आंतरिक परजीवी: भेड़ और बकरियों में रोकथाम और नियंत्रण के उपाय

As we all know that, Indiais a paradise of many parasites due to its hot and humid climatic condition. Though most of our indigenous breeds are well adapted to the harsh environment, low nutrition and tropical disease, but animal welfare and productivity are highly affected by internal parasite infestation, mainly during rainy season.

Internal parasitism is one of the major problems in the small ruminant’s sector because it exhibits major health issues, which have deleterious effects on the animal performance and cause great economic loss to the producer. In fact, most of the economic losses produced by internal parasites are actually not due to mortality but production loss.

The most common internal parasites in sheep and goats are Lung worms (Dictyocaulusspp. or Muelleriuscapillaris), Stomach worms (Haemonchuscontortus) commonly called Barber pole worm, Liver flukes (Fasciola hepatica), and Intestinal parasites, the most common of which are coccidia (Eimeria or Isospora).

These parasites have become more difficult to manage because of developed resistance to nearly all available dewormers. Hence, the proper management of internal parasites is extremely important to the success of the small ruminant sector.

The ability to observe the clinical signs of a vital infection, to properly medicate and handle the herd, and to effectively reduce the herds exposure to internal parasites are the main aspects of internal parasite management.

Clinical signs observed during internal parasitic load

• Sick animals generally isolate themselves from the herd and their feed intake decreases.
• Due to decreased feed intake, animals don’t get all the nutrients they need and resulting weight loss.
• When nutrients are insufficient, the animals’ hair loses its luster - Rough hair coat.
• Animals typically shows sign of dull and depression, they keep their head and ears down and are not willing to stand for long periods of time.
• Animal suffered from Diarrhoea which can be inspected by dirty tail and hind end.
• Animals become week and easier to catch or unstable when walking.
• Anaemia detected in animals and their gums, perineum, and eyes appears white/pale due to blood loss.
• Fever or, in the late stages of disease, cold extremities observed in the sick animals (e.g., ears and legs).
• In case of lung worm’s infection, Fast breathing is observed because animals try to get oxygen into their damaged lungs.
• In case of stomach worms and liver flukes’ condition, Bottle jaw condition observed. Animals have fluctuant swelling under the jaw from the accumulation of fluid (submandibular oedema) and sometimes it can spread to under the abdomen.

Prevention and control measures of Internal parasites

The internal parasites comprise flukes, tape worms, round worms and protozoa, only a few of them account for the majority of complications for grazing animals.Thus, several control measures applied, on the host and off the host with or without chemicals will be useful for sustainable production of farm animals as per agro-climatic conditions.

Housing Management

Farm shed should be well ventilated and lighted to maintain required humidity and air circulation and avoid high humidity and low light conditions which will accelerate growth of parasitic population. Optimum number of animals should be placed in the farm shed. Overstocking or Overcrowding of animals in farm shed enhances the parasite population.

Feeders are used to fed farm animals because they cannot be easily contaminated with faeces and should be utilized for grain, hay, and minerals feeding.

Clean and fresh water should be provided to farm animals which can be free from faecal material. Watering areas should be situated in well drained places with gravel or even cemented floors. Facilities of proper drainage in the animal shed prevent the animals from the access to parasite infected water bodies and also reduce the chances of survival of the parasites. 

The newly introduced animals should be quarantined or isolated from farm animals upto 4–6 weeks and if required administer the anti-parasitic drugs in them. Proper dispose of manure or faecal material is recommended to avoid chances of parasitic infection by eggs, larvae, cyst, or other stages of parasites.

The bedding material should be allowed to degrade along with manure for better control of parasites as it acts as a crucial source of various parasitic infections and application of nitrogen fertilizers like urea (1:25) to the surface of manure also eliminate the parasites.

