Not all manure is created equal... and do we know if there is "bad" bacteria in it?

28 January 2008 -- Farmers who have been snuffling up dust and dried you-know-what out of the sheep or cattleyards might be less likely to develop lung cancer, according to new research.

But according to some other research you might want to be careful what sort of manure you snuffle up. Possibly manure from animals treated with antibiotics might contain some less than savoury bacteria.
Click here for more on antibiotics and manure.

Scientists have found that dairy farmers were five times less likely than the general population to develop the disease. They thought this was related to the bacteria, which lives in the manure, which the farmers ingested.

But how much dried manure do New Zealand dairy farmers deal with? Probably not nearly as much as their overseas counterparts. Although there is probably plenty of dry cow manure on the cow tracks around the country it's more likely that it's the person lowest on the pecking order, or with the least experience, that is spending their time following the cows to the shed.

So, possibly in New Zealand it would be the dairy worker or sheep farmer who would be less likely to develop the disease.

Many researchers now believe that exposure to germs could be beneficial as it allows a person's system to build up resistance and there is a thinking that a sanitised, infection-free life might make a person more likely to develop certain diseases.

Interestingly US scientists now believe that several types of bacteria can be a farmer's friend when it comes to reducing the risk that antibiotic-containing manure may pose to the environment.

Livestock and poultry producers rely on antibiotics to treat a host of diseases and infections. In fact, more than 21 million pounds of antibiotics were administered to US farm animals and pets in 2004. Such treatments help promote animals' health and well-being, in addition to ensuring a safe food supply for consumers.

The trouble is, when animals excrete in their waste antibiotics and other pharmaceuticals that their bodies don't use, the compounds may linger in the environment. This so-called pharmaceutical pollution can encourage bacteria to mutate and form strains that are resistant to current antibiotics.

Californian soil scientist Scott Yates wanted to find out what happens to antibiotic-laced manure once it's mixed with soil, as typically happens when livestock manure is spread on to farm fields as a fertilizer.

Yates and colleague Qiquan Wang studied one commonly administered veterinary antibiotic, sulfadimethoxine, which is used to combat a number of diseases in livestock and pets.

They developed a mathematical model which revealed that thriving manure microbes play an important role in determining how quickly sulfadimethoxine degrades. Some microbes in manure can digest and inactivate the excreted antibiotic.

According to Yates and Wang, farmers should try to create a hospitable environment for these tiny helpers. They should store waste from treated animals in a warm, moist place for as long as possible before spreading it onto fields. This gives the beneficial soil microbes an opportunity to act on an antibiotic, before it has the chance to leach into soils and waterways.