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The Killing Fields

Managing Sheep To Prevent Bloat


By Laurie Ball-Gisch

The Lavender Fleece

3826 N. Eastman Rd.

Midland, MI 48642
www.lavenderfleece.com
lavenderfleece@charter.net


“What does a bloated sheep look like?” was the question on the phone late Sunday evening.

The question brought back some nightmarish images to my mind from the first time I saw bloat: Walking out in the early spring evening to discover a ewe just outside the barnyard gates, upside down with stomach “bloated” (distended, taut like a drum) and her four legs straight up in the air. Green froth was coming out of her nostrils and mouth and she was dead.

Fast forward 12 hours: Walk out to the barn to check for eggs and turn to see a ewe in the corner of the barn upside down, same position, same image. But not believing my eyes! How could I have another dead ewe?

This Suffolk's rumen bloated from alfalfa pastures, wet with dew.
This Suffolk’s rumen bloated from alfalfa pastures, wet with dew.

To answer the phone caller’s question I wanted to say “Bloat usually looks like dead.” (But bloat can also look like “cast”-when a sheep ends up on its back and cannot “right” itself-and sometimes it’s hard to tell whether the sheep bloated and then cast, or cast and then bloated. I guess it doesn’t really matter, since it usually means a dead animal either way).

What Is It?

In the simplest of explanations, bloat is an excess of gases in the rumen of sheep. And it should always be considered an emergency situation.

Bloat is usually caused by lush pastures heavy in legumes-clover, alfalfa-the gases in their rumen cannot escape fast enough. These rapidly fermenting foods produce gases more quickly than sheep can digest.

From a sheep book written in 1947 called Sheep Science: “Certain individuals bloat to some extent on almost any kind of feed. Bloating is characterized by great distention of the upper left side of the abdomen….”

Bloat In Bottle Lambs

Nursing lambs seldom bloat (although too much rich milk from the dam can cause acidosis), but bottle fed lambs can bloat.

The following “recipe” is posted on my website and I received an e-mail from a shepherdess in Scotland one evening who wrote that she had a bottle lamb exhibiting frothy bloat and in desperation she did an internet search for a solution. The search engine brought up my webpage about bloat. She said she mixed up the formula, administered it to the lamb, and the lamb was saved.

Mix 1/2 teaspoon of ground ginger with 2 tablespoons of water and then shoot it down the throat of the lamb with a syringe. (I regret that I do not remember the source for this treatment).

How To Identify Bloat

From Dr. David C. Henderson’s The Veterinary Book for Sheep Farmers we learn the clinical signs of bloat: “If bloated sheep are still on their feet when found, they may stand very stiffly with their legs wide apart. They may pant excessively and stagger about if moved. They urinate and attempt to dung frequently. A swelling will be seen in the animal’s left flank and also on the right side in advanced cases. The pressure of the swollen rumen presses on the diaphragm, causing difficulty in breathing and finally suffocation and heart failure.”

Very often a bloated sheep will also have droopy ears and a glassy look to its eyes.

Dr. Henderson goes on to say: “Prevention is difficult, since many of the methods advocated are impractical. Restricting grazing time or total avoidance of suspect or obviously dangerous pastures is the safest approach.”

Those dangerous pastures-those killing fields-are also those that can produce the best lambs and stock more sheep. Dangerous pastures are those most rich in alfalfa or clovers, those pastures that best nourish lactating ewes in the spring. Ewes with such a lush diet produce abundant and rich milk for their lambs.

Fortunately (or unfortunately) the pastures that surround our farm are very productive, very improved hay fields with as much as 50% alfalfa and clover. As we continue to fence the fields outward, every new section of fencing means more vigilance to keep the flock safe from bloating. Over a couple of seasons, the sheep eventually eat down the alfalfa so the problem in our older pastures is less acute.

“Several contributing causes of bloat include: an inherited tendency for bloat, certain proteins in forage, the amount and rate of roughage intake, the coarseness of the roughage, the rumen microbial population and enlargement of the lymph nodes between the lungs which compress the esophagus or interfere with the function of the vagus nerves.” (Herrick, p. 99).

Unfortunately many times one discovers a bloated sheep too late to save it. But, like all things that sheep teach us (if we pay attention and learn our lessons) we can learn to recognize danger zones for bloat and keep remedies on hand that can help to thwart a death should one discover a sheep early enough to save it.

Bloat management and prevention is something that can be achieved if the shepherd has the time to turn sheep out several times per day, for very short periods of time. It takes about 10 days to change over the bacteria in the rumen (especially crucial when going from winter hay feeding to putting sheep on fresh spring pasture).

