Sheep

Behavior

Sheep are prey animals. As such, they rely on staying in a herd for safety and will flee as a herd from any perceived threat. Once a flock is moving, a sheep will instinctively follow the sheep in front of it.

Health and Care

As prey animals, sheep do not show signs of illness or pain readily, so it is important to pay close attention to detect changes in their behavior that may be indicators of disease or injury.

Teeth

In each year, for the first 4 years of their life, sheep will gain one set of permanent lower incisors, to replace their baby teeth. Therefore, you can count the sets of permanent incisors to estimate a sheep's age, as seen in the image below. After 4 years, sheep have a full, permanent set of lower teeth. Then as they age further, incisor teeth will start to spread, wear, and eventually break. Sheep do not have any incisors on their upper dental pad.

Figure 2: A sheep’s teeth as it ages (image from An Illustrated Guide to Sheep and Goat Production, Robert Armstrong).

Cast sheep

A sheep that has rolled onto their back is called a cast sheep. Cast sheep can become distressed and die within a short period of time if they do not roll back to standing on their own or are helped up. Heavily pregnant ewes, sheep with heavy, full fleeces, or short, stocky (or overweight) sheep are most prone to being cast.

Vaccines

Vaccines can prevent serious disease by stimulating the immune system with killed or modified versions of disease-causing microbes. Although there are many vaccines to choose from, not all will be appropriate for every farm. Close partnership with your veterinarian to determine a cost-effective and protective vaccine program for your individual herd is key.

It is usually recommended that you vaccinate ewes during late pregnancy for the clostridial diseases that most commonly affect lambs: Clostridium perfringens type C & D (overeating disease) and tetanus. By vaccinating the pregnant ewe, lambs acquire temporary, passive immunity when they drink the colostrum, the first milk produced by the ewe after lambing. After that, kids should be vaccinated and boostered per label directions at weaning in order to gain longer term immunity.

Internal parasites

There are many internal parasites such as coccidia, gastro-intestinal nematodes (worms), roundworms, tapeworms, and liver flukes that can impact sheep.

Coccidia

Coccidia (a protozoan internal parasite) is host-specific, and least 11 different species infect sheep, while none impact humans. Most sheep are exposed to coccidia at some point in their life and most are asymptomatic, because small and frequently repeated exposures can lead to immunity. Therefore, disease from coccidia is rare in adult sheep, but they can still spread the infection to other sheep. In particular, if young lambs without immunity are exposed, they may have signs of clinical disease.

Coccidia have a free-living stage when they live outside the animal as an oocyst and a parasitic stage when they live in the gut of the animal. Oocysts get shed in the feces of infected animals. Once in the soil, oocysts either are killed by sunlight, drying or freezing or they mature and become infectious. Coccidia gets spread when susceptible sheep eat the mature, infective oocysts in manure contaminated water or feed (pastures and/or hay or pellet feeding systems). If the sheep doesn’t have immunity, within 10 - 14 days of consumption the parasites multiply a million-fold in their guts and cause intestinal damage leading to nutritional deficiency for the animal.

The most common sign of coccidia is scours (diarrhea). Lambs will also appear lethargic and may lose weight. Sheep may also have a "pot-belly" look to them. Lambs with subclinical coccidiosis may not have any apparent symptoms, but they will still have reduced performance. Adults may show signs of coccidiosis with temporary diarrhea when stressed or moved to a new area with a new species of coccidia.

There is no vaccine for coccidiosis in sheep. To prevent clinical coccidiosis, a diet that meets energy, protein, and mineral requirements is essential. Maintaining good barn hygiene with manure management, or rotational grazing will help minimize the risk of infection in young animals. Prior to weaning, when there is an anticipated change in diet and stress from changing social structures and environments, a coccidiostat can be added to feed, mineral, water or milk replacer to help reduce the impact of coccidia. Coccidiostats should not be fed year-round and should only be used strategically. For animals who develop signs of clinical coccidiosis, a diagnosis can be made by submitting feces for a fecal floatation and McMasters. Treatment can be administered to individuals by drenching or to groups of animals in feed or water. You can consult your veterinarian for further prevention and treatment options and details.

