**7. Globally applicable gastrointestinal nematodes control measures/ strategies**

Control of gastrointestinal nematode parasite (GINP).

Numerous techniques and plans have been utilized to lower the gastrointestinal (GI) nematode parasites of small ruminants across the world. Some of the techniques and methods are appropriate, and a few of them have limitations. Moreover, new methods and new approaches are being evaluated and established. The prime methodologies that have been used routinely to reduce the burden of GI nematodes are reviewed here.

#### **7.1 Chemical control methods**

#### *7.1.1 Chemotherapy (anthelmintic)*

Anthelmintics are those drugs that kill the helminths and are playing a toxic role to the worms and can be achieved by exposing the nematodes to a higher concentration of anthelmintics. This higher concentration is for worms not for the host body cells. This higher concentration inhibits the vital metabolic processes of the worms and kills the worm either by starving it or paralyzing it [23]. Resistance is a reduction in the efficacy of certain anthelmintics against parasites that are susceptible to anthelmintics in normal conditions [41]. Chemotherapeutic application is a very common and primitive method (conventional) to control the GINP around the globe. The agents have been used for both therapy and prophylaxis. Benzimidazole, Ivermectin, and Imidathiazole are three major chemical groups that have been used frequently for decades.

Several reports are published that demonstrate the resistance generation of GI nematodes to these chemicals worldwide [23]. Few studies reported the higher level of resistance produced against the broad-spectrum anthelmintics and also reported the side effects at higher dose levels [41]. A higher level of resistance in *H. contortus* is developed in the endemic areas of haemonchosis. Nevertheless, the side effects and resistance produced by the excessive use urged scientists to adapt alternative GI nematode control methods to reduce the risk of environmental pollution.

The consumer requested "clean and green" by-products that are free from residuals and growth promoters and cost-effective, and scientists were appealed to work for the launching of new and effective drugs and strategies [23]. Various factors such as frequent dosing of the same brand to infected and noninfected without discrimination, wrong choice, inappropriate administration massively involved in the development of resistance and reoccurrence of disease with re-exposure of the parasites [41]. *H. contortus* (roundworm) has been reported as resistant to all broad-spectrum families of anthelmintics [33, 35, 42].

Resistance is a global issue, and some regions are more exposed to it as compared with others, e.g., tropical and subtropical regions are more affected by the resistance of GI nematodes [33]. Soli *et al*., [40] reported multiple anthelmintic resistance in goats from Punjab Pakistan, and various other researchers also reported anthelmintic resistance in goats [33, 35, 42]. The most extensively used model for the control of nematode parasites is the use of chemical agents, and among these the most commonly used chemicals are benzimidazoles and avermectin. However, resistance development against these anthelmintics results in difficulty in the use of these chemicals as a control measure at the farm level [23]. High-degree resistance is reported in parasites against multiple chemical agents [43]. Along with *H. contortus*, some other nematode parasites develop resistance and are studied well, e.g., *Trichostrongylus* spp. and *Ostertagia* spp. [23]. Due to resistance development, the introduction of new administered drugs shows reduced efficacy [41].

Regions where haemonchosis is endemic and anthelmintic treatment is frequently used at the farm level are exhibiting more resistance in *H. contortus*. So, the use of alternative strategies is the necessity of time to control parasite burden at farm level, and also consumer demand is changed; they need cost-effective and residual-free strategies for control [23]. Some other methods are also used for the control of parasites in the animal industry, which are still underutilized and can be a more successful alternative against resistance development issues.

