**7.3 Control through monitoring**

#### *7.3.1 Parasite monitoring strategies*

Strategies for worm load investigation: FEC, larval developmental assays (LDA), FEC reduction test, and fecal larval culture (FLC) have proved valuable linkage with monitoring and control of worm infection. Mainly FEC is used for monitoring and management of GIN parasites. LDA is used for nematode species identification and to explore the resistance level [57]. FLC helps in identifying worm species, seasonal variation, and enclosure of GIN population. FECRT is the most authentic approach to determine anthelmintic resistance, but it is expensive and labor-intensive [57]. The demands for the exploration of alternative strategies toward helminth control have been augmented due to the lack of new anthelmintics. The applications of plants having condensed tannins, COWP, nematophagous fungi, and other biological approaches in combination with anthelmintics, animal management, control of ecological factors, and GIN level monitoring strategies could be effective to overcome GIN resistance in small ruminants.

#### *7.3.2 FAMACHA chart and mac master technique*

Among TST methods FAMACHA chart and McMaster are mainly used way to identify the worm-infected animals and require treatment. The former method is used to diagnose anemic animals by comparing their eye (conjunctiva) color with the chart. The latter method provides a real-time picture of parasite burden via egg counting in fecal material. In the McMaster method, fecal material is suspended in floatation solution and supernatants are taken on a specific glass slide (Mc Master chamber) and observed under a microscope for egg counting. For reducing anthelmintic resistance among GI parasites, selective therapy is highly effective. By using the aforementioned methods, medicinal cost of animals declines because they selectively purchase few anthelmintics and animals are responsive against these drugs. On the other hand, selective therapy is laborious and time-taking, farmers have to perform the FAMACHA check once a month. Routine-wise performance of McMaster is mandatory because sometimes with FAMACHA check animals found healthy while through McMaster they were found with high worm burden, and such animals should be treated because these animals may act as a source for others. The FAMACHA score system is found to be highly effective in the selection of wormresilient animal breeds [58].

#### **7.4 Control through management**

#### *7.4.1 Pasture management, grazing management, rotational grazing*

For the control of GI nematodes infections, two most commonly used methods include the use of anthelmintics and pasture management; they are associated with reduction of production losses because of nematodes infections. Two ways of producing safe pastures and reducing the infectivity of pasture include rotational grazing and pasture spelling, this strategy is very [59]. In rotational grazing, it is assumed that significant larval mortality occurs because of break-in grazing. But, unfortunately, the period in between animal rotations makes the best use of available and nutritious forage coincides with the period during that high concentration of L3 becoming

#### *Anthelmintic Drug Resistance in Livestock: Current Understanding and Future Trends DOI: http://dx.doi.org/10.5772/intechopen.104186*

available for reinfection. In the United States, a study was conducted at a farm and reported that lambs raised under a rotational grazing system were highly infested with helminths in comparison with others. Most of them were infected with nematodes, *H. contortus*, and gained less weight in comparison with control (non-grazing). It is therefore concluded that rotational grazing is not a good option in sheep. In some situations, it is recommended to extend the periods between the rotations of (60–90 days) as it may significantly lessen the parasitic infection. Rotation of younger susceptible animals with highly resistant older animals may prove to be beneficial. But such a strategy may not be possible due to practical restraints [35].

#### *7.4.2 Manipulating supplementation of nutrients*

With the provision of a good and high level of nutrition, the productivity of animals can be improved with an increase in the immune response against parasites. With an increase in the level of proteins in the diet, an increase in the resistance and resilience of lamb against *H. contortus* has been observed [60]. The supplementation of a meal with sorghum and soybean for the grazing kids has shown increased resilience against helminth parasites [61]. Indeed, improvement in nutrition is an efficient strategy to lessen and compensate for the negative impacts of parasitic infection. Whereas approach to urea molasses increases both resistance and resilience in grazing East African goat kids in an environment overshadowed by *H. contortus* [62]. In a review by Hoste et al., [63], it has been discussed that the supplementary feeding to the goats has shown an increased response concerning resilience, whereas the effects on host resistance were less prominent.

#### **7.5 Control through medicinal plants**

In ethnoveterinary medicine, medicinal plants are used for the prevention and treatment of gastrointestinal parasitism. There is a wide range of medicinal plants or plant extracts that are used to treat almost every kind of livestock disease related to parasites. There are so many studies and available literature on the anthelmintic properties of plants and their extracts, which confirms the antinematodal effects of these plants [33, 42, 64–67]. In comparison to synthetic drugs the herbal preparations are way cheaper and easily available and thus have been used for a long time in the therapy of livestock diseases of helminth parasites [68].

Many plants and herbs are used as control agents for human and veterinary endoparasites, and the efficacy of each plant depends upon the chemical composition and secondary metabolites composition. The composition of a plant is a variable character depending upon soil properties, climatic conditions, geographical variability, and environmental conditions. Anthelmintic activity of a plant is variable in different areas of the world and depends upon the harvest of the plant, plant parts, which are used as anthelmintics, storage of the plant, and combination of different plant extracts [68]. Choice of extraction solvent is also an important factor that affects the solubility of secondary metabolites of the target plants usually water and methanol are used as extraction solvents. Ethanolic extracts are considered a better choice as they can easily enter the body of the parasite through absorption [69].