Keeping that time frame in mind, one approach is to try to get sheep to fill up on hay in the early morning and turn them out onto the pasture for periods as little as 10 minutes, several times a day.

However, once sheep taste fresh spring grasses, they will be more reluctant to eat the dry hay. It is important to gradually increase the exposure to pasture to give rumens time to adjust to the new, lusher forage. This is time consuming, and moving sheep back in when they are eager to eat that fresh green grass is not easy to do. This is one of the reasons we now have Icelandic sheepdogs-to help us move the sheep off spring pastures several times a day.

It is also suggested to not allow sheep onto pastures until after the morning dew is burned off by the sun. What is problematic for us here in mid-Michigan is that our early spring and summer is usually very wet, with frequent rains, keeping the pasture moisture content high. Some argue that it is the wet lush pastures that cause bloat, while others say that moisture content is not the issue. Most recommendations will be that mixed pastures are safer. And if you do have alfalfa and clover, limit them to less than a 50% concentration. Sowing fields with an alternative legume, birdsfoot trefoil has been recommended, as it supposedly does not cause bloat problems that the other legumes are known for. We will be trying this strategy the next time we need to reseed our pastures.

It’s important to know that sheep can bloat on hay too-especially risky is a sudden change to a hay that is heavy with alfalfa and/or clover. In making any changes to sheeps’ diets, always make the changes slowly and gradually.

(Also note that rams-especially ram lambs-can be at risk when eating too much alfalfa; a diet too high in protein can cause “pizzle rot,” and too much calcium can produce kidney stones).

Stress Causes Bloat, Too

Even when sheep have been eating just hay, they can bloat due to some other stressor.

One spring morning I was giving a tour of the farm with some elderly ladies from a local garden club. When we walked through the greenhouse (which is next to the barn and pastures) I saw a ewe come out of the barn with green foam coming out of her mouth and her rumen drastically distended. I turned to the ladies and said “I’m sorry, I have an emergency situation here.”

I then ran to the house, got the bloat remedy, and miraculously was able to catch the ewe (another key to the equation of saving their lives). Then I straddled her, administering the bloat formula orally for about 20 minutes, allowing her time to swallow and absorb the liquid. All the time I was acutely aware of the women in the greenhouse gaping at me through the glass as they observed my life-saving ministrations. The ewe did survive, but I also kept an eye on her the rest of the day, put her into an area where she couldn’t eat anything else and when she would lie down, I would make her get up and walk around.

The only thing different about the bloated ewe’s environment that day was that it was early May; she was not on pasture and her hay had not changed. The temperatures had been in the 40s with rain. That day the temperature had suddenly soared to the 80′s and the sun came out. I believe it was the stress of the sudden heat wave that put her rumen into distress.

This past summer, which was especially hot and humid, with many, many days in the mid to upper 90′s, we had a ewe come up from pasture about midday, clearly bloating. I was out of town, but my husband and father-in-law saw her and did treat her with the bloat formula. Unfortunately the stress of the very dangerous heat and humidity of that day resulted in her eventual death a few hours later. The sheep had been on free range pasture for two months and so it was not a case of forage bloat due to legumes.

Fighting Bloat

Prevention is obviously desired, but even the most vigilant of shepherds lose sheep to bloat. Most frustrating for me with the bloat problems we have had is that I have been very aware of the dangers of pasturing sheep in early spring. I have always limited their exposure to lush spring grasses. They are allowed 15 minutes to graze and brought back in. I will do this several times a day, gradually increasing their grazing time. So it wasn’t like I just said one morning “Ok, pastures are ready, here you go girls,” opened a gate and let them have at it. I was vigilant, but obviously not enough for some of the sheep.

I now really believe that there is a genetic proponent to bloat. We have noted that bloat can run in family lines. The daughter and granddaughter of that first ewe that I lost to bloat ended up bloating in subsequent summers on another farm (which incidentally did not have any alfalfa in their fields).

One shepherd I know has described the sheep that tend to bloat as the “gobblers” or those most greedy sheep who run from plant to plant taking just the flower tops (or the sheep candy) instead of consuming the rest of the plant. Knowing this you can observe your ewes as they go to new pasture. Pay attention to their eating habits. Those that are running from plant to plant may be the ones you will have to keep a closer eye on. Those that pick a spot and just eat slowly and steadily usually have a bit more sense about what’s good for them.

One summer we opened up a new field in August (well after the sheep had been free grazing for several months already). Knowing there was a new concentration of alfalfa and clover in those ungrazed areas, I let the ewes and lambs onto that section for 30 minutes and brought them back up to the barnyard. I had to leave the farm for an hour and when I came back, I discovered one of the adult ewes upside down, dead of bloat.

