern about anticoccidial resistance and the advent of no antibiotics ever (NAE) production — which prohibits the use of antibiotic anticoccidials — have initiated a shift toward vaccination for managing coccidiosis, Mathis explained.
A bioshuttle program involves a combination of vaccination and anticoccidials. Chicks receive a coccidiosis vaccine at the hatchery, then an in-feed anticoccidial is administered.
Coccidiosis vaccines today are all comprised of live Eimeria, which stimulate immunity by providing controlled exposure to coccidia and coccidial cycling. With each cycle, immunity strengthens, but live coccidia still naturally cause some damage to the intestinal tract, he said.
The timing of anticoccidial administration after vaccination varies but is generally implemented about the time birds start receiving their grower ration. By delaying administration of the anticoccidial, immunity from vaccination is allowed to develop normally, then the anticoccidial reduces the coccidial infection level, Mathis said.
The reduction in infection improves feed utilization and minimizes the spread of coccidia to birds that might have been missed during coccidiosis vaccination, he said.
Necrotic enteritis
Some producers have gained enough experience with vaccines to achieve control of coccidiosis without adding an anticoccidial to the protocol. “Certainly by 28 and 35 days – if everything was applied correctly – you shouldn’t have any problem with immunity development,” Mathis said.
One problem that can arise with vaccination alone, however, is necrotic enteritis (NE), which often follows coccidial cycling. Early cycling leads to an increase in coccidiosis until immunity is adequate enough to reduce infection. This is particularly so for coccidial cycling initiated by coccidiosis vaccination. Using an in-feed anticoccidial after vaccination lowers peak cycling of the Eimeria, although anticoccidials should not be administered so soon they kill off the vaccinal coccidia that initiates immunity, he said.
Eimeria maxima, which is contained in all coccidia vaccines and is the species most often associated with NE, develops deep in the gastrointestinal tissue. Damaged cells are released and mucus production increases; both provide feed for the bacterium clostridium. This in turn leads to exponential clostridium reproduction, toxin production and NE. A bioshuttle program reduces the chances of NE development by keeping E. maxima at a lower level.
NAE programs
Since ionophores are considered to be antibiotics by FDA, they can’t be used in NAE systems. Instead, non-ionophore anticoccidials are used following vaccination. However, some NAE producers with coccidiosis problems despite the use of anticoccidials or antibiotic alternatives are returning to the use of ionophores, Mathis continued, and therefore are no longer producing NAE poultry.
In his opinion, anticoccidial drugs including Ionophores generally have stronger efficacy than alternative products.
Although most non-ionophore anticoccidials kill off coccidia, an exception is zoalene, which Mathis said is especially beneficial. Even though it is not an ionophore, it allows for some coccidial “leakage” like ionophores do and that further initiates immunity.
“Due to limited feeding duration, low resistance selection pressure and introduction of new coccidia with each round of vaccination, resistance development against zoalene in a bioshuttle program will be slow,” Mathis predicted.
Tips for success
Success with a bioshuttle program requires proper storage and administration of coccidiosis vaccines, he emphasized. It also depends on good chick quality, adequate feed and water as well as proper brooding and litter management.
If NE is a problem, producers need to pinpoint when it occurs and factor that into the design of their bioshuttle program, Mathis said. If administered early, this could help prevent NE but will impair coccidial immunity. In this case, he suggests that the anticoccidial used be feed longer so that coccidiosis control is even throughout growout.
If a producer routinely has NE issues later during production, then the initiation of the anticoccidial in a bioshuttle program can be started later. This allows for unhampered immunity development initiated by vaccination, then control of coccidial infection with the anticoccidial.
The bottom line is that reducing the effects of vaccine-related coccidiosis with a bioshuttle program can improve performance as well as potentially reduce the development of NE, Mathis concluded.
