By the end of this chapter, you will be able to:
- confidently identify animals in the dairy herd that show signs of ill health or parasite infestation using the Livestock Production Manual.
- accurately observe and assess the health status of dairy animals to protect the whole herd.
- promptly report any cases of parasites or diseases to farm authorities following workplace policies.
- correctly apply the guidelines of the Animal Disease Act (Cap 364) when notifying about disease incidences.
- understand the importance of timely communication to prevent the spread of illness in the herd.
Mastering these skills helps keep the dairy herd healthy and productive, ensuring a successful farming operation.
Parasites constitute a significant health challenge in dairy herd management across Kenya, affecting productivity and animal welfare. Effective evaluation and control of parasites are crucial to maintaining a healthy dairy herd, reducing economic losses, and ensuring quality milk production. This chapter examines the types of parasites that commonly affect dairy cattle, focusing on internal and external parasites, their biology, impact on animal health, and management strategies relevant to Kenyan dairy farms.
Parasites that affect dairy cattle are broadly categorized into internal and external types. Internal parasites live inside the animal’s body, often in the digestive tract or organs, while external parasites infest the skin or external surfaces. Understanding these parasite types is essential for timely diagnosis and effective intervention to minimize their adverse effects on herd health and productivity.
Internal parasites, also known as endoparasites, inhabit various internal organs of dairy cattle, primarily the gastrointestinal tract. They interfere with nutrient absorption, cause tissue damage, and lead to clinical diseases that reduce milk yield and growth rates. In Kenya, where dairy farms vary from smallholder to commercial scale, internal parasitism remains a persistent problem due to climatic conditions favouring parasite development and sometimes inadequate parasite control measures.
Internal parasites include nematodes (roundworms), trematodes (flukes), cestodes (tapeworms), and protozoa. Nematodes such as Haemonchus contortus cause anaemia by feeding on blood, leading to weakness and reduced milk production. Liver flukes (Fasciola gigantica) damage liver tissue, impairing metabolic functions critical for milk synthesis. Tapeworms, though less common, can cause intestinal obstruction and poor nutrient absorption. Protozoan parasites like Eimeria species induce coccidiosis, resulting in diarrhoea and dehydration, especially in young calves.
Understanding parasite life cycles is vital for effective control. Most internal parasites have complex life cycles involving eggs or larvae shed in faeces that develop in the environment before infecting new hosts. For instance, Haemonchus larvae develop on pasture and infect cattle during grazing. Liver fluke larvae require intermediate hosts such as freshwater snails found in swampy areas common in Kenya’s highland dairy zones. These environmental requirements influence parasite prevalence and seasonality.
Internal parasitism manifests through various clinical signs including weight loss, poor body condition, diarrhoea, anaemia, reduced appetite, and decreased milk yield. In severe infestations, death may occur, especially among calves and immunocompromised animals. For example, a dairy cooperative in Meru reported significant milk production drops linked to undiagnosed liver fluke infections. Chronic parasitism also predisposes cattle to secondary infections and affects reproductive performance.
Accurate diagnosis is essential for targeted treatment. Faecal egg count (FEC) is a standard diagnostic tool used in Kenyan veterinary practice to quantify parasite burden by counting eggs per gram of faeces. Other methods include blood tests to detect anaemia or liver enzyme abnormalities indicating fluke damage. Post-mortem examinations and observation of clinical signs also aid diagnosis, especially in resource-limited farm settings.
Effective control of internal parasites involves integrated approaches combining strategic deworming, pasture management, and environmental modifications. Rotational grazing reduces pasture contamination by interrupting parasite life cycles. Use of anthelmintics should be based on FEC results to prevent resistance development. Incorporating biosecurity measures such as quarantining new animals helps prevent parasite introduction. Nutritional supplementation enhances immunity against parasitic infections, benefiting farms like those around Eldoret where high-altitude conditions favour parasite survival.
External parasites, or ectoparasites, infest the skin and hair coat of dairy cattle, causing irritation, skin damage, and transmitting diseases. These parasites compromise animal welfare and milk production by causing discomfort and stress. In Kenya’s dairy sector, external parasitism is a common challenge, especially in regions with warm and humid climates conducive to parasite proliferation.
The main external parasites include ticks, lice, mites, and flies. Ticks such as Rhipicephalus appendiculatus transmit East Coast Fever, a fatal disease in cattle. Lice cause intense itching and hair loss, reducing feed intake and productivity. Mites lead to mange, characterized by skin lesions and secondary infections. Biting flies like stable flies cause pain and blood loss, leading to reduced grazing time and milk yield.
External parasites generally have life cycles completed on or near the host. Ticks lay eggs in the environment, and larvae hatch to find hosts. Warm, moist conditions prevalent in Kenya’s dairy regions promote tick and fly populations. Housing hygiene and pasture conditions influence infestation levels. For instance, poor sanitation in dairy sheds near Kisumu increases fly breeding sites, exacerbating parasite burdens.
Infestations cause irritation, restlessness, and skin damage that can lead to secondary bacterial infections. Ticks cause blood loss and transmit haemoparasitic diseases, severely impacting herd health. Lice infestations result in hair loss and poor thermoregulation, affecting calves’ growth. Chronic infestations lower milk production and increase susceptibility to other diseases, as observed in several dairy farms in Nakuru County.
Diagnosis of external parasites is primarily through visual inspection of the animal’s coat and skin. Identification involves recognizing characteristic signs such as tick attachment sites, lice eggs (nits), and skin lesions caused by mites. Regular monitoring allows early detection and timely intervention, essential for maintaining herd health on commercial dairy farms in Nairobi’s peri-urban areas.
Control strategies combine chemical, biological, and management approaches. Regular use of acaricides and insecticides reduces parasite loads; however, rotation of chemical classes is necessary to avoid resistance. Maintaining clean housing and minimizing overcrowding reduce parasite habitats. Biological control using natural predators is an emerging approach. Integrated pest management tailored to local conditions, such as in county government dairy development projects in Laikipia, has proven effective.
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Create a free accountEffective dairy herd health management involves several critical practices starting with foot baths to prevent hoof diseases, and the use of isolation pens or paddocks to separate sick animals and reduce disease spread. Proper fencing ensures controlled movement and security of the herd, while disinfection and fumigation help maintain a hygienic environment by eliminating pathogens. Controlling parasites and pests is essential, including the proper disposal of dead animals to prevent contamination. Understanding the types of parasites, both internal and external, and employing chemical, biological, or integrated control methods are vital for maintaining herd health. Vaccination programmes protect animals from infectious diseases, while disbudding and dehorning procedures using hot irons, chemicals, wires, saws, or cauterization promote safety and ease of handling. Routine hoof trimming supports mobility and prevents lameness, and quarantine procedures are necessary to isolate new or sick animals. Finally, proper animal handling techniques ensure welfare and reduce stress, contributing to the overall success of dairy herd health management.
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