THE RECENT MANAGEMENTAL PRACTICES FOR PREVENTION AND CONTROL OF PARASITIC DISEASES IN RUMINANTS
Dr.Santosh Giri, Livestock Consultant,Varanasi.
India possesses rapid growing animal husbandry sector and moving towards to attain self-sufficiency in the production of livestock products . The animal husbandry department is a major contributor to the Indian economy and overall contribution is 28-32% in agricultural GDP and 4 to 6% of the national GDP. It also contributes 8- 10% of the country‟s labour power . India possess largest livestock population in the world .Livestock population in India is threatened by disease outbreaks, droughts, floods and other climatic anomalies. There are several diseases affecting livestock that causes serious effect on the production of animals, human health, trade of livestock and animal products, as a result the overall economic development will be affected .Improved quality and quantity of livestock products is necessary, in order to compete in the international market, which intern needs disease free animal health status .In recent times, emerging and re-emerging diseases of livestock, poultry and humans have tremendously increased. Emergence of new serotypes in various pathogens creates additional risk and warning to the livestock and human population.
Ruminant animals appear sustainable as they do not compete with man for food, play a crucial role in the conversion of low quality plant material and crop residues to high quality human food as well as return valuable plant nutrients to the soil. Parasite control in ruminant livestock is a first-order input in any sustainable animal production system. The “Sustainable Control of Parasitic Gastroenteritis in Ruminants” is thus encompasses a multidisciplinary approach involving integration of chemotherapy, grazing management, biological control, worm vaccines, genetic resistance of hosts, mathematical model based decision support and other strategies, if any. Control measures based on this knowledge include strategic anthelmintic treatments and various forms of grazing management. While these measures can reduce the frequency of anthelmintic treatment required, their effect on selection for drench resistance is more problematical, unless they can be combined with other forms of control to reduce our current dependence on anthelmintics.
Preventive measures
From the ecological perspective, serious problems with internal parasites indicate that changes in feed, field management or soil management are required. By changing the production method or by using preventive measures, it is not necessary to rely on dewormers too often.
(A)Pasture management ———-
Pasture management that is designed to prevent internal parasites requires long-term planning. It is by varying such factors as the density and age groups of animals and the time and intensity of grazing that serious infections can be avoided.
i. Animal density ——-
Overpopulation increases the concentrations of parasites. It is generally estimated that parasite infections increase with the square of the animal load per surface unit. Therefore, for a given parcel of land, parasite infestations are four times greater where animal density is doubled. Density varies depending on whether grazing is intensive or extensive. Where there is extensive grazing, Antoine (1981) recommends less than 10 lambs/ ha (varying according to context).
ii. Grazing height
About 80% of parasites live in the first five centimetres of vegetation. Parasite infection and multiplication are prevented by letting animals graze only 10 cm from the ground in a field where there are parasites.
iii. Grazing time ——-
The drier the grass, the more parasites will stay at the base of the plants. It is estimated that in wet grass, larvae can be found over 30 cm away from the pats, whereas they venture only a few centimeters away when the grass is dry. The risk of infection is greatly lowered by waiting until the dew has lifted or until the grass has dried after rain before putting animals out to pasture. The larvae of most parasites move to the tops of plants when light levels are low, that is, when the sky is overcast or at sunrise and sunset. They avoid strong light however. Limiting grazing time to when the sun is strong also diminishes the risk of infection.
iv. Grazing by age group
Since the susceptibility of animals varies with age, it is logical to graze the younger animals in fields where parasite populations are very low.
Organic farmers in developed country have established some rules to prevent internal parasites in lambs and ewes. Thus, in intensive grazing, lambs do not have access to paddocks or sections of a pasture already grazed by ewes or other lambs in order to prevent reinfection. Lambs should graze preferably in new pastures, hay or silage fields, or should be greenfed. In dairy herds, young cows can be slowly immunized by allowing them to graze in new pastures with two dry cows that serve as sources of infection. The ingestion rate of L3 larvae is therefore quite low, allowing for controlled infection and development of immunity.
v. Multispecies grazing
Producers who have more than one animal species (e.g. cattle and sheep) can alternate grazing of different animal species which, although not foolproof, can help to break the parasite cycles. Several parasite species cannot infect two different animal species. There are even certain species of worms that affect only a particular ruminant species. Cattle and sheep herds can be combined in three ways:
(i) Graze the cattle to “clean” the pasture after the lambs have grazed. The cattle ingest a significant quantity of mature larvae from the lamb stools. If the cattle are allowed to graze the grass down to 3 to 5 cm from the ground, many parasites will be killed off from exposure to the sun;
(ii) Graze the cattle before the sheep to control pasture quality;
(iii) Graze the cattle and sheep together where vegetation is abundant.
