Coccidiosis in broiler flocks can be tackled by administering anti-coccidials. However, resistant coccidiosis can render coccidiostats almost useless. That was the case at Tom Serraerens broiler farm in Belgium. Using a vaccine was his last resort.
By Fabian Brockötter
From the time that poultry farmer Tom Serraerens bought his broiler farm in 2007 in Nevele, near the Belgian city of Ghent he knew that the situation in his three barns wasn’t perfect. The situation he encountered was far different from that on two other farms where he was raising broilers. “Intestinal health has been a problem from the start. Every round, I saw the same issues return. Mortality was higher than normal, birds weren’t growing as they should and litter quality was poor and too wet.” It didn’t take the veteran poultry farmer long to figure out that a coccidiosis infection was at the core of his problems. However the solution wasn’t as simple as he thought. Serraerens: “The coccidiosis infection in all three barns in Nevele was pretty severe. We did a chemical clean up and started administering anti-coccidials of different types in rotation programs in the hope that we could tackle the problem.”
Unfortunately the situation didn’t improve too much, at least not for a prolonged period of time. Poultry farmer Serraerens then asked the help of Maarten De Gussem, veterinarian with Vetworks. “We found extreme counts of oocysts, which showed resistance to all coccidiostats’’, De Gussem stated. The veterinarian and the farmer dug deeper into the history of the farm and spoke to former business contacts of the previous owner. With the information advisors, veterinarians and feed mills gave them, they eventually found the cause of the severe coccidioses infection.
De Gussem: “The previous owner was very focused on the lowest possible feed prices. To get the best price, he changed feed mills more than once per year. By doing so, prophylactic anti-coccidial programs were crossed time and time again. All common sense that should be in an anti-cox program, with rotation and/or shuttle schedules went overboard, just to get the best feed price proposition. In the end, the former owner went through every possible coccidiostat and ended up with a barn full of multi-resistant and very aggressive parasites.”
In conjunction with Serraerens, veterinarian De Gussem decided that the only option for this particular farm would be vaccination. “With vaccination, the introduction of a safe vaccine strain of coccidioses, we can push out the resistant field strains,” De Gussem said. Serraerens farm was the first Belgian farm to use the Hipracox vaccine, a live attenuated vaccine against coccidiosis in broilers. This vaccine is sprayed on the chicks, shortly after the one day old birds arrive from the hatchery.
It gives active immunisation to the chicks against Eimeria acervulina, maxima, mitis, praecox and tenella. The protection starts 14-21 days after vaccination and lasts until the end of the production cycle. De Gussem: “By vaccinating three consecutive rounds of chicks we were able to get the barn infection under control. There still is some scientific discussion over how the vaccination works. Some think the vaccine-strains will push out field strains because the broilers are infected with the vaccine-strains at day one and start to excrete vaccine oocytes two weeks later after a full lifecycle of the protozoa. Others think the field strains will crossbreed with vaccine strains, making the ‘end product’ (partly the old field strain) again sensible for anti-coccidials. This happens because the vaccine strains were selected on their sensitivity on coccidiostats. Of course, the end result is the same.”
Veterinarian De Gussem explains there is more to do than just administer a vaccine. “After a few rounds of vaccination without the use of anti-coccidials we have strains in the barn that are susceptible again for regular coccidiostats so we were able again to introduce a regular treatment program. But one has to take into account that everything is tailor-made for this situation.” Besides the vaccine, farmer Serraerens had to sharpen his management skills. “One has to stay on top of things,” Serraerens looks back. He invested in new drinking lines and adapted his ventilation and heating scheme to an optimum. Serraerens: “You need to stay sharp, keep a close eye on water, feed, litter management and climate. Besides that we monitor the flock very closely. The veterinarian visits the farm every week, every time picking birds from the flock and opening them up to look at their intestines.”
De Gussem: “One tends to look at the birds that are not performing optimal, but to get a good idea of what is going on in the flock you should open up seemingly healthy birds too. The different species of Eimeria cause lesions in different places in the intestinal tract, so you have to inspect the upper as well as the lower intestines. The most important advise I give to all my veterinarian colleagues is to open up the birds in broad daylight. Lesion scores 1 and 2 (white spots as small as pin pricks) are nearly impossible to detect under artificial lighting or in cloudy conditions outside.” According to the veterinarian you can only act on things you see, so taking the little extra effort to look at the birds outside of the house is pretty important.
After the coccidiosis vaccination, the farmer and veterinarian have to stay focused on bacterial enteritis. The vaccination doesn’t cause more problems, but earlier problems. Management of litter, ventilation and the need of acids, probiotics or even antibiotics needs to be monitored by the expert veterinarian as early as from day 10. Experience in Belgium and The Netherlands has taught that after vaccination there is less gut-health related antibiotic use, but treatments start earlier than normal. Treatment of the birds at a younger age leads to less kilograms of antibiotics needed, thus less expenses. Feed formulation is an extra management tool to keep on top of things. Between day 10 and 20 feed with less protein might be needed, depending on the severity of bacterial enteritis problems.
Of course the vaccination and the close monitoring by a veterinarian comes at a price. Serraerens is frank about this: “Looking at the extra costs before we started vaccinating last year I had some doubts. Looking back, it is a whole different story. The subclinical impact of coccidioses was far less and technical results improved greatly. My feed conversion rate came down from 1,38 to 1,25 and the flock is performing way better. Of the 90,000 animals I have on the Nevele farm, I earn €9,000 more per two months than in the old situation with all the coccidioses problems and secondary infections. That is worth the extra effort.” De Gussem: “After vaccination with the Hipracox vaccine we haven’t seen an outbreak of resistant coccidiosis for four consecutive rounds now and we didn’t have to resort to curative measures. Standard anti-cox treatment is sufficient.”