As if that wasn’t bad enough, later that evening I discovered one of the ewe lambs circling, showing classic symptoms of “polio” (polioencephalomalacia).

“Evidence implicates a condition called acidosis. A shift in the acid state of the rumen may bring on this condition. The shift produces an enzyme that blocks thiamin reactions, which in turn result in a build-up of chemicals that destroy central nervous system tissues. Others say acids build up in the blood and irritate the nervous system.” (Lawson, pg 121).

This was the one and only case of polio we’ve ever encountered in six years and the coincidence of this lamb having been on the new lush pasture, coupled with the bloat death of the adult ewe, led me to conclude that the lamb suffered acidosis from the lush pasture, resulting in a sudden thiamin deficiency. Polio “…happens most often when lambs are rapidly placed on readily fermentable carbohydrates as is found in grain concentrates. Occasionally, it can happen when animals are changed to lush pasture after being on over-grazed pastures.” (Lawson, pg 121)

Although we treated her “by the book” for the polio symptoms, she died the next day.

Sheep can also bloat due to incorrect grain feeding. When adding grain to their diet, it’s important to add it very gradually. Laura Lawson (pg 46-45-47) distinguishes between “rumen bloat” (caused by grazing on lush legume) and “abomasal bloat” (most often found in lambs who haven’t yet developed their rumen to its full potential.) She also distinguishes between “free-gas bloat” and “frothy bloat” and goes into much detail about how to tell the type of bloats and how to treat them. I highly recommend every sheep breeder get a copy of both of her books. (These books are available from the sheep! bookstore on page 42.)

It’s very important to store any grain containers well away from the sheep so that they can never get into them. I’ve heard of sheep escaping their fencing only to find their way to the storage areas and gorge on grains around the farm and eating their way to a painful, bloated death.

Treating Bloat

Treatment of bloating sheep consists of measures that will stop the formation of additional gas and will assist in the removal of the gases already present.

I keep on hand bottles of “Bloat Gard” that I purchase commercially. This is one that I like the best because it’s ready to use and all I have to do is catch the suffering sheep and get them to swallow the bloat remedy-giving them the entire bottle.

There is also another product that requires pre-mixing before administering. And there are also many different home remedies for treating bloat. Be sure to consult your sheep books or your veterinarian. They will recommend other methods that may include forcing a hose down the gullet and in extreme emergency situations, a hole can be made in the rumen to let gases escape.

Mike Neary, Extension Sheep Specialist at Purdue University published an article that is on the internet at http://ag.ansc.purdue.edu/sheep/articles/pasbloat.html. He recommends the following:

“Treat bloated sheep with care. The build-up of pressure in the rumen can actually cause a partial collapse of the lungs. Furthermore, blood from the body is forced out of the body cavity to the extremities and can cause a form of acidosis. Thus, stressing these animals complicates the situation.

“If animals can be caught, use a stomach tube to help release free ruminal gas. Also, mild agitation of ruminal contents can aid in the release of the trapped gas bubbles. Mineral or vegetable oils can be used as antifoaming agents and help release gas. Treatment with commercially available anti-bloating agents can also be done at this time.

“Some people will actually use a rumenotomy (puncturing the rumen-located high on the left side of the lumbar region in severe bloat cases) in severe, life-threatening situations. This procedure is not for the weak stomached, as the pressure will result in the expulsion of a significant amount of the rumen contents. Also, the area will need to be cleaned and sutured after the rumenotomy is performed.”

I would never wish any shepherd to experience the death of a beloved (or not so beloved) sheep from bloat. I hope that you never have to see what bloat looks like. But do try to recognize the symptoms of healthy ruminating sheep so that you are able to also recognize signs of ruminant distress. And keep on hand some remedies so that-should an emergency arrive-you can quickly react and hopefully save an animal.

Sources:

Henderson, David C., The Veterinary Book for Sheep Farmers. Farming Press, United Kingdom, 1990, pg 409-411.

Herrick, Dr. John B. Prescriptions for Healthy Farm Animals. A Farmer’s Digest Publication, Brookfield, WI. 1991, pg 99-101.

Kammlade, William G., Sheep Science. J.B. Lippincott Co., 1947, pg. 461.

Lawson, Laura. Detecting, Diagnosing, Treating Lamb Problems. LDF Publications, Culpeper, Virginia, pg 121.

Neary, Mike. “Preventing Pasture Bloat in Sheep” from Internet website of Purdue University, taken from the article that was originally published in The Working Border Collie, Inc., Jan/Feb. 1997.





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