Cattle part of our heritage…botulism in Zimbabwean cattle herds

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WITH Zimbabwe poised to develop its cattle industry, my articles on cattle breeding and husbandry in Zimbabwe in the ongoing ‘Cattle Custodial Heritage’ series for the past several months have aimed to contribute to an efficient and sustainable livestock production system for Zimbabwe’s small-scale cattle producers in tandem with the Government’s Command Livestock Programme.

In their efforts to provide food and nutritional security for all Zimbabweans, the Government announced it was seeking to raise $432 million from the private sector to finance a specialised agriculture farmer support programme.  

Accordingly, the Minister of Lands, Agriculture, Water, Climate and Rural Resettlement, Cde Perence Shiri, informed the nation that the Command Agriculture Programme targets to increase livestock, fisheries and wildlife production.  

It is thus important that Zimbabweans improve their knowledge on livestock husbandry.

My articles are thus intended to assist the new indigenous farmer and hopefully kindle an interest in cattle ranching for scholars and interested citizens.

The important role of cattle as a store of wealth and as cultural, social and economic assets has been fully appreciated by indigenous Africans from time immemorial throughout Africa — Zimbabwe is no exception.  

The appreciation of the reproductive and investment value of cattle led to the reluctance to sell under the colonial settler-Rhodesian cattle marketing regime.

Following a recent three-week training programme on cattle husbandry, cattle disease control, global warming and climate change in SA, I was made acutely aware of how vulnerable cattle are to the current unpredictable meteorological, environmental and ecological phenomena occurring in Zimbabwe and other southern African regions. 

In these regions, tick-borne and other contagious diseases, endemic to cattle, are becoming more exacerbated especially during the rain season. 

A particularly debilitating disease, known as botulism, that affects mostly cattle, goats and sheep, is currently rife in several parts of Zimbabwe. 

Although botulism may occur throughout the year, it is particularly serious during the current rain season where I have received reports from Hwedza, Domboshava, Guruve and Masvingo following the dry winter months.

What is ‘botulism’ and what is its cause? 

Mechanism of action of botulinum toxin.

Firstly, I should stress that botulism is a toxin rather than an infection.  Because it is not an infectious disease, a sick animal cannot infect a healthy animal. 

It is found in decomposing organic plant or animal material containing clostridium botulinum bacteria that is swallowed by mouth when eating anything that is contaminated. 

It affects the animal’s voluntary motoric muscles as well as those involved in chewing and swallowing; resulting in partial or complete paralysis.  

Apart from cattle, sheep and goats, it can also occur in horses, donkeys, chickens, ostriches, waterfowl and sometimes pigs. Humans and certain fish species are also susceptible. Horses are the most susceptible to botulism, while pigs, dogs and cats are highly resistant.

Botulism is a paralysing disease caused by a potent nerve toxin produced by the bacteria clostridium botulinum

Toxins are produced when the bacterium is in the vegetative state and is either ingested in the feed or is produced by the botulism bacteria as it grows in the gut or in deep wounds.  

What is clostridium botulinum? 

Clostridium botulinum is a ubiquitous soil-borne pathogen which grows well in decaying organic matter.  

While in the last few years there were few sporadic and unconfirmed reports of bovine botulism in Zimbabwe, recent cases are becoming more common as I have recently witnessed in Hwedza, Mashonaland East, as well as Domboshava and Guruve in Mashonaland Central and in the Masvingo Province.

Clostridium botulinum produces at least seven types (A, B, C1, D, E, F and G) of neurotoxin; though antigenically distinct from each other, these demonstrate similar modes of action in the affected animal. Type D is the most important in cattle, Type C1 in chickens, ducks, cattle (to a lesser degree than D) and horses, while types A, B and E affect humans.

In humans, most cases of botulism are caused by toxins type A, B, E, and sometimes (though rarely) by F.  

Symptoms of botulism include double or blurred vision, drooping eyelids, slurred speech, difficulty in breathing or swallowing, dry mouth or muscle weakness that spreads throughout the body.

The spores of clostridium botulinum are widely distributed in the environment in soils, sediments and in the gastrointestinal tracts of fish and animals. 

The bacterium exists in two states — as dormant spores which are resistant to environmental degradation and as a vegetative state when the bacterium is growing under anaerobic conditions. 

Clostridium botulinum bacteria form resistant spores that occur widely in the soil in most parts of the world. 

They proliferate in decomposing protein-rich animal and plant matter, such as the carcasses of rats, mice, tortoises, hares and birds as well as in lucerne and bean hay. 

In this decomposing protein-rich matter, the bacteria produce extremely virulent toxins. If an animal ingests these toxins, they will be absorbed into its digestive system, leading to paralysis within two to six days and ultimately death in animals.

In southern Africa, outbreaks of botulism usually occur mainly in winter when phosphorous deficient soils predispose animals to botulism

Botulism toxin may also occur in decaying plant material or silage of high alkalinity.

In grassveld and grass pasture, the phosphate level of old, moribund grass decreases in winter. 

If the animals’ diet is not supplemented with phosphate added to the salt-lick or stock water, cattle grazing this grass can exhibit poor growth, weakness in the legs, a stiff gait and pica

The latter is a craving to chew on bones (osteophagy). Old, fibrous grass also lacks protein, further increasing pica. Extended drought makes the situation worse.

A clear sign that your area is deficient in phosphorous is your cattle showing an appetite for unconventional food or objects such as bones, wood and even old shoes and discarded clothes. 

Dr Tony Monda holds a PhD in Art Theory and Philosophy and a DBA (Doctorate in Business Administration) and Post-Colonial Heritage Studies. E-mail: tonym.MONDA@gmail.com

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