To determine the plant properties, two different study types are used. i.e., in vitro and in vivo, and each study type has some merits and demerits. In vitro studies are cost-effective and can study a variety of plants at the same time, allowing the study of specific parasites and their lifecycle stages [70]. While in vivo studies are lengthy

processes and can study a single plant at a time. Sometimes the result of the in vivo and in vitro can be different as the outcome of the study depends on the internal factor of the host and plant species, e.g., the digestive system of the host [71].

Till today 25% of modern pharmacopeia use plant-derived drugs and some semisynthetic using plant as prototype compound [72]. Anthelmintic efficacy of plants is derived from different parts, e.g., saponins (can cause teguments degradation and vacuolization), tannins, and polyphenols can form a protein complex in the rumen and increase the protein supply, interfere with energy generation, reduction in gastrointestinal metabolism, and ultimately death of the helminth and alkaloids (effect the transport of sucrose transfer from the stomach to the intestine and helminth glucose support is disturbed causing paralysis) [73].

#### *7.5.1 Condensed tannins*

Tannins are compounds that attach with proteins and other molecules and are used as a biological alternative against chemical anthelmintic; many plants naturally contain condensed tannins. There are two main groups in which tannins are divided: one is hydrolyzable tannins (HTs) and the other one is condensed tannins (CTs). Among the two of these groups, condensed tannins are more abundant and are naturally present in browse, legumes, plants, and forage. The concentration of CT, type of animal consuming CT, the plant itself, and the concentration of CT in the plant are the factors that stimulate the effects of CTs. The high concentration of CT can have negative effects, and the noticeable negative effect is reduced palatability that ultimately causes a reduction in intake and digestion, which exerts a negative impact on productivity [46]. There are several benefits of CT intake that include increased wool growth and growth rate, increased amount of bypass protein, reduced bloating, high milk production, as well as a high rate of ovulation.

The prominent and most important benefit of CTs is their positive impact on the GIN infection. It has been observed that CTs specifically *H. contortus* reduce the GIN infection, it also reduces the overall egg output through the reduction in female fecundity. In addition to this, there is also a decrease in the GIN egg hatchability and the development of larva in the feces. Concerning reduction in GIN infection, the most important and researched CTs include big trefoil, sericea lespedeza, sulla, and sanfoin [46]. When the animals are allowed to graze SL management benefits have been observed that are less exposure to GIN as the plant grows off the ground, and since there is also an increase in the level of proteins that causes a potential increase in the resilience and resistance.

#### *7.5.2 Plants as nutraceuticals*

The nutritional combination of animal feed affects the biodiversity of GIT fauna, which may affect the parasite fitness by altering the intestinal environment in which the parasites propagate [63]. Tannins, flavonol glycosides, sesquiterpene, and secondary metabolites are potential candidates for integrated nematode control at the farms level [63, 74, 75]. The plants having these properties are known as nutraceuticals, which are considered for both the nutritional value and as an anthelmintic. It has been reported that supplementation of bioactive plants to goats played role in the regulation of bionomics of resistant parasitic populations along with enhancing the ability of the goat to withstand negative effects of the pathophysiology of parasitic

infections [63]. An increase in post-ruminal protein availability playing role in reducing the parasitic infections in large ruminants has also been reported, which may be attributed to the availability of condensed tannins (CTs) or proanthocyanidins and polymers of flavonoid units [48].

### **7.6 Control through immunological interventions**

#### *7.6.1 Vaccines (immunization and vaccination)*

The most effective way of controlling infection is vaccination; therefore, demand for vaccine development against GI parasites rises. In disparity with vaccines of viral and bacterial pathogens, vaccine development against parasites did not gain similar success although parasitologists are working in this regard for the last 30 years. The vaccine has been developed against tapeworm and lungworm sheep and cattle respectively. Studies have been conducted in the identification of various antigens of nematodes as vaccine agents [76]. Gut-associated antigens have been reported as vaccine candidates, namely H-gal-GP and H11 of *H. contortus* [77]. Fecal egg count has been markedly declined in goat kids with the use of vaccine candidates. Secretory and excretory products of parasites have been found as effective vaccine candidates. It has been reported that the use of secretory and excretory antigens as vaccine candidates in infection of *H. contortus* results in enhancing the immunity of the host, thereby reducing the FEC and worm burden by 70% [78]. It has been reported that the use of H-11 and H-gal reduces 60–75% of worm burden and 80–90% FEC, and they can be good candidates for vaccine development [79]. Both of these candidates have been reported to induce protective immunity in terms of IgG production, PCV maintenance, FEC, and worm burden reduction in lambs and kids [77].

Traditional use of chemotherapeutic agents against infection of ectoparasites as well as endoparasites leads to the development of resistance against these therapeutic agents. It converges the scientists for exploring the nontraditional ways of controlling GI parasites; development of a resistant breed of the host through selective breeding, vaccine development, implementation of other control measures (alternate pasture grazing and rotational grazing), and synergistic use of anthelmintics [80].

In vaccines, acquired immunity plays a pivotal role in the protection of the host against pathogens, and it needs to be explored for the development of a vaccine. In the case of parasites, the role of acquired immune response is not fully explored. Therefore, vaccine development against GI parasites for protection remains ineffective [81].

Some fungi of *Arthrobottrys* spp. have been reported to attack and kill the larvae of nematodes in fecal pats, but these fungi are being killed by passage through the gut and therefore are of no great importance, but nowadays, a new fungus *D. flagrans* has been reported, which will grow and pass through the gut harmlessly and is active against larvae of nematodes in fecal pats [13].
