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Newsletter of Penn Dutch Cow Care August 2012

Hi Folks,

Parasites love heat and humidity. Unless you’re in the drought stricken areas that are extremely dry, the very warm summer temperatures this year are helping parasites multiply in very short times. Parasites are those creatures which serve no real purpose but to live for themselves - at the expense of other living beings. Parasites can be internal or external. Important internal parasites of livestock usually bring to mind stomach worms and coccidia. There are many more, but those probably cause the most problems. External parasites bring to mind flies, lice and mange. Flies torment animals during the warm season while the effects of lice and mange tend to be seen during the indoor housing times of colder season.

Right now, unless your paddocks are scorched, parasites are thriving and sending millions of eggs out onto pasture as your herd animals drop their manure on the ground. The eggs hatch in a few hours, soon crawl up the blades of nearby grass hoping to be eaten by animals as they graze, then start their life again in the host, sucking blood from the stomach walls. This is basic biology and there’s no getting around it completely. Parasites (of any kind) will always be present wherever there is a high animal density in a contained area. Only the free roaming bison on the American Plains could constantly move along and not encounter heavy pressure of internal parasites. However, there are ways that you can reduce the pressure while also keeping your animals healthier by eating better. How? By using rotational pasture management so animals get new paddocks every 12 hours and by giving the paddocks a rest once grazed in order to re-grow. Just as important, dragging pastures to spread out manure will allow quicker drying out of manure to kill the fragile microscopic larva crawling about. The ideal time to drag out manure pies is 2-3 days from when the cows are on the paddock. This will not hinder pasture re-growth and more importantly will allow the dung beetles to do their work. This timing also allows time for horn flies and face flies to lay their eggs, so eggs will be hatched and the fragile young larva can also be killed by spreading out the manure pies and quickly drying out their living areas of internal parasites and developing flies.

Speaking of flies….it seems impossible to tell when a farm may experience a bad season. In the same season, farms in the same area may experience vastly different fly populations. Why is that? I certainly don’t have the answers, but when farmers apply concepts of biology, chronic problems like flies can be managed better. Take for instance that flies like warm, humid conditions and flies don’t like wind. How many times are you bothered by flies on a windy day? Applying this basic concept to farms would indicate that air flow in the barn would mean dramatically less fly problems in the barn. Lo and behold, go into a barn that has tunnel ventilation and you will experience few if any flies. It certainly need not be tunnel ventilation, but something about tunnel ventilation simply works extremely well against flies.

You have probably heard by now off the Spalding Fly-Vac: a machine which generates high velocity wind in a large walk through chamber. It also has a vacuum aspect which sucks the flies into a large jar that have been blown off the cows. Without a doubt this is the best way to reduce the amount of flies from tormenting your cows as well as eliminating them from the breeding population, thereby lowering fly numbers throughout the fly season. They are now commercially available (see your trade magazines). It was developed at North Carolina State University.

At the 180 cow dairy herd at NC State Center for Environmental Farming Systems (CEFS) in a time of one week, 410,000 flies were eliminated and during the second week another 457,000 were eliminated. Horn fly densities were reduced from 775 per cow to 263 in the first week and down to 150 per cow by the second week. This is a 70% reduction in flies compared to cows not going through the fly trap. In the 3 month study between late May and late September, over 2.4 million flies had been removed from the 180 cows.  That is an amazing amount of flies taken out of the system, no longer tormenting the cows nor rapidly reproducing. These same fly traps have also removed over 15,000 face flies and 8,000 stable flies. Face flies are the ones that carry the pinkeye bug. In bad situations, there may be as many as 100 flies per face. It is well known that reducing face flies to less than 10-15 per face will reduce the spread of pinkeye and maximize animal comfort. (from: Managing Parasite Flies in Pasture-based Dairy Systems by Dr. Wes Watson and Steve Demming, presented at the Mid-Atlantic Grazing Conference, July 2012).

Horn flies are smaller than other kinds of flies and are usually found on the bellies and backs of cows; horn flies deposit eggs in fresh manure and it takes 9-12 days to develop into an adult. They take 10-12 blood meals per day and can transmit Staph aureus between animals. Face flies also lay eggs in fresh manure and are adults in 14 days; face flies have been found to carry over 30 bacterial diseases and are the main carriers of the pinkeye bug. Stable flies are found on the lower body and legs of cattle and take about 2-3 blood meals a day; stable flies prefer aging manure and bedding or round bale feeder areas to deposit their eggs. Cattle bunch up trying to avoid painful bites. House flies will use a variety of organic materials to lay their eggs and it takes about 7 days for them to become adults. (Watson and Demming, 2012).

With these things in mind, maybe it is easier to see why I have always promoted clipping and/or dragging pastures to destroy the manure pies and allow even re-growth of pasture. Just wait 2-3 days so the dung beetles can drill manure into channels they create in the soil. This action of dung beetles is incredibly important. While I will always promote a multi-prong approach to solving problems, if there was ever a “one- stop shopping” method of dealing with flies, the wind/vacuum chamber is it. (I have no financial interests in the product.) While other methods like sticky tape catch random flies and parasitic wasps will help reduce flies from becoming adults, the fly-vac basically wipes out large numbers quickly - right off the cows - which will make your cows more comfortable, allowing them to graze better. The fly-vac may well be the single best invention yet for non-chemical fly control. Applying basic biological concepts such as the action of wind will reduce fly burdens and drying-by-dragging will reduce the habitat of parasites in pasture, making your cows happier and more productive.



 

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