#### *7.1.2 Copper oxide wire particles*

In grazing ruminants, copper is administered along with diet as a feed additive to overcome the deficiency symptoms. The use of copper started in the 1900s, in various forms to minimize the worm load (SCSRPC). The use of copper oxide wire particles (COWPs) was found more successful in reducing nematodes, more precisely *H. contortus* [40, 43]. Following administration of COWP, it enters the abomasum along with the ingesta and sticks to the mucosal folds [44]. In the acidic conditions of the abomasum, stuck elements take several weeks to dissolve, and free copper is released slowly, which augments the soluble copper concentrations. Ultimately, copper reserve of the liver increases. The copper mode of action is yet to be understood, but researchers assumed that it alters the abomasum conditions that hinder nematode attachment and cause their death or expulsion. Following the COWP ingestion, an increase in packed cell volume (PCV) and a decline in EFC have been observed. The efficacy of COWP is higher against adult worms of abomasum but ineffective in the case of intestinal helminths [43]. Therefore, fecal culture is recommended to explore the higher population of *H. contortus,* before COWP administration [45]. The COWP is found to be equally effective against nematodes in both sheep and goats [40].

For administration in cattle, COWP boluses (Copasure©) of 12.5 and 25 g are available and for small ruminants, smaller dosages of 0.5–2 g are used [40, 43]. The *Anthelmintic Drug Resistance in Livestock: Current Understanding and Future Trends DOI: http://dx.doi.org/10.5772/intechopen.104186*

recommended COWP dosage for cattle of weight above 227 kilograms was 12.5 g [45]. The sensitivity of sheep is higher against copper, and a little higher dosage may lead to toxicity although COWP is released slowly. Risk factors of copper toxicity that should be considered during administration are animal breed, age, health status, and other minerals deficiency such as molybdenum, poultry litter exposure [46]. Investigation on the use of COWP among exotic artiodactyls has been performed at Disney's Animal Kingdom® Lodge. During the trials, four artiodactyl species included roan antelope, blesbuck, scimitar-horned oryx, and blackbuck. The corollary of their study indicated a marked reduction in EFC (above 90%) on day 7 post-COWP therapy. The animal species variations, liver health status, copper level, interaction level with other minerals, and history of copper supplementation should be considered before the implementation of the COWP GIN control program in exotic animals. Before the use of COWP in an integrated pest management program, the impact of COWP on reproduction, accumulation level, and sensitivity level among species should be investigated [45].

#### **7.2 Nonchemical methods to control GI parasitism**

#### *7.2.1 Biological control*

In this perspective, the naturally found pest antagonist organisms are used to control the pest population. Grønvold *et al*. [47] ascertain the role of fungi as nematophagous, earthworm, and dung beetle as anthelmintic [48], and these are potentially effective biological agents. Biological control is an effective way of overcoming the GI helminths. Mainly nematophagous fungus, *Duddingtonia flagrans*, is used to control the nematodes infesting GI tract. During the field trial, it shows encouraging results toward sheep and goats' GI nematode parasite control [42]. The fungal spores are fed to animals along with a diet that passes through the GI tract without harming the gut mucosa. Fungus sporulates in animal feces and their hyphae kill the nematode larvae in fecal material; hence, diminished the pasture burden of nematodes larval stage [49–52]. The use of nematophagous fungi is an effective alternative approach, but there is a limitation regarding delivery to animals and antagonist role of other drugs, namely benzimidazole as an antifungal agent. *Duddingtonia flagrans* also show their effectiveness toward the larvae that escape out after the COWP treatment, which proposes another application of biological control for helminths [43].

The biological control strategies were proposed to reduce the parasite population below the economic threshold and clinical level above that considerable production losses are there. High efficacy of *D. flagrans* was noticed against larval stages of various nematodes of cattle [47], sheep [53], and horses [52]. It has been proven by field trials that among grazing animals, daily fungal spores feeding for 3–4 months hinder the build-up of various larvae up to dangerous levels on pasture.

Sheep feeding supplemented with *D. flagrans* chlamydospores lowers the egg counts and improves animal weight gain in comparison with untreated animals [54]. For the application of nematode-trapping fungi against GINs of ruminants, a strategy was formulated [55]. *D. flagrans* can produce a large quantity of thick-walled chlamydospores, which makes them more effective against nematodes in comparison with other nematode-trapping fungi [56]. *D. flagrans* is used as a biological agent against nematode such as *H. contortus* in grazing animals [42].
