Mastitis a costly disease in dairy farming

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A MAJOR concern in the dairy industry in Zimbabwe is the prevalence of mastitis, a major health hazard for the dairy industry, especially among dairy cows on smallholder farms.
Mastitis, or bovine mastitis, is the inflammation of the mammary gland primarily caused by pathogenic micro-organisms.
It is one of the most commonly encountered economic problems by farmers in the dairy industry and can seriously affect the whole value chain.
A potentially fatal mammary gland infection, mastitis is a most difficult disease to control in a dairy herd; it takes careful management to keep it at bay since there are no vaccines currently available for mastitis.
Persistent mastitis in dairy cattle is an inflammatory reaction of the udder tissue; usually in response to bacteria invading the teat canal. 
It is most frequently caused by a bacterial infection, largely due to bad sanitation which consequently affects the quality and quantity of milk and can be very costly for dairy producers if left untreated. 
It is estimated that mastitis in the US costs the dairy industry about US$200 a cow, a year, or US$1,7 to two billion annually.
In the dairy industry, a clinical case of bovine mastitis can cost greater in high-yielding cows due to milk yield losses, increased mortality, and treatment costs.
Its negative effects can impact cow reproduction, milk yield and shelf life of dairy products derived from the cow’s milk.
Mastitis may be classified according two different criteria — either according to the clinical symptoms or the mode of transmission.
A cross-sectional study was conducted in recent years to determine the prevalence of sub-clinical and clinical mastitis and the associated factors in cows from selected smallholder dairy farms in Zimbabwe.
Physical examinations were conducted on all lactating cows for signs of clinical mastitis and multiple milk samples were collected from lactating cows for bacterial culture and somatic cell counting.
Cows were categorised as clinical if they exhibited clinical features of mastitis, or sub-clinical if no apparent signs were present but they had a positive bacterial isolation and a somatic cell count of at least 300 x 103 cells/ml.
Farm-level factors were obtained through a structured questionnaire. The association of mastitis and animal and herd-level factors were analysed using logistic regression.
A total of 584 animals from 73 farms were tested.
It was established that overall, 21,1 percent had mastitis; 16,3 percent had sub-clinical mastitis and 4,8 percent of the cows had clinical mastitis, with a herd-level prevalence of 49,3 percent.
In individual cows, pure dairy herds and dairy crosses were more likely to have mastitis compared to Mashona cows.
Farms that used pre-milking teat dipping were associated with reduced mastitis prevalence.
Mastitis is often transmitted through contaminated hands or materials and by the repetitive contact with the milking machine, or it can be transmitted via the oral-to-udder transmission among calves.
Since grouped calves like to simulate suckling, they will transmit the bacteria to the udder tissue of their fellow calves.
Feeding calves on milk may introduce some mastitis-causing bacteria strain in the oral cavity of the calf where it will stay dormant until it is transmitted elsewhere.
The bacteria will lie dormant in the udder tissue as the calf grows until it begins to lactate; then the bacteria activates and causes mastitis.
To curb this route of transmission calls for strict calf management practices. 
Ensuring that cows have clean, dry bedding also decreases the risk of infection and transmission.
Cows affected by mastitis can be diagnosed on the basis of abnormality of milk and/or hardening, swelling, heat, redness or pain of the udder (if it is clinical mastitis), or changes in quality and quantity of milk includes a watery appearance, flakes, clots or change in colour when a cow is infected.
When infected with sub-clinical mastitis, however, a cow does not show any visible signs of infection or abnormalities.
The culling of chronically infected cows can help keep at bay the prevalence of this pervasive and costly disease that afflicts the mammary glands of cows worldwide.
Research has shown that the high prevalence of mastitis in Zimbabwe is mainly due to unhygienic practices and conditions under which cows are kept and milked.
Ethno-veterinary medicines, which refer to people’s belief, knowledge, skill and practice relating to care of their farm and livestock was practised by my great-grandfather Chikambi-Zvimba.
I well-remember my grandfather speaking of how his own grandfather, my great-grandfather, kept a strict regime of cleanliness and would regularly carry out a thorough cleaning of the cattle pens and his cows and would wash their udders before and after milking.
As a precaution, he would sprinkle copious amounts of ashes and dried or burnt ashes of gavakava (aloe) on the hay in the cattle pens to prevent the various cattle infections.
The best advice one can recommend to small-scale dairy farmers is that cleanliness is next to Godliness!
Dr Tony Monda holds a PhD. in Art Theory and Philosophy and a DBA (Doctorate in Business Administration) and post-colonial heritage studies. He is a writer, lecturer, musician, art critic, practicing artist and corporate image consultant. He is also a specialist art consultant, post-colonial scholar, Zimbabwean socio-economic analyst and researcher. E-mail: tonym.MONDA@gmail.com

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