One of the biggest challenges in poultry production nowadays is to learn how to raise chickens without antibiotics and coccidiostats. This will automatically result in an increased need to rely on prevention strategies, especially Eimeria vaccines. But are Eimeria vaccines and antibiotic reduction incompatible or can they coexist?
What’s the real cost of Coccidiosis?
Coccidiosis caused by Eimeria parasites is one of the most common and widespread diseases in modern commercial poultry systems.
Nowadays coccidiostats are still widely used in broilers for the prevention of coccidiosis in chickens. On the other hand, 100% coccidiosis vaccination is not questioned in the case of breeders. But, why should we reject it in the case of broilers?And more importantly, is 100% coccidiosis control possible in broilers by means of a vaccine?
Without any doubt, the industry does question 100% coccidiosis vaccination in broilers.
So far, this 100% vaccination has been limited to some niche productions, such as free-range, organic and native/coloured chickens in the case of Asian countries. These productions have adopted vaccination against coccidiosis in a natural way, without any problems or any changes in the way of production.
The global cost of coccidiosis has been recently estimated to be >$3 billion per annum. This cost calculation is based on direct production losses and indirect costs for prevention measures. However, most of this financial loss comes from an increased feed conversion ratio (FCR) and decreased weight gain (Williams, 1999). In addition, clinical disease – in broilers mainly caused by Eimeria tenella – leads to increased mortality. Finally, Eimeria is also one of the most important predisposing factors for bacterial enteritis.
Anticoccidial feed additives or anticoccidial drugs have been and still are the most widely used prevention tool in broilers. These products have many merits but the two main issues associated with their use are (i) reduced sensitivity of Eimeria parasites when a certain product is used for too long or too often and (ii) cross resistance between certain compounds (Marien et al., 2007).
In the first part of this post, we saw that the joint administration of two vaccines for coccidiosis in chickens -EVALON® and HIPRACOX®- together with probiotics is feasible with a vaccination spray device that ensures accuracy and precision -Hipraspray® device-. In this second part, we assess the added protective effect of the synbiotic PoultryStar® in broilers vaccinated against coccidiosis with HIPRACOX® and challenged with a coccidia species mixture at day 15.
456 day-old male broilers of the ROSS 308 breed were housed for a 35-day grow-out in floor pens covered with wood shavings.
Ventilation and heating were regulated automatically. Pelleted feed and water were provided ad libitum.
The commercial feed contained neither antimicrobials nor anticoccidial additives. The animals were divided into 3 treatment groups of 152 animals with 8 replicates per group (see Table 1).
On several occasions in this blog, we have talked about coccidiosis diagnosis, and we recently focused on the lesion scoring technique, which is certainly the most widely used method for diagnosing Eimeria tenella in the field. Let us carry out a brief review of all the posts published on this subject with a view to understanding how to make the most of each technique.
Wrongfully because the presence of oocysts cannot be interpreted as an outbreak of coccidiosis, as Eimeria oocysts are ubiquitous.
Therefore, the significance of this finding must be weighed against the level of oocysts/gram first and then other indicators of disease, such as the presence of clinical signs in live animals, as well as macro- and microscopic lesions in the intestine at necropsy.
The need for prevention against this disease is as old as coccidiosis itself in poultry farming. It has been some time since the first vaccines were developed and fortunately innovations have been incorporated into the production process which have meant that prevention against Eimeria is now safer, more effective and longer-lasting.
The first vaccine against coccidiosis in poultry farming was developed in 1952.
At that time, the product contained only a single, non-attenuated species of Eimeria (Eimeria tenella). In 1974, Dr. Jeffers and his colleagues published their discovery of the precocious lines, thereby revealing the method of attenuation by precociousness.
However, for various reasons, the first vaccine containing Eimeria species attenuated by precociousness was not marketed until 1989 (Williams, 2002).
Avian coccidiosis is a costly intestinal disease caused by parasites of the Phylum Apicomplexa, genus Eimeria, which frequently affect poultry. Apart from the three best known Eimeria spp. (Eimeria acervulina, Eimeria maxima and Eimeria tenella), other species can also affect chickens, and their appearance is mostly related to the category of birds under consideration: long or short-lived birds. In this post we will review the most important posts published so far on this subject and we will try to shatter a myth: do Eimeria mivati and Eimeria hagani really exist?
Chickens are susceptible to seven Eimeria species: Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox and Eimeria tenella. Very often this is the start of many articles about coccidiosis, however many argue that another two species should be included in this list.
When we talk about coccidiosis in chickens, we should not forget to mention gut health, as whatever provokes a disruption of gut balance can also influence this disease or the other way around. In view of this strict interconnection and taking into account the fact that optimal gut health represents the basis for the ever-increasing need to reduce antibiotic & anticoccidial use, it is easy to understand that nowadays the “Silver Bullet” would be to find the perfect combination between coccidiosis vaccines & feed additives intended to maintain gut balance, such as probiotics. This combination should guarantee the best coccidiosis prevention through vaccines, together with optimal gut health and competitive productive results.
Before evaluating whether the combination of vaccines for coccidiosis in chickens plus probiotics is beneficial from the intestinal health point of view, we had to investigate the possibility of administering EVALON® and HIPRACOX® vaccines, each together with a different probiotic, using Hipraspray®.
When talking about the diagnosis of Eimeria in chickens, most people think of the oocyst count (OPG) and now PCR as the gold standard methods for obtaining the most accurate diagnosis. This is partly true, however it is very important to remember that the earliest diagnosis is still only possible with the classical lesion scoring technique implemented in 1970 by Johnson & Reid. Some factors can affect the lesion scoring method and should therefore be taken into consideration: proper selection of birds, careful necropsy procedure and accurate training for lesion identification.
Eimeria tenella is by far the most widely detected species on farms when routine lesion scoring is performed. However, it is well known that most of the time Eimeria infections are multiple. On the other hand, during last decade the egg sector has probably undergone the biggest changes, with an ever-increasing percentage of cage-free laying hens, especially in Europe.
Generally in layers and breeders we distinguish between caecal and intestinal coccidiosis. Caecal coccidiosis is due to Eimeria tenella that is confined to the caecum and consists of the presence of hemorrhages on the outside or inside of the wall of the caecum.
This acute infection occurs most commonly in young chicks and is by far the most widely diagnosed in the field due to its typical lesions and location. For this reason, a common belief is that Eimeria tenella is the most prevalent all over the globe. In fact, macroscopic lesions are amongst the most pathognomonic with blood or typical molds in the caecum and common findings of bloody droppings in the litter.