Identification of the main intestinal helminths of local breed chickens (Gallus gallus domesticus Linnaeus, 1758) reared in traditional mode in the Oran region

Almost 90 % of poultry in developing countries are raised under the extensive system. Local poultry genotypes represent 80 to 99 % of the total numbers of poultry populations present in rural areas (Sonaiya et Swan, 2004). The extensive livestock system is essentially based on traditional farming methods that are not very demanding and that are suitable for village and even urban and peri-urban environments in several African and Asian countries. It is a breeding which is left to itself, generally in the hands of women, the average number of each farm is between 15 and 20 subjects, the hens are fed by rye, Criblure, oats, and kitchen scraps. They are raised in freedom and supplement their diet around the farm (Belaid, 1986). This is the case for the breeding of local poultry in the Oran regions which are located in rural areas. There are usually chickens, roosters, ducks, geese and turkeys. Backyard chicken is the most common type of farming in these rural areas, being generally affordable for poor rural households. This type of farming contributes significantly to the consumption of animal protein in rural communities in the form of meat and eggs (Mahammi, 2015) and therefore contributes to a balanced and nutritious diet (Ahlers et al., 2009; Mouhous et al., 2012). Traditional poultry farming remains marginalized and practiced mainly in small-scale farming by women in rural areas (Moula et al., 2009).

However, when it comes to chicken production, one of the major constraints is sanitary (Chrysostome et al., 1995). Indeed, many diseases of various origins (parasitic, bacterial, viral) affect local chickens and constitute a real scourge which slows down the development of this breeding. Among these diseases, chicken digestive parasitism, which is defined by the presence of parasites in different parts of the digestive tract, from the oral cavity to the cloaca, is a fairly common pathology. The main parasitic diseases linked to this parasitism in chickens are Helminthiasis, which are due to the presence and development in the digestive tract of chickens of pathogenic worms belonging to the classes of Nematodes, followed by Cestodes (Bindoula, 1989) and more rarely Trematodes. (Cribb & O’Callaghan, 1992). Acanthocephali are exceptional in chickens (Reid & Mc Dougald, 1978). The reported prevalence of helminth species varied among species and ranged from 30 to 100 % (Shifaw et al., 2021).

The parasitic species of helminths in the digestive tract are very common. They have a significant economic impact and can cause a significant decrease in productivity (growth retardation, reduction in laying). They promote the spread of deadly infectious diseases and reduce the effectiveness of the immune system, which is ultimately depleted in the long term.

The objective of this study is twofold:

- Search and identify endoparasites in the digestive tract after autopsy of local breed chickens reared in traditional extensive mode in the Oran regions;

- Evaluate the rate of infestation of groups of helminths and the prevalence of each species of helminth.

Animal-related research has complied with all national regulations and institutional policies relevant to the care and use of animals as approved by the ethics committee of the University of Oran 1 under reference 02 / CE / UO1 / 2021

The present study made it possible to identify within our sample composed of 10 local breed chickens (Gallus gallus domesticus) two species of nematodes and two species of cestodes.

The prevalence of parasites of the gastrointestinal tract observed in domestic chickens in this study ranged from 10 to 20 % for cestodes and 50 to 60 % for nematodes. These prevalences are much lower than the 90 % recorded by Fabiyi (1972), 92 % by Gadzama and Strivastava (1986), 100 % by Okon and Enyenihi (1980) and 95.2 % by Fatihu et al. (1991). This decrease in overall prevalence would be linked to the general improvement in health habits, which makes the environment less favorable to parasites and their intermediate hosts.

According to Bush et al. (1997), species with a prevalence <30 % are considered as rare species, those with a prevalence > 30 % as common; those with a prevalence > 50 % as the most widespread. According to the values obtained (Fig. 6), Heterakis gallinarum (60 %) is the most widespread species followed by Ascaridia galli (50 %). The other species can be considered rare, in particular Raillietina tetragona (10 %).

The dominance of Heterakis gallinarum is reported in several works. The total prevalence of gastrointestinal parasites in indigenous chicken in Kashmir has been estimated at 40.14 % (Raza et al., 2016). In particular, 2 species of nematodes were recovered during the study include Ascaridia galli and Heterakis gallinarum with a prevalence of (39.53 %) and (41.86 %) respectively (Raza et al., 2016). Shifaw et al, (2021) and according to a meta-analysis instead showed a high prevalence in favor of Ascaridia galli (35.9 %), followed by Heterakis gallinarum (28.5 %). Likewise, Zada et al. (2015) showed a relatively low overall prevalence rate of A. galli by about 21.44 %, however A. galli was the most common and prevalent nematode in chickens in Mardan district of Pakistan. The study also showed that A. galli is a common health problem in free-range chickens and poultry (Zada et al., 2015).