Gastro-intestinal nematodes (worms)

Most gastro-intestinal nematodes cause diarrhea and poor absorption of nutrients. The barber pole worm, a blood sucking parasite, is a common internal worm for sheep in the US. The barber pole worm causes protein loss to the sheep, pale mucous membranes, especially in the lower eye lid, and bottle jaw, or swelling due to fluid buildup under the jaw. Using the FAMACHA© system (assessing the color of a sheep’s inner eyelid), as part of the Five Point Check©, helps detect anemia and indicate sheep that may need to be dewormed due to barber pole worm infection. The Five Point Check© is described more in the below section.

Gastro-intestinal nematodes are generally spread through the consumption of the infective stage which then multiply in the gut and cause intestinal damage and nutritional deficiency in the animal. Eggs are pooped out and can be spread to other susceptible animals, as seen in Figure 3 below. Parasites are host-specific and thus parasites that impact sheep won’t impact other species, like cows or poultry.

Figure 3: Internal parasite life cycle (image from An Illustrated Guide to Sheep and Goat Production, Robert Armstron).

Five Point Check © and parasite treatment

Clinically parasitized sheep can be detected by using the Five Point Check©. You can learn more about this scoring system here. Your whole flock should be contained in a pen and each sheep evaluated individually based on this scoring system and then treated based on how they score. The five conditions to check are: 1) FAMACHA© color scoring of inner eyelid 2) body condition score 3) Scour/dag/diarrhea score 4) bottle jaw score and 5) nasal discharge score. FAMACHA© and bottle jaw scores are a proxy for barber pole worm or liver fluke infection; body condition is an evaluation of all parasites; the diarrhea score can be a proxy for coccidia or brown stomach worm, among others; the nasal discharge score evaluates for nasal bot flies.

Typically, if a sheep scores 4 or 5 on the FAMACHA© color scoring, it is treated. If a sheep scores 3, the other scores from the Five Point Check are taken into account when deciding whether to treat or not. FAMACHA© scores of 1 and 2 are not treated. It is important to consider other factors such as lactation and feed conditions that may also impact body condition when using body condition score to make decisions. Sheep that repeatedly do not respond to worming treatment should be culled. FAMACHA© should only be used once properly trained, which can be completed through the University of Rhode Island here.

After determining that a sheep is clinically parasitized and needs treatment, it is recommended to give a combination treatment of dewormers of different classes (anthelmintics), due to the increasing resistance of worms to treatments. Dewormers are given orally as a "drench" via a syringe. Targeted selective treatment plans that only treat clinically parasitized sheep and use a combination of dewormers can help slow the development of worms that are resistant to dewormers.

General internal parasite control

Preventing parasite infection is challenging in sheep. Effective preventative strategies include mixed species grazing (cattle, swine, or poultry with sheep – not goats because sheep and goats share parasites) and not letting sheep graze forage shorter than 3 inches. While typical rotational grazing (with rest periods of 25 - 50 days) has benefits for animal performance and pasture quality, longer rotations are typically required to reduce parasite loads. These longer rest periods are not realistic in most irrigated pasture scenarios, so rotational grazing isn’t enough to prevent parasite infection in these scenarios. Finally, environmental conditions such as air temperature can impact parasite loads in soil, with days over 104°F in the summer or below 50°F in the winter greatly reducing parasite soil numbers, potentially helping with parasite control.

Housing and Fencing

Housing

Sheep require natural (trees, shrubs, terrain or rocks) or constructed shelters to escape the elements (sun, wind, etc). Shelters should have adequate ventilation and be of a size to accomodate the flock. Sheep may bunch and suffocate or overheat if they are seeking shelter in a space that is too small Sheep are herd animals and should not be housed alone.

