1. INTRODUCTION
The livestock production sector in Nigeria contributes immensely to the economic well-being of the nation and over 80% of the population are in a way involved in agriculture (Otuma and Udenwa, 2009). Cattle production contributes 50% of the total meat supplied by the livestock industry in Nigeria (Adedipe et al., 1996). The cattle population in Nigeria has been estimated to be 15.3 million (Umar, 2007; Umar et al., 2008; Tibi and Aphunu, 2010) with 80% of this managed by the pastoralists (Okoli et al., 2012) who practice extensive production system which is the traditional method of grazing cattle in Africa (Kanyari et al., 2009). Breeds of cattle indigenous to Nigeria are the White Fulani, Red Bororo, Sokoto Gudali (Bokolo), Adamawa Gudali, Wadara, Azawak, Muturu, Keteku, Ndama and Kuri (Pagot, 1992; Babayemi et al., 2014). However, the popular breeds of cattle in southwestern Nigeria are mainly White Fulani and the Bokolo breeds.
Gastrointestinal parasitism is mainly caused by helminths and protozoa (Williams and Loyacano, 2012). Three major classes of helminths that are of veterinary importance often affect the gastrointestinal tract of cattle. They include the nematodes (e.g. Nematodiru s sp ,Ascaris sp , Strogyloides sp), trematodes (e.g.Paraphistomum sp, Schistosomum sp ) and cestode (e.g.Monienzia sp ) (Onaga et al., 2009). Geoclimatic conditions and a poor GIP awareness by livestock farmers contribute towards a conducive environment for the development and growth of parasites (Raza et al., 2007). Some gastrointestinal parasites (GIP) of cattle likeShistosomum sp and Fasciola sp have potentials of infecting humans (Oslo and Guselle, 2000) and the increasing resistance of GIP to several anti-helminthics (Jackson and Coop, 2000; Albonico, 2003; Albonico et al., 2004) are major challenges that require swift solutions. Notably, the increasing gastrointestinal helminth infections in cattle due to continuous re-infection from persistent exposures to infected grazing lands has a way of aggravating the challenge of helminths’ resistance to dewormers.
The traditional method of grazing cattle in Nigeria predisposes them to ingest infective stages of GIP during grazing and/or use of communal water sources. Of the three gastrointestinal helminths classes of veterinary importance, the nematodes are responsible for the most economically devastating effect of livestock in Nigeria (Afolabi et al., 2017). This is aided when grazing animals ingest infective larvae from the pasture, the larva develops into adult parasites in their host and lays eggs, which are excreted in the ruminant faeces. The life cycle continues when the eggs hatch and larvae develop on pasture, where they can be ingested by grazing ruminants (Blackburn et al., 2011). The trematodes are equally important but will only thrive amidst intermediate host and in areas with poorly drained pastures and stagnant water. Cestodes, on the other hand, have less impact on cattle performance when compared with nematodes and trematodes (Shane et al., 2015). The typical lifecycle is also indirect, requiring one or more intermediate host. Gastrointestinal parasites, a major constraint to cattle production, are found within the gastrointestinal tract (GIT) of the animals (Oluwafemi, 2008). They constitute an impediment to efficient and profitable livestock production (Joachim et al.,2001). Gastrointestinal parasites might cause a wide range of health problems ranging from subclinical disease to actual death, depending primarily on the parasitic load and the general health of the animal (Schutz et al., 2012). Importantly, impaired reproductive performance has also been demonstrated because of the parasite burden (Forbes et al., 2004; Szyszka et al., 2013). Further, gastrointestinal parasites generate increased losses of endogenous protein, which might be a potential cause of the reduced weight gain in infected cattle (Kyriazakis et al., 1998).
Although studies have been conducted on GIP of cattle in various localities in Nigeria (Pam et al 2013; Sylvia et al., 2015; Okike-Osisiogu et al., 2016; Takeet et al., 2016; Abah and Ebong, 2017; Afolabi et al., 2017; Adelakun and Akande, 2018), little information is available regarding the gastrointestinal parasitic infections in Ibarapa Central and North Local Government Areas (LGAs) in Oyo State. This study area provides good arable land for pasture, which is attractive to pastoralists and farmers, which are the primary inhabitants of the area. The study was designed to investigate and provide additional information on the prevalence, distribution and factors associated with gastrointestinal parasites in agro-pastoral cattle herds in Ibarapa Central and North LGAs of Oyo State, Nigeria.