Nutrition Management

• Vitamin A, D and B complexes, Minerals like zinc, iron, cobalt, sodium, potassium, phosphorus, etc are essential for proper functioning of immunological phenomenon and developing the immunity against internal parasites.
• Adequate energy, protein, minerals, and water should be provided to farm animals.
• Other strategies like use of tree and shrub leaves to decrease intake of ground-based and contaminated feeds; feeding of plants with possible direct or indirect anthelmintic effect and cut-and-carry methods, especially during heavy rain or heavy pasture contamination situation, are very useful to reduce internal parasite in sheep and goats.

Pasture Management

• Animals should be allowed to graze clean or new pasture which have not been grazed since 6–12 months to fetch maximum productivity from them. Pasture fields should be rotated with field crops and have been recently renovated by tillage (Manipulation of soil).
• Hay and Silage crops containing field are not used as pasture fields of animal.
• Regular burning of old or grazed pasture should always be practiced to obtain parasites free pasture land.
• Overstocking of animals in a small piece of grazing land enhances the accumulation of parasites.
• Allowing animals to graze pastures too short should be prohibited because it leads to more parasites consumed, reduction in feed intake and also inhibits pasture regrowth. So, do not graze animal below four inches fodder length.
• Providing tannin-rich forages and diverse pastures can help animals to reduce the overload of internal parasites.

Controlled breeding or Genetics of animals

Several breeds of sheep and goats that show resistance to parasites due to their genetic makeup that causes them to host a smaller parasite load. Rearing of resistant breeds of sheep and goats are the best long-term weapon against internal parasites in animals.

Biological control

Biological control is a type of way to control over the targeted organism like parasite, by reducing the population of pathogen below a threshold level where it cannotcause clinical problems and/or economic losses in the animals. The nematophagous fungi and earthworms are efficiently used to reduce the parasitic load on crop fields.

Anti-parasitic drugs management strategies

Anthelmintics (anti-helminthes) are chemical dewormers used to treat infections of parasitic worms (helminths) in sheep and goats. There are a few types of anthelmintics that are commonly used for small ruminants are Ivomec©, Valbazen©, and Tramisol©.

Coccidiosis is normally treated with sulfa drugs (Albon©) and amprolium (Corid©) but they do not directly cure the coccidiosis, they mainly prevent secondary bacteria diarrhoea.

Anti-parasitic drugs are still an essential part of parasite control in the grazing sheep and goats.

The copper particles will increase concentrations of copper in the blood, so it is important to use low doses (0.5- to 1-gram doses for lambs or kids less than one year of age; 1- to 2-gram doses for ewes or does older than one year of age) to reduce the internal parasites in sheep and goats.

As per Indian climatic conditions the grazing animals must be dosed at least twice in year at the onset (May end) and offset of monsoon (September end).

Improving (maintaining) the efficacy of treatment

• Weigh animals to determine proper dose.
• Do not underdose.
• Use proper drench technique.
• Fast animals prior to treatment.
• Give multiple anthelmintic drugs [Rx].

How to Slow down drug resistance

• Do not deworm on a regular schedule.
• Do not deworm all animals in a group.
• Do not return treated animals to a clean pasture.
• Give all anthelmintic drugs orally at the proper dose.
• Do not underdose.
• Deworm new animals with anthelmintic drug from two different chemical classes.

Internal parasites cause economic losses through decreased production, cost of prophylaxis and treatment and death of infected animals.

Attention to nutrition and to pasture management will also help control levels of infection by reducing dependency on dewormers and lead to a more sustainable parasite-management program. Thus, adequate management of internal parasites is extremely crucial for successful livestock farming especially in the grazing conditions.

Authors

Dr. Anjali¹, Dr. Gururaj VK¹, Dr. Madhuri Patel², Dr. Rohit Kurhe³

¹ Division of Physiology and Climatology, ²Division of Pharmacology, ³Division of Veterinary Gynaecology

ICAR-Indian Veterinary Research Institute, Izzatnagar-243122, India

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