Fencing

Sheep can be contained with temporary electric fence, either wires or netting, and moved in interior paddocks around a property. Adequate grounding and proper electric fence installation and maintenance are critical to containing sheep effectively. Do not put sheep in electric fence without turning it on. They will push through and learn to not respect the fence. Sheep may also push through electric fence if they have been left in one paddock for too long and feed is low. For more information on interior fencing, see the Sheep 201 page on fencing and check out our section on fencing on our Rangeland and Pasture Management page.

Having a good, permanent perimeter fence around your property is crucial, in case your sheep and other livestock gets out of your interior fences. For more information on perimeter fences, you can look at state regulations and county ordinances for perimeter fencing regulations and guidelines.

Figure 4: A sheep dog moves a ewe and her lamb in a temporary paddock fenced with electric fence netting that is within permanent perimeter fence. Photo/courtesy Dan Macon.

Nutrition

Water

Sheep need fresh, clean drinking water at all times. Water intake varies with ambient air temperature, diet, and stage of production, and will range from less than a gallon per sheep in the winter to 2 - 3 gallons in the summer.

Raising sheep on rangeland

Sheep are ruminants, so they need forage in their diet to keep their rumen functioning correctly. Sheep are grazers who prefer to eat forbs (broad-leaved plants) over grasses, but they will also eat grasses.

As seen in the three tables below, it is possible to time the increased nutritional needs during lambing and lactating with increased forage nutritional value by lambing in the spring (between Feb - Apr). However, other constraints may prevent this, so supplemental feed (irrigated pasture, hay, grain, silage etc.) is sometimes required to meet times of higher nutritional demands when otherwise relying on unirrigated rangeland. Dry rangeland can be utilized by sheep provided they are fed a protein supplement to aid in digesting dry grasses and forbs. You can learn more on our Rangeland and Pasture management page.

Table 1: Nutritional requirements of sheep.

Table 2: Nutritional supply from forage.

Figure 5: Matching feed requirements of lambing ewes and annual range/irrigated pasture availability. Figure from Sheep Management Basics- It all Starts With Grass UCANR Publication 31-1000

Reproductive Cycle

Most sheep breeds naturally have a seasonal reproductive cycle (short day breeders) and can only become pregnant in the fall. When day length becomes shorter, the ewe's brain releases hormones that start their estrus cycle. Estrus cycles are about 17 days long. Ewes will come into heat approximately every 17 days (until they become pregnant). Ewes will be in heat, or receptive to mating, for about 24 - 36 hours and this is the only time a ewe will allow a ram to mate with her.

Some sheep breeds developed in the tropics or nearer to the equator, such as Dorset, Rambouillet, Polypay, Karakul, Merino, Finn, and hair sheep, are less likely to display seasonal breeding patterns.

Flushing is the practice of providing extra nutrition (as grain, alfalfa or high quality pasture) to ewes 2 - 3 weeks before breeding season and continuing 2 - 4 weeks into breeding season. The increase in body condition due to flushing usually increases conception and twinning rates.

A ewe is pregnant for about 5 months, or 142 - 152 days. Ewes usually give birth to 1 - 3 lambs during lambing. Newborn lambs from medium to small breeds weigh between 5 and 12 pounds with an average of about 9 pounds. Ewes are usually bred until they are about 7 years old before their productivity declines. Rams are typically replaced after 2 - 3 years to avoid inbreeding.

Culling is selecting livestock to remove from your herd for various reasons such as age, problematic disposition, bad feet, poor health, or infertility. Culling can also be one practice used to remove ewes that have production traits that are not desirable for your operation's goals (ex: either too many or too few lambs, too big or too small lambs, poor wool quality, etc). Culled animals may be sold directly to slaughter, through a livestock auction, or to a new owner after clearing withdrawal periods if they received any medications.