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CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Cattle constitute an important source of animal protein to many Nigerians. A lot of socio-economic importance is therefore attached to ownership of these animals that, in some cases, may be the only realizable wealth of a rural household (Omeke, 1988).

The world’s total numbers of cattle were 861.9 and 1078.2 million, respectively, i.e. there is about one goat to approximately 1.25 specimen 1 of cattle (FAOSTAT, 2008). In Nigeria, the total numbers of cattle were 53.8 and 33.9 million, respectively (FAOSTAT, 2008). This constitutes 6.2% and 3.1% of the world total population of cattle respectively (FAOSTAT, 2008).

Cattle harbour a variety of gastrointestinal tract (GIT) parasites, many of which are shared by many species. Among these parasites, helminths such as nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes) are the most important as they affect the growth as well as the production of the animals. Gastrointestinal nematodes of the Trichostrongylidae family are perhaps the most important parasites of cattle world-wide, causing significant morbidity and loss of production (Bagley, 1997; Pawel et al., 2004).

Gastrointestinal nematodes of cattle are roundworms parasitizing the abomasum, small intestine and large intestine. Infection usually occurs primarily through contaminated feed and water, enhanced by poor hygiene (Gatongi, 1996).

Intestinal helminthosis has for many years been recognized as a major problem in livestock rearing (Barger, 1997). Most specimen 2 of cattle infected have been shown to be asymptomatic or produce only mild symptoms, as a result of which infections are often overlooked till serious complication or chronic clinical signs occur (Rausch and Jentoft, 2002).

Gastrointestinal nematodes could be harmful to the infected animals and cause economic loss due to mortalities and reduced weight gain (Menkir et al., 2007; Vlassoff et al., 2001). Gastrointestinal nematodes also cause hypoproteinemia, impaired digestive efficiency and pathogenic complications such as anaemia, diarrhoea, oedema and recumbency which will lead to lowered productivity, retarded growth rate and even death of lambs (Holmes, 1986; Sykes, 1994; Forse, 1999; AlShaibani et al., 2009). The loss through reduced productivity is related to reduction of food intake, stunted growth, reduced work capacity, cost of treatment and control of helminthosis (Pedreira et al., 2006; Odoie et al., 2007; Chaudhary et al., 2007).

The severity of infections depends on the genera of helminth parasites involved, animal species, the number of infective stages on pasture, an alteration in host susceptibility, the introduction of susceptible stock into an infected environment,  the introduction of infections into an environment, ineffective parasite removal from the host animals due to poor drug administration techniques, and local environmental conditions such as humidity, temperature, rainfall, vegetation and management practices (Fakae, 1990a; Hansen and Perry, 1994; Sykes, 1994; Nwosu et al., 1996 a,b; Urquhart et al., 1996).

Several studies carried out on gastrointestinal helminthosis of cattle in many African countries showed that the prevalence of the infections varies from place to place. Studies on seasonal incidence of GI helminthosis are carried out to find the time in which infection with infective larvae begins, rises to a peak and decline so that the treatment can be timed to prevent severe infection as well as reduce contamination of pastures with eggs and larvae.  Comprehensive studies are required to know the level of GIT helminths in cattle in Benin, Northern Nigeria and factors contributing to their prevalence.

1.2        Statement of Research Problems

Gastrointestinal trichostrongyles of which Haemonchus contortus ranks highest in importance globally (Perry et al., 2002; Tariq et al., 2010) are recognized as a major constraint to both small and large-scale small ruminant production in developing countries, leading to significant economic losses (Martinez-Gonzalez et al., 1998). These nematodes (Haemonchus, Trichostrongylus and Cooperia) cause impaired digestion and also affect the absorption of minerals particularly calcium and phosphorus (Speedy, 1992). 

Surveys indicated that up to 95% of cattle in the tropics are infected with helminths with Haemonchus and Trichostrongylus being the main genera involved (Rey, 1991). Mortality rates in herds may exceed 40% while weight losses of up to 6-12 kg/year/animal may occur (IEMVT, 1980).

In Nigeria, the economic loss due to helminthosis in cattle alone has been estimated to be at least 144 million naira annually, through death, weight loss and liver condemnation (Akerejola et al., 1979).