The study carried out by Yousfi (2012) in the Oran region on local chicken also showed a massive infestation of Heterakis gallinarum and Ascaridia galli in the digestive tract.

The high rate of infection with Heterakis gallinarum and Ascaridia galli in this study may be influenced by many factors such as the accumulation of infective stages of larvae or eggs in the environment, the presence of intermediate hosts, the individual susceptibility of the final host (Magwisha et al., 2002), and the climatic conditions such as Temperature and humidity which promotes larval development and facilitates transmission (Kennedy, 1975; Audu et al., 2004; Magwisha et al., 2002; Dube et al., 2010; Ola-Fadunsin et al., 2019).

According to Andres et al. (1998), the establishment of Ascaridia galli in the gut is influenced by many factors such as the age of the chicken, the age of the infected eggs, the sex of the chickens and the diet of the host. Infection with this parasite leads to weight loss in chickens, which correlates with an increased parasite load. In general, impacts associated with nematode infections include reduced health, welfare and production performance due to reduced feed conversion ratio, reduced growth rates or weight loss, reduced egg production and egg quality, intestinal damage, and in severe cases, death (Phiri et al., 2007; Sreedevi et al., 2016; Rufai & Jato, 2017). Nematode infections can have direct adverse effects on the host, inducing the breakdown of the gastrointestinal barrier, but indirect damage can also occur via increased susceptibility to secondary infectious diseases (Dube et al., 2010; Sharma et al., 2019) and reduced host immune response (Pleidrup et al., 2014; Dalgaard et al., 2015).

Otherwise, Pinckney et al. (2008) indicate that the parasite Heterakis gallinarum is not pathogenic in chickens, but can be used for transmission of Histomonas meleagridis, a protozoan that can cause severe liver damage in turkeys.

Infection by three species was found in 2 chickens, ie a rate of 20 %. Single infections accounted for 10 % of the total infection, while double infections accounted for 30 %.

The most common type of double infection was roundworms and Heterakis gallinarum, which accounted for 70 % of double infections. This result is in agreement with those of Permin et al., 1997; Abubakar and Garba 2000; Luka and Ndams 2007. The diversification of parasitic fauna in the digestive tract of local chickens in the Oran region seems to be linked to the extensive farming method. This allows the chickens to feed on food soiled with helminth eggs and also by insects which act as intermediate hosts.

The present study also showed the presence of cestodes in the digestive tract of local domestic chickens. We found that the prevalence of Raillietina cesticillus is very low (20 %) compared to that reported in the work of Hanan et al. (2005) in Sudan. Another study in Kashmir showed that infestation of chicken with Raillietina cesticillus was estimated at 22.50 % (Javid & Syed, 2013). Concerning Raillietina tetragona, its prevalence was weakly evaluated in our study at 10 %, at 14 % in Sudan (Somia & Musa, 2002) but relatively high in India (Raza et al., 2016) with a prevalence of 34.88 % and high (65 %) in Kashmir (Javid & Syed, 2013). In free-living birds, the presence of cestodes in the gastrointestinal tract may be due to the continued ingestion of droppings or infected intermediate hosts such as earthworms, grasshoppers, cockroaches and beetles which are easily accessible in poorly managed stocks as suggested by Majaro (1993). Cestode infection in poultry is known to cause retarded growth, diarrhea, enteritis, haemorrhages and hypovitaminosis B. In addition to these deleterious effects, heavy infections may also lead to mortality in young birds and lowering or loss of egg production in laying chickens (Layers) (Javid & Syed, 2013).

The results obtained show that chickens of the local Gallus gallus domesticus breed in the Oran region are heavily infested by parasites including Heterakis gallinarum, the predominant species. Other species such as Ascaridia galli and R. tetragona responsible for economic losses are also present. The high prevalence rate of these parasites could be a silent source of economic loss for this type of traditional farming. The current study indicates that free range chickens are considered as potential reservoirs for nematode and cestode. This study therefore suggests the need to improve extensive farming conditions in terms of habitat, feeding and periodic pest control which will maximize profits and provide healthy birds for human consumption.