Sustainable management of gastrointestinal parasites of ruminants

 INTERNAL PARASITES have always been a problem for livestock farmers all over the world. Whether the animals are grazed on pastures or stall-fed, they must have encountered internal parasites in their lives. Animals of humid areas have been found more prone to internal parasitic problems as compared to those of dry and arid rangelands. Chemical dewormers are losing their efficacy with the passage of time as complaints are emerging from various parts of the world. One of the probable reasons is the development of anthelmintic resistance in worms. This is causing the fear in the farmers community for the economic losses coming forth due to the parasitic burden on one hand and use of inefficacious drugs on the other.This problem lead the people think of other alternatives. However, in any control programme, some aspects of the farm management can be dealt to minimize the risks of internal parasites and economic losses attributable to them. In Pakistan, implementation of these recommendations is of serious concern. This will allow the small holder farmers of the country to decrease the economic losses by getting benefits up to the maximum genetic potential of their animals.

In context to all this discussion, following are given a few management suggestions for internal parasites: (a) Nutritional status: Good nutrition plays a key role in improving and strengthening the immune system of animals. Nutrition is the key aspect, which enable animals to overcome the detrimental effects of internal parasites. Poor nutrition can mislead the farmer for parasitism. Researches have shown that animal placed on higher plain of nutrition were able to lessen their worm burden significantly and even some sheep cured themselves. (b) Pasture Management, the major part of a parasitic life cycle is outside the animal i.e. on the soil/pastures. Usually farmers keenly monitor animals, but seldom pay attention to plants and soil.

The animals graze over the pasture, hence contaminating it with infective larvae, which are then taken up by the animals and become infected. Switching the pastures to rest will ultimately reduce the contamination and soil organisms to work well. This is so because of earthworms, dung beetles and nematophagous fungi will destroy or keep lot of parasite eggs and larvae from developing. Lush green grass to provide animal with adequate forage quality and quantity will keep the animal healthy and strengthens the immune system.

Stronger immune system will prevent the parasites from producing eggs, whereas on the other hand, the malnourished animals are more prone to heavier parasitic burden. Larvae crawl up the grasses and fodders up to an inch or so. Sheep eat much closer to the ground, hence eating a handsome amount of larvae. This is one of the reasons why sheep acquire more internal parasites. Sudden release of infective larvae and eggs within the ewes intestinal tract, right after the lambing is known as periparturient rise. This occurs so because at time of lambing the females immune system is depressed and the parasites get a chance to increase their number. Sheep and goat should be treated at this time to minimize the risk. (c) Cleanliness is the key to success. Feed and water troughs polluted with feces and drinking water from the community ponds increase the chance of infection. (d) Feeding fish-meal, Feeding fish meal as a source of by-pass protein will maintain the animal health, enabling the animal to combat against the parasites. (e) Immunological condition, It is not advised to completely remove internal parasites in animals. Most animals develop immunity against parasites. This immunity keeps the parasites from reproducing but rarely kills them.

In the light of all the above-mentioned parameters influencing the parasitic load in ruminants, following step-wise strategies are commendable for appropriate control measure in the ruminant livestock population of our country:

• Regular monitoring of animals for parasitism.

• Provision of ample quality and quantity of forages, clean water and confortable bedding, it enable animals to overcome its deficiencies and better equipped against infections.

• Feed by-pass protein sources to improve health and immunity.

• On pastures, graze younger earlier than adults.

• Dewormers should be used with great care to avoid toxicity in animals and resistance development in parasites.

• Lavish use of antiparasitic drugs (e.g. ivermectin) should be discouraged.

The writers are associated with Department of Parasitology, Faculty of Veterinary Science, University of Agriculture, Faisalabad.