4. DISCUSSION
The overall individual prevalence and herd prevalence of GIP infection reported among agro-pastoral cattle herds in this study were 58.6% and 92.3%, respectively. The high GIP infection is a reflection of the extent of contamination of the grazing paddock or pasture with infective stages of these parasites (Fikru et al., 2006). This could be as a result of the traditional husbandry method used in rearing the cattle (Adejinmi and Harrison, 1997). Reports from different parts of Nigeria also showed the prevalence of GIP ranging from 34.9% to 82.24% (Afolabi et al., 2007; Pam et al., 2013; Sylvia et al., 2015; Okike-Osisiogu et al., 2016; Takeet et al., 2016; Abah and Ebong, 2017; Adelakun and Akande, 2018). High prevalence rates of GIP have also been reported from other countries including Colombian Northeastern Mountain (50.5%) (Pinilla León et al., 2019), Pakistan (64.6%) (Rafiullah et al., 2011) and Ghana (95.5%) (Squire et al., 2013). The prevalence reported in this study is an indication that GIP infection remains a threat to the livestock industry because of its ability to cause a reduction in weight gain, high morbidity and mortality especially in young animals (Diaz de Ramírez et al., 1998; Cordero and Rojas, 1999).
Notably, Eimeria spp was the only protozoan and most abundant GIP identified in this study. Contamination of water and pasture by excretion and secretion from infected cattle as well as poor pasture management (Tamasaukas et al., 2010) are factors that could contribute to the high prevalence. The parasitic abundance of Eimeria spp corroborates earlier finding from the study location where a prevalence of 40.1% was reported (Adelakun and Akande, 2018). In contrast, Karaye et al. (2018) reported a much lower prevalence of Eimeria spp in Plateau State. This study also negates previous reports by Raza et al. (2014) and Swarnakar et al. (2015) that coccidian oocysts were the least GIP observed. The variation in prevalence could be due to immunological status and management condition. Eimeria spp are known to cause coccidiosis primarily in calves and accompanying signs are diarrhoea, dehydration, weight loss, depression, loss of appetite and occasionally, death may also be observed in infected animals (Squire, 2013).
The nematodes recorded the highest prevalence of GI helminths, which agrees with other previous studies (Tshering and Dorji 2013; Adelakun and Akande, 2018). Death of livestock is common in the tropics where marginal levels of nutrition exacerbate the detrimental effects of infection (Ademola and Eloff, 2010). Most prevalent nematode identified in this study was Neoascaris vitulorum ; previous study by Raza et al. (2007) in Pakistan has also shown N. vitulorum to be the most frequently occurring nematode in cattle. The prevalence obtained in this study is similar to the 10.2% reported in Oyo State by Oluwole et al. (2016). Neoascaris vitulorum is a parasite of the small intestine of ruminants (Roberts, 1990). It is responsible for high morbidity and mortality rates in ruminants (Das and Singh, 1955; Patnaik and Pande, 1963) resulting in serious economic losses (Enyenihi, 1969).
Other nematodes identified include Strongyles spp,Nematodirus spp and Strongyloides spp. Schistosomaspp and Paramphistomum spp belong to the trematoda class and are both helminths of veterinary importance. They are responsible for schistosomosis and paramphistomosis, respectively. Schistosomaspp however, is of public health importance as the report of hybrid ofS. bovis and S. haematobium (Webster et al., 2013) are been reported in Africa. The prevalence observed could be as a result of the rainy season during which the study was carried out. This could have aided the viability of eggs, growth and development of both the infective stages of the parasites and the intermediate host, all of which are necessary for the successful completion of the parasite’s indirect life cycle (Colina et al., 2013).
Taenid spp and Monienza spp were the only two identified cestode species. The Taenid spp have zoonotic implication. Cattle are the known intermediate hosts while humans are the definitive hosts. However, in this study, we found eggs typical of Taenia, which suggests the need for further studies; particularly molecular characterization towards deciphering the true picture of things. Monienza spp is responsible for monieziasis which is often present in ruminants that graze on infected pastures and the infection is maintained by the availability of Oribatid mites (intermediate hosts) that are required for the completion of the lifecycle of Moniezia spp (Quiroz et al., 2011).
Generally, susceptibility to GIP infection might be influenced by varying factors such as age, breed, health status, pregnancy and history of early infection (Pfukenyi and Mukaratirwa, 2013). However, in this study, age, BCS, breed and herd size were the factors significantly associated with the prevalence of GIP. A relatively high GIP infection was observed in cattle <2years of age compared to the young and adult cattle. This age prevalence of GIP is similar to the findings of Tilak et al. (2016). The higher GIP infection in cattle less than 2 years could be because the older cattle, greater than 2years, are more resistant to GIP, while the cattle <2years are more susceptible to infection (Pfukenyi et al., 2007), being new and just coming to the pasture. Cattle with lean BCS had the highest GIP infection, a likely impact of GI parasites on the body mass of severely affected cattle. Insufficient fat reserves, poor health and nutritional factors are primary reasons why poorly conditioned animals are weak at mounting protective immunity against worm infestation (Tasawar et al., 2011). The White Fulani breed of cattle had the highest GIP infection, an outcome that corroborates previous studies in Adamawa State (Aliyara et al., 2012; Qadeer et al., 2015). This may simply be because it was the predominant breed sampled. Finally, cattle from herd size that were grouped into 1-30 had GIP prevalence higher than other groups of 31–50 cattle and the greater than 50. The association of herd size to GIP prevalence might be as a result of the immunological status of the animals, difference in the grazing area and management conditions (Regassa et al., 2006).