Thursday, 17 February 2011 12:17

Cows can swim but floods have lasting impact

Written by 
Rob Bonanno Rob Bonanno

AS I write, I am shocked and saddened watching the floods that are devastating Queensland and northern NSW.

With the terrible loss of lives, and livelihoods, my heartfelt sympathy goes to all those who are impacted by these huge floods.

I had an unusual enquiry last week regarding how well cows can swim.

By a fortunate fluke of design, cattle have an innate ability to swim and float in a legs down head up position.

Cattle have been recorded travelling in floodwaters for many, many kilometres.

There are many ways that flooding can impact on dairy cattle. Because much of the land which dairy cattle graze in Australia is on various flood plains, it is quite common for flooding to affect dairy cattle

Floodwater can cause difficulty in physically milking the cows due to isolation of cattle or no power being available to milk the cows even if you can get them to the shed.

When cattle go unmilked for prolonged periods, it can have marked impacts on milk production as the cows will begin to dry themselves off.

Cell counts will increase followed by a surge in clinical mastitis either from new (environmental) infections or from previously sub clinical infections flaring up.

Cows in mud, with a heavy fly burden, left unmilked is a recipe for a summer mastitis disaster.

Summer mastitis is usually caused by A. Pyogenes and is characterised by thick custard like pus, a poor response to antibiotic treatment and the cow generally losing production in the quarter(s) which are affected.

Being caught in fast flowing floodwater will commonly physically injure cattle, breaking limbs and damaging udders and teats on fences and submerged obstacles.

Trapped or exhausted cattle will drown.

Once the floodwaters pass, the surviving cattle will face many threats and challenges.

Floodwater does not respect boundary fences so there is a risk that straying cattle can cause a breakdown of farm biosecurity. Manure and dead carcasses may contaminate feed and water supplies.

There is an increased risk of diseases like Leptospirosis, Blackleg and other Clostridial diseases, and Botulism is a high risk due to rotting animal and vegetable matter.

Vaccination will be a key prevention strategy to reduce the risk.

Spoilt and mouldy feed will potentially have huge burdens of moulds and fungus which may produce toxins that can rob production or, at worst, cause fatal toxicosis.

Stock that has been without feed for several days must be managed carefully when reintroducing them to feed, especially high starch rations.

Following flooding, there is also the risk of the growth of toxic plants and weeds, nitrate/nitrite poisoning and metabolic disease caused by rapid regrowth.

In the weeks and months that follow the flooding, it will be incredibly important to involve your veterinarian in all the key areas of disease prevention, biosecurity, welfare, nutrition and milk quality. This will ensure the best outcome for you and your herd.

I would like to reiterate my most sincere best wishes for all of you who are dealing with this cruel disaster after such a long drought.

Rob Bonanno is president of the Australian Cattle Veterinarians Association and a director of the Shepparton Veterinary Clinic.

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