IMPORTANCE OF LIVESTOCK SECTOR
There are multiple factors which play their role in establishing the economy of any country. Among these factors, Livestock have vital role in economic strength of any country by producing, milk, meat, wool, hide, farm yard manure and many other animal by-products. There are 1750.5 million heads of cattle and buffaloes, 2439.2 million heads of sheep and goats, 27.4 million heads of camel and 21554.8 million heads of chickens are found worldwide which are producing milk 770.8 million tons (cattle and buffaloes) and 4.5 million tons from sheep while camels are also producing about 1.7 million tons of milk worldwide while meat production of these species reported worldwide is about 65,838 thousand tons by cattle and buffaloes and 150,48 thousand tons by sheep and goat. In Pakistan, the livestock sector being the most important component of agricultural economy shares about more than 50 per cent in agricultural GDP. Large ruminants being the part of domestic livestock share big part in compensating the meat requirement by producing 47,951 thousand tons milk and 1,887 thousand tons meat while sheep and goats producing 860,00 tons of milk and 657,000 tons of meat while camel shares about 851,000 tons of milk and it also used as draught animal in desert area worldwide. Apart from production point of view, livestock sector also provide means of earning by giving source of employment and earning money by the sale of animals, their hides, wool and by products like butter, yoghurt etc.
FACTORS AFFECTING THE LIVESTOCK PRODUCTION
However, there are some factors which are effecting livestock population by decreasing their production and ultimate economic value of the animals. These factors include environmental conditions, socio-economic conditions, nutritional deficiency of animals, poor husbandry management, poor hygienic measures at farm, use of contaminated instruments and utensils etc. All these factors predispose the animals to different diseases caused by bacteria, viruses and parasites leading the animal towards emaciation, loss in general body condition, production loss and sometimes leads to death of the animal by exposing the animal to other life threatening conditions. Among these disease causing agents, prevalence of diseases caused by parasites is increasing day by day.
ROLE OF GASTROINTESTINAL PARASITISM
Parasitism is of extreme importance in livestock industry causing widespread economic losses worldwide, in terms of decrease in milk yield, meat production, growth rate, reproduction and loss due to mortality. The parasitism caused by parasites can be divided into 2 categories as endoparasitism caused by endoparasites likehelminthes and ectoparasitism caused by ectoparasites. Endoparasitism caused by helminthes is increasing day by day.
The prevalence of gastrointestinal parasitism caused by these helminthes is continuously increasing and the reason of increasing gastrointestinal parasitism is their antigenic variation. With the help of antigenic variation parasites can evade host immune response. In antigenic variation mechanism when a parasite e.g. Haemonchuscontortus enters into the body of host; it changes its surface proteins which are not recognized by the host immune system. In this way, antigenic variation not only aid parasite to evade host immune response but also allow the parasite to cause the re-infection of the susceptible host as antigen produced by the pathogen will not recognized by the host immune response and infection occurs again and again. Due to this ability of antigenic variation gastrointestinal parasitism cause economic losses at individual as well as at farm or herd level. Estimated economic losses in terms of production vary from 15-55% depending upon the hygienic measures taken and use of dewormers to control gastrointestinal parasitism. However, veterinary doctors and livestock producers are also trying to combat the endoparasitism by using chemical anthelmentics.
MEDICINAL PLANTS USED AGAINST GASTROINTESTINAL PARASITISM
The natural anthelmentics includes Neem, Tobbacco, Walnut, Tulsi, Garlic and Kalongi seeds of different plants and honey and vinegar mixed with hot water act as vermifugal substances as anthelmentics. Seeds of garlic, onion and mint has been used against gastrointestinal parasitism, extract of Tobbacco plant has been proved effective against various ectoparasites, some natural anthelmintic plants and their different parts like seeds, leaves, bark as such or their ether extracts which are proved to be effective against different helminthes include Azadirachta indica (Neem) against Strongyloid, Plasmodium and Trypanosomes, seed extract of Trachyspermum ammi Linn. (Ajowan) against Haemoncus contortus, leaves extract of Cannabis sativa Linn. Against Flukes and Trifolium repin Linn against Hymenolepis dimminuta. Allium sativumagainst Haemoncus contortus, Crataevanurvala and Artemesiapallens and Buteamonosperma against earthworm, tapeworm and roundworms proved effective.Ether and aqueous extract of leaves of the Adhatoda vasica proved effective against larvicidal and ovicidal activity of Nematodes. The stem bark extract of Acacia oxyphylla against Ascaridia galli (Nematode), seeds of Carum capticum against gastrointestinal nematodes of sheep, aqueous and ethanolic leaf extract of Adhatoda vasica has been observed for ovicidal as well as larvicidal activity against nematodes, leaves of Artimesiabervifolia (wormwood) and Zanthxylumzanthoxyloides (Fagara a native tree from Africa) in the form of powder has been proved effective upto 65% against eggs of Haemonchuscontortus in abomasum, hay of Cassava forage has been proved effective against eggs and larva of abomasal and intestinal nematodes of sheep and goats, Punicagranatum commonly known as (Anar) the roots and bark of the stem of this plant has been used as astringent (antidiarrheal) and anthelmentic plant and experimentally proved that the alcoholic extract of the stem bark of this plant inhibit the hatching of Haemonchuscontortuseggs to filariform larvae, the aqueous, alcoholic and ether extract from seeds of the plant Cucerbita maxima has proved its vermifugal activity experimentaly against Platyhelminthes (trematode and cestodes) and nemathelminthes (nematodes) both In Vitro as well as In Vivo trials. The alcoholic and ether extract of Mucunaprurita has been found active against the trematodes. There are numerious species of plants reported worldwide, which are effective against different species of helminthes.
FUTURE PROSPECTS AND PRESENT SCENARIO ABOUT MEDICINAL PLANTS
It is estimated that there are more than 35 species of plants which are being used worldwide against Cestodes, 20 against trematodes and more than 40 against nematodes. However, there are thousands of plant species which are being used by the small farmers and producers and have not been proved yet. Therefore, there is a need to identify and evaluate the species of plants as whole, as well as their parts (bark, leaves, stem, flowers and fruits). There is need to study that which part of the plant is effective either against specific specie of parasite or multiple species of parasites and how much concentration is sufficient to get response of therapy.
For this purpose,there are some tests which are available for diagnosis of resistance of parasites against anthelmentics and also to evaluate the efficacy of medicinal plants anthelmentic activity In vivo as well asin vitro. These test includes, eggs per gram (EPG),packed cell volume (PCV) showing degree of anaemia, worm recovery method, through proximate analysis of medicinal plants, egg hatch assay or larval development assay, adult development assay and DNA probes, Copro-ELISA (Enzyme linked immune sorbent assay) and PCR (polymerase chain reaction) are also available for research purposes but not commercially available. Although anthelmentic plants have good activity against various helminthes as well as other parasites but there is a need to study in detail about phytochemical properties of plants, their chemical profile at molecular level and their other properties and harmful effects of their excessive use so that in future we will be able to control increasing parasitism and ultimately minimize economic losses in terms of productivity.
The research is being conducted on the effect of medicinal plants on gastrointestinal parasitism of sheep and their mineral profile in molecular parasitology laboratory, University of Agriculture, Faisalabad. The result of this research will be helpful in identification of medicinal plants with their mineral composition and effect on gastrointestinal parasitism and provide guidelines for their safe use in livestock industry to control parasitism and ultimate economic losses.
The authors are associated with the Department of Parasitology, University of Agriculture, Faisalabad, Punjab, Pakistan. They can be reached at Abdullahmalik42@gmail.com