Nutritional related sheep and goat diseases

The metabolic related diseases mostly occur during certain stages of pregnancy or with lactation, which help to differentiate them from other nutritional deficiencies.

 It is important to follow preventive management practices to minimize losses from potentially costly diseases.

Sheep and goats are exposed to diseases, but fewer would die if farmers recognized the problem, made the correct diagnosis, and treated them in the most effective manner. 

To make the correct diagnosis is very difficult as it requires experience. Consulting with a veterinarian can be most helpful. The following comments are intended to help diagnose, treat, and prevent some of the more prevalent nutritional health problems in sheep.

Pregnancy Disease

 Pregnancy disease is an upset or interference in the carbohydrate metabolism cycle and is not related in any way to the amount of exercise the ewe gets. In converting fatty acids and particularly body fat to glucose, ketones accumulate in the bloodstream and blood glucose levels decline. The ketones are very toxic to the ewe, resulting in death within two to five days.

Pregnancy disease occurs only among ewes carrying multiple fetuses and usually only during the last four to five weeks of gestation. The ewe stops eating, which reduces her source of carbohydrate. She separates from the flock, often wanders around aimlessly, and may press her head against the barn or feed bunk.

Unless a ewe is treated very soon after the first signs are noticed, little can be done. Separate her from the flock, drench her with 300 ml propylene glycol twice a day until she eats, and offer her grain and hay. Drenching with glucose, honey, or molasses or injecting 40-50 cc of 5-10 percent glucose under the skin can also be used with reasonable success. If the ewe is not treated on the first day, however, the prognosis is poor.

 

To prevent pregnancy disease, keep ewes gaining weight during the last four weeks of gestation. (Photo right)

Increase the energy intake by feeding under poor veld conditions, 250-500 g grain per ewe daily. Fat ewes may be more susceptible, because they have difficulty increasing in weight, have limited feed capacity in relation to their size, and have an abundant amount of fat to convert to energy.

Enterotoxemia (Overeating Disease)

 Enterotoxemia can kill sheep and goats of all ages but usually kills only those that consume high levels of carbohydrates. Feedlot mortality for vaccinated lambs is 0.5 %; for unvaccinated lambs it is 5 to 10%. 

Vaccination is the cornerstone to prevention of the disease.

Clostridium perfringens type D, one type of bacteria that causes Enterotoxemia, is most prevalent in feedlot or in creep-fed lambs. Symptoms are sudden death, occasional pushing, and staggering, and apparent blindness. For an outbreak, vaccinate with type D toxoid on day 1 and again 12 to 14 days later, deworm, and reduce grain until the vaccine takes effect.

C. perfringens type C causes a type of Enterotoxemia that usually is accompanied by bloody scours. Mortality may be high. It usually occurs among fast gaining lambs during the first three weeks. Ewes vaccinated three to four weeks before lambing, provide antibody protection in their milk. Normally, vaccine won’t “take” on young (3 to 10 days) lambs that are nursing.

Prevention of Enterotoxemia is far more likely to be successful than trying to treat the disease. Most commonly , the change in diet that triggers the diseases an increase in the amount of grain! Protein supplement and/or grass that the sheep or goat is ingesting.

Always make feed changes slowly.

Acidosis 

Overfeeding of highly fermentable carbohydrate diets may cause acidosis. The high grain intake lowers the rumen pH from about 6.5 + to below 5.5, at which point lactic acid production increases and causes acidosis. Ewes fattening on grain, lambs on protein-supplemented carbohydrates, rams being fed for show or any feedlot animals on a high starch diet are at risk. Affected animals discontinue eating and showing signs of severe stomach pain. Affected animals sometimes are very lame and prefer to lie down or walk on their carpi.

This is because, especially the front feet are hot and painful in the acute stage of acidosis. These symptoms are named laminitis and may lead to permanent hoof deformities. Affected animals are staggery initially and have bloated, distended rumens. Some may have acute, watery diarrhoea. Later they may become recumbent, cold and comatose with sunken eyes indicative of dehydration.

Animals experiencing acute acidosis should be treated immediately. Purging with mineral oil or a bicarbonate drench is effective. If an animal has symptoms of brain disorder an injection of thiamine (Vit. B1) should be administered. To prevent acidosis the following management tips should be followed:

·         Feed complete-mixed diets. Don’t feed

 grain and hay separately, if possible.

·         Minimise sorting of diet ingredients by the use

 of the same particle size for all feedstuffs.

·         Feed slowly fermenting grains (maize;

 grain sorghum) with rapidly fermented 

grains (barley; wheat; steam-flaked maize).

 Limit wheat to a maximum of 20 % of the diet

 if not accustomed to feeding wheat.

·         Gradually adapt animals to high-grain 

finishing diets in 21 to 28 days using three or

 four step-up diets. Suggested step-up diets may contain 45, 35, 25 and 15 % roughage.

·         Feed at least 15 to 20 % roughage (90% dry).  Roughage is similar to insurance.  The more roughage fed, the less likely acidosis will be a problem.  When acidosis is not a problem, feed efficiency and cost per gain increase as roughage level increases.

·         Make sure feed intake is consistent (not increasing or decreasing) before switching animals to the next diet.

·         Feed bunks should contain always a sprinkle of feed.  Never allow the animals to be without feed for more than 30 minutes.

·         Feed animals, as close as possible, at the same time each day.

·         Feed two or more times a day if possible.

·         Use an ionophore to increase feed efficiency and reduce variation in feed consumption.  (Ionophores are feed additives used in sheep  and cattle diets to increase feed efficiency and body weight gain).

·         Balance feedlot diets for 0.5 to 0.7 % calcium.

·         Keep daily records of dry matter feed intake.

·         Keep all water containers clean and fresh

·         Prevent urinary calculi in feedlot lambs by feeding ammonium chloride and/or ammonium sulphate at 1.0 % in the complete diet.

Feedlot Rectal Prolapse

Feedlot rectal prolapse occurs in 0 to 10 % of sheep.  This condition is caused by high grain diets, high feed intake, overweight, coughing, or a short dock.  There is no particularly effective cure.  Procedures usually include suturing the rectum partially shut or inserting a plastic tube or short piece of hose and clamping off the protruding position of the rectum with an elastrator ring.

Urinary Calculi

Urinary calculi occur in feedlot wether lambs and rams on high grain diets and in creep-fed wether

lambs.  Mortality is 80-90 % of those affected.  The usual cause is an improper calcium: phosphorus ratio.  High grain diets result in a Ca:P ratio of 1:2 or 1:3.  The ratio of Ca:P should be 1.5:1 or 2:1 thus, you must add limestone not dicalcium phosphate to fattening lamb diets. Another effective preventive measure is the addition of 0.75 to 1 % ammonium chloride to the grain diets.

Lamb Starvation

Lamb starvation, the number one killer of lambs, often associated with lack of shepherding.  Contributing causes are: 

·         The lamb doesn’t get started (gets no colostrum). Seventy-five percent of lambs that don’t get colostrum die for one reason or another.

·         The ewe won’t claim the lamb.

·         Mastitis.

·         The teat is too big or is too near the ground and the lamb doesn’t find it.

·         

Sore mouth.

·         The ewe can’t feed two lambs (mastitis, too little feed, etc.).

·         Joint injury or illness.

·         Pneumonia, which often is associated with lambs that received no colostrum and thereby lack immune bodies.

·         Difficult parturition.

·         A “genetic will to die”.  Actually, the majority of lambs die for no apparent reason.  A genetically caused lack of vitality may well be the cause.