(B)Soil management —–
Deworming treatments have little effect if the animals are returned to the same larvae infested field. It is therefore important to clean the pasture as much as possible to reduce, if not eliminate, the parasites. Possible strategies for this are resting the land, planting, using amendments or fertilizers to reduce parasite populations, and improving drainage.
i. Resting the land
This consists in preventing the animals from grazing in the same field or paddock. Since freezing temperatures or droughts eliminate some infectious larvae, cold or dry periods can be relied upon to reduce or extend rest periods. A three-year rest period (short rotation) is required for a complete cleaning.
ii. Amendments and fertilizers
Amendments that change the pH, the mineral balance or that create an environment which is inappropriate for parasites may help to clean the land. The choice of amendment or fertilizer depends on the type of parasite. According to Nunnery (1953):
• Salt (sodium chloride) is appropriate for use against ancylostoma larvae such as Bunostomum. Salt must be used with caution on account of its deflocculating properties in clay soils, and should not be used on a regular basis.
• Liming and acidification with copper sulphate are appropriate against liver fluke (Fasciola), which is transmitted by snails.
• Copper sulphate is also effective against the Dictyocaulus lungworm. Mackenzie25 recommends applying 23 kg/ha of copper sulphate mixed with 90 kg/ha of sand in this case.
iii. Manure management
Manure to be used for spreading may be filled with parasite eggs and larvae. Composting is a good way to clean manure as the larvae and eggs of nematodes are destroyed at temperatures as low as 32 to 34C. They are killed in as little as one hour at 50C, and in less than four hours at 44C. It is important, when turning the compost over, to ensure that the outer layer which has heated less, be mixed towards the middle of the pile. Composting is a useful technique before manure spreading in the case of truly dangerous parasites like lungworm.
iv. Improving drainage
Pastures or parts of pastures that remain wet for long periods are an ideal environment for the survival of internal parasite larvae. Standard drainage of a field may reduce the larvae’s chances of survival and extend grazing periods Control of parasitic disease by- Using Vaccines Control methods in which vaccines would have a central role provide attractive alternatives. Parasite.
Biological Control-———-
Biological control is an ecological method designed by man for lower in a pest or parasite population to keep these populations at a non harmful level . In practice, applied biological control has no direct application to internal animal parasites especially in their parasitic stages which may be indirectly regulated by intermediate, paratenic or transport vectors even free living larval stages. Many organisms such as viruses (Leishmainia RNA virus-1 (LRV-1), Trichomonas virus), bacteria(Bacillus thuringiensis), earthworms, fungi (Paecilomyces, Arthrobotrys oligospora, Duddingtonia flagran, Verticillium chlamydosporium), spiders, ants, insects, rodents, fish(Gambusia affinis) birds, and other living things are found to contribute significantly toward limiting parasite populations such as arthropods, protozoans and helminthes of domesticated animals. Parasites are now controlled almost exclusively by chemical acaricides and anthelmintics. The development of resistance to these chemicals and their harm to the environment necessitate alternative control strategies such as habitat modification, use of pheromones and hormones, improvement of host resistance and biological control.
Judicial Use of Anthelmintics —–
a. Dose and move- The animals are dewormed and allowed in pasture.
b. Repeated anthelmintic dosing- is done during spring and early summer when larval population is high .
c. Targeted Selective Treatments- This means treating only those individual sheep that need it and is based on the knowledge that in any given population of sheep, only a proportion actually require deworming. This is called “over-dispersion” as mentioned previously. The trick is to correctly identify which sheep require treatment. The producer has only a few options to be able to do this effectively and economically.
Long Term Medication
a. Slow release- It is intraruminal placing of capsule made up of nonreactive metals and other material containing anthelmintic agent which is released slowly for a long time.
b. Pulse release- The device is like above but it is made in such a way that anthelmintics get released rhythmically.
c. Self medication- Anthelmintics are incorporated in urea molasses block (UMB). The animals take the dose of anthelmintics when they lick the urea molasses block.
Breeding Policy
Work has been carried out on detection of naturally resistance animals against some particular parasites. Red Masai sheep is the most resistant breed against Haemonchous controtus. Indian Garole sheep have been found to be resistance against many parasitic infections these breed can be used for breeding .
Remote Sensing by Satellite Image
Analysis Disease mapping and risk assessment are important to medical and veterinary epidemiology. The development of newer accurate and easier methods for mapping diseases has progressed considerably in recent years. Geographical Information Systems (GIS) and Remote Sensing (RS) represent new tools for the study of epidemiology, and their application to parasitology is increasing particularly to study the spatial and temporal patterns of diseases. Their application in parasitology has proved these technologies to be useful and cost-effective tools for: data capture, mapping and analysis for the development of descriptive parasitological maps.
Use of Bioclimatographs
These explain the distribution in space and time of larval nematodes on pasture and represent the first rational attempt to utilize climatic observations to explain important features of epidemiology of helminthic diseases.
Conclusion
• Parasite control starts with good knowledge of the parasites and how they affect livestock.
• Susceptibility and resistance to internal parasites in animals is affected by several factors including the season, the age of the animals, nutrition, and pasture management.
• Fecal counts are worthwhile to detect the types and number of parasites affecting the herd or an individual. These should be done in critical periods such as spring and fall.
• As prevention, animals should not be allowed to graze when pastures are wet. Young animals should preferably be put in new pastures where parasite levels are low. Manure should be composted and soil drainage improved where needed.
• Deworming can be done when the animals are put out to pasture and again three weeks later.
Reference-On request
