The overall approach was pivotal during Hebra and Trouw’s Coccidiosis Prevention Day on September 15 and at the symposium “Using coccidiostats or alternative strategies: Hard Choices” presented by Schothorst Feed Research on October 13. Intestinal infections associated with diseases were also discussed there.
Coccidiosis has been around for a long time
The single-celled parasites that cause coccidiosis have likely been around for as long as poultry have been around. The parasite is almost impossible to eradicate because it produces eggs that are encapsulated: ova.
There are huge numbers of these materials that are highly resistant to cleaning agents and disinfectants. It is almost impossible to get them out of the barn or environment. Until the beginning of the last century, eimerias caused minor damage.
Animals need more than energy, protein, minerals and vitamins
However, poultry has been bred commercially since 1918 with about 250 heads on one hectare of lawns with night pens. The country is becoming increasingly infected with coccidiosis eggs which can cause major problems. Since then, coccidiosis has not left poultry.
Seven syndromes of coccidiosis
There are seven clinical pictures of coccidiosis, because there are seven different types of algae known in poultry, according to a report by poultry veterinarian Christian Ter Veen of Royal GD. In ordinary broilers, Eimeria (abbreviated as E.) acervulina, E. maxima and E. tenella are of particular interest.
E. acervulina causes some growth retardation, but it does not often make flocks sick. Sometimes to thin the compost and bulbs. E.maxima occurs from the third to fifth week. Usually there is no clinical disease, but developmental delay and dyspepsia.
In severe cases, E. maxima can cause gastrointestinal bleeding, leading to animal weight loss, pallor, enlarged plumage and sometimes death. From the fourth week, all poultry can be affected by E. tenella. This species is more common in slow-growing chicks, but also in ordinary chicks. This can lead to appendicitis with symptoms similar to a serious E. maxima infection.
E. brunetti is usually not found in ordinary broilers, but it does occur in poultry from six weeks of age and sometimes in slow-growing chicks. The disease is usually mild and the animals have diarrhoea. E. necatrix occasionally occurs in slow-growing or organic chicks, and more often in broilers of nine to fourteen weeks of age. Animals lose weight and have watery, bloody, and sometimes slimy dung. Leakage can be as high as 25 percent.
Although coccidiosis is a disease that affects mainly young chickens, it can also occur when reaching the laying farm. E. praecox and E. mitis cause stunted growth. E. mitis occasionally occurs in broilers. E. praecox is rare.
In addition to direct damage from coccidiosis, the parasite also causes indirect damage. Intestinal damage can cause dysbacteriosis or bacterial enteritis. The composition of the microbiota in the intestine becomes unstable, and unfavorable microflora prevails.
The digestion of nutrients deteriorates and with it the conversion of feed. Diarrhea can result. Moreover, the ever-growing Clostridium perfringens bacteria can multiply and cause necrotizing enteritis: the death of parts of the intestine. The result is more stunted growth, poor feed conversion and loss.
According to veterinarian Martin de Gussim of VetWorks, it is important to know how much damage coccidiosis itself and/or bacterial enteritis can cause. On average, the harm for a 2.5 kg broiler is 10 cents due to coccidiosis and 10 cents due to bacterial enteritis. More concentration is possible by analogy. If the expected damage from bacterial enteritis is less than a dime a dozen, the approach will focus primarily on coccidiosis or vice versa.
The economic and health damages of coccidiosis make it necessary to treat the parasite. This has been happening for decades with coccidiostats. These are chemical agents that intervene at different stages of the life cycle or with ionophores.
These alter the metabolism of the unicellular parasite, causing it to break down. No new crocidistats have been developed in recent years. What is clear is that the eimeria parasite becomes resistant to ionic carriers and chemical agents. That’s why vaccination will play a more important role, says vet Joanne Molest of Hebra.
Coccidiosis vaccines use highly attenuated strains of the Eimeria parasite, which are highly sensitive to anticoccidial agents. Those weak breeds breed in broiler chickens or chickens that build immunity at an early age. Chickens do not suffer much from weak parasites, according to Mollist, the results are comparable with the use of coccidiostats.
According to De Gussem, it is important to choose a vaccine that contains the species also present on the farm. ‘It is possible to have the vaccination alternate with coccidiostats. By vaccinating several successive rounds, the weakened vaccine strains gained the upper hand and the coccidiostats worked better than before.
Molest prefers to vaccinate three consecutive rounds. Since there is always some virulent Eimeria left, there is an option to use coccidiostat for three rounds and then vaccinate again for three rounds. Of course, broiler farmers can completely switch to vaccination.
Can this be done without coccidiosis and vaccinations?
Treating coccidiosis without getting coccidiosis or vaccinating has proven to be difficult, says broiler specialist Bert Jansen at Trouw Nutrition. Adding acids, for example, to feed can have a positive effect on the composition of the intestinal microflora and the health of the intestine, but not on the eimeria parasite. Active substances from plants, phytogens, seem to prevent coccidiosis, but lead to a significant increase in feed costs.
Veterinarian and botanical researcher Maria Grote of Wageningen Food Safety & Research has several studies on the active ingredients. Unfortunately, these are generally not well comparable and their effects are not well documented. They sure can work.
The effect is shown, for example, by a study with saponins. These are soap-like substances that are extracted from the Yucca Plus plant.
“Effects on growth, feed conversion and the number of saponins-containing eggs are comparable with the use of coccidiostats,” Groot explains. You should not underestimate the effect of active substances from plants. Animals need more than energy, protein, minerals, and vitamins. In nature they search for this supplement themselves. We have to make sure it’s in the feed.
Medium chain fatty acid and other measures in the feed are important for support. Certainly with vaccination, researcher Eileen van Erden of Shuthurst Feed Research showed. Vaccination worked best with a combination of supportive dietary measures. It turned out that the animals performed better.
Researcher Kari Ljøkjel says that in Norway, coccidiosis is well controlled through vaccination and feeding procedures. The use of coccidiostats in broilers has been voluntarily banned in this Scandinavian country since 2016. Poultry farmers switched to vaccinations and worked for two weeks between flocks.
In addition, the chicks receive support especially in the start-up, among other things, butyric acid, antioxidants and probiotics in the feed. Formic acid follows thereafter from the seventh day. With this strategy it was only possible to process 0.1% of the flocks.