Fabiyi (1970) carried out a survey on the incidence of goat helminth parasites in Benin area of Nigeria. The result revealed the presence of 12 species of nematodes, 4 cestodes, and 4 trematodes with various percentages. Ajanusi and Chiezey (2005) also carried out a study on prevalence of Haemonchus contortus, Anaplasma ovis and Theileria ovis infections in specimen 2 of cattle in Benin and obtained a prevalence of 89.1%, 9.2% and 3% respectively. These reports indicate a high prevalence of gastrointestinal parasitism in specimen 2 of cattle which may be contributing to low productivity of these animals. 

Fabiyi‟s survey was done over three decades ago. Besides, the studies of Fabiyi (1970) and Ajanusi and Chiezey (2005) were restricted to goat helminths. There is therefore a need to conduct a more comprehensive survey on prevalence of gastrointestinal helminths of cattle in Benin, Northern Nigeria. Information that will be generated from the studies can contribute to the understanding of the epidemiology of helminth infections in the area of study for proper control measures.

1.3         Significance of the Study

In Nigeria, gastro-intestinal nematode parasitic infection is one of the major health problems. Gillian et al. (2004) reported that nematode infections affect the health of millions of people and animals, causing huge economic loss in livestock farming. Previously, Mulugeta et al. (1989) reported that infection is enormous in small domestic ruminants, causing major production loss.

The animal protein intake in Nigeria is 3.24 g/day falls far below the FAO recommended value of 34g per day (Shaib et al., 1997).  Since cattle contribute an estimated 35% of the total meat supply in Nigeria (Brinkmann and Adu, 1977; Adu and Ngere, 1979), efforts at increasing the protein intake should partly be directed at steps aimed at increasing livestock production (Jibril et al., 2010). Besides, an increase in livestock production will translate into an improve in livelihood of the populace since a number of people are involved in the livestock industry (maintenance, transportation, slaughtering and trading) (Jibril et al., 2010).

There is dearth of information in Benin as regards the overall prevalence of GI parasite infections of cattle and the relationship between actual worm burden, faecal egg counts, and PCV. Studies carried out by Fabiyi (1970) in Benin on specimen 2 of cattle  need to be revalidated as a result of tremendous changes in the climate and husbandry practices of livestock in Benin The present study is therefore aimed at determining the current status of GI helminth infections of cattle slaughtered in New Benin Market slaughter slab in Benin, Northern Nigeria. The knowledge of the relationship between faecal egg counts, actual worm burden and PCV will provide useful information for Veterinarians. The research work will also provide baseline data on burdens of gastrointestinal helminth infections in specimen 1 of cattle and goat which can be useful for comparison with data from other climatic areas. The information will also be of value in control measures of helminthosis in Benin.

1.4        Aim of the Study

The aim of the study is to evaluate the current status of GIT helminth infections of cattle in Benin, Nigeria.

1.5   Specific Objectives

Specific objectives were:

1.     To determine and compare the distribution of GIT helminths of small ruminant slaughtered in New Benin Market slaughter slab in Benin by species, age, sex of the host and season of the year. 

2.     To determine the faecal egg counts of GI helminths in cattle meant to be slaughtered in New Benin Market slaughter slab in Benin

3.     To determine the relationship between worm burden, faecal egg counts and PCV of cattle slaughtered in New Benin Market slaughter slab in Benin

4.     To determine the prevalence and seasonal occurrence of arrested L4 larvae of Haemonchus contortus in abomasums of cattle slaughtered in New Benin Market slaughter slab in Benin

1.6          Research Questions

The following research questions have been formulated to guide the study.

1.       What adult helminth parasites are present in GIT of cattle?

2.       Is the distribution of GIT helminths in cattle affected by the season of the year or species, age and sex of the host? 

3.       Is there correlation between adult worm burden, faecal egg counts and PCV in cattle?

4.       At what month(s) of the year do larvae of Haemonchus contortus go into hypobiosis in cattle?

1.7       Scope and Limitation of the Study

This study was restricted to cattle slaughtered in New Benin Market slaughter Slab in Benin, Northern Nigeria. Liver and lung were not collected during the study as a result of financial constraint. Adult female and male species of helminth parasites encountered during the survey were not counted separately but were only noted. Faecal samples were not cultured for L3 identification of nematode species eggs since adult worm nematodes were identified to generic level.

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