NC State Extension Publications

 

Sheep is a term for selective grazing animals that may be domesticated (tamed) or wild. This material will primarily focus on domesticated sheep. Behaviorally, sheep are gregarious, precocial, defenseless creatures. But what does that mean? Gregarious means that they flock together or like to be with a group. It is rare to see a sheep by itself because of their gregarious nature. Precocial means that they have a high degree of independence at birth. This means that they can stand on their feet shortly after birth. Sheep are defenseless for the most part against predators like coyotes and wild dogs. Sheep are also very selective in their grazing habits. Sheep have a split in their upper lip, with this they are able to pick the preferred leaves off of the plant.

At one time all sheep were wild. Around 10,000 BC sheep were domesticated by the humans. Most of the wool breeds of sheep were developed from Moulfan sheep. Most of the hair breeds are similar to the Urial sheep of ancient times. Prior to domesticating sheep, the dog and reindeer were domesticated.

As the animals were raised under tamed conditions, they went through several changes. On the outside the sheep began to develop more wool and less hair. The color of the wool and hair changed from brown and shades of brown to whites and blacks. Their ears became more of a lop ear than an erect ear. The horns that the wild sheep possessed were weakened and disappeared from many breeds. On the inside the sheep changed as well. These internal changes happened at both ends. The tails had less vertebrates, or bones than the sheep do now. Today's sheep also have a smaller brain than the sheep 12,000 years ago.

Sheep were tamed for several uses that still apply today. The sheep were first used for meat, skins, milk and wool. Sheep are still used for these basic purposes plus many more. Sheep by-products are in many items that we use everyday.

Sheep Facts


Animal Profile
Classification Scientific Name Common Term
Kingdom Animalia animal
Phylum Cordata vertebrates
Class Mammalia suckle young
Order Ungulata hoofed mammals
Sub-Order Artiodactyla even toed Ungulata
Section Pecora typical ruminants
Family Bovidae hollow horned ruminants
Subfamily Caprinac sheep and goats
Genus Ovis sheep
Species Ovis Aries domesticated sheep

Sheep Terms
Ram male of breeding age
Wether castrated male
Ram lamb immature male
Ewe lamb immature female
Lamb newborn
Flock group (3 or more)
Tupping act of breeding
Lambing act of parturition (giving birth)
Birth weight 5 - 8 lb.
Average number born 1.1 - 1.4 lambs/year
Weaning age 2 - 3 months
Pasture carrying capacity 5- 6 ewes and lambs/acre

Types of Sheep (body covering)
Fine wool Merino (100%)
Medium wool 14, 38, 12 blood
Long wool coarse, strong, luster, 12"/year (English breeds)
Carpet wool lowest quality
Hair straight, non elastic and glossy

Biological Traits
Temperature (°F) Respiration rate Pulse rate
Maximum 104.0 20 80
Average 102.5 16 75
Minimum 102.0 10 70

Life span: 6 -11 years

Chromosome number: 54


Digestive System
Ruminant multiple-compartment stomach containing microbes (bugs) that are able to digest forages
Daily consumption levels Food: 2 - 4.5 lbs
Water: 0.5 - 1.5 quarts
Daily waste volume Fecal: 2 - 6.5 lbs
Urine: 10 - 40 ml per kg of body weight

Reproductive Traits
Ewes
Mature weight 90 - 300 lbs
Breeding season early fall to late winter (some are poly-estrous year round, ex. Dorset)
Estrous cycle 14-19 days seasonally poly-estrous
Duration of estrous 24 - 26 hours (standing heat)
Time of ovulation 24-30 hours from beginning of estrous
Gestation period 145 - 155 days
Breeding/year 1 - 2/year
Artificial insemination Yes, cervical or vaginal method
Intrauterine method
Ewe lambs
Puberty 5 - 8 months (80-100 lbs)
Minimum breeding age 8 - 10 months
Rams
Puberty 6 - 8 months
Mature weight 150 - 450 lbs
Serviceability 1 ram: 30 - 35 ewes (60 day breeding season)
Ejaculate volume 0.8 - 1.2 ml
Sperm concentration 2,000 - 3,000 million/ml
Motile sperm 60 - 80 %
Semen freezable yes

Under the Hide (Carcass Information)
High Average Low
Age at slaughter 8 months 6 months 4 months
Live weight 160 lbs 125 lbs 85 lbs
Dressing percentage (%) 57% 52% 45%
Fat thickness .50 in .25 in .05 in
Kidney, pelvic, and heart fat (% KPH) 6.0% 3.0% 1.5%

Yield Grades

1, 2, 3, 4 & 5, based on the backfat thickness at the 12th rib

yield grade formula = 0.4 + (10 x adjusted back fat thickness, inches)

Quality Grades

Based on a composite evaluation of conformation, maturity, and quality of the lean flesh

  • US Prime
  • US Choice
  • US Good
  • US Utility

Degrees of flank fat streaking - used to predict marbling, since lamb carcasses are not ribbed to expose ribeye muscle marbling

  • Devoid
  • Practically devoid
  • Traces
  • Slight
  • Small
  • Modest
  • Moderate
  • Slightly abundant
  • Moderately abundant
  • Abundant

Maturity (physiological) - Chronological age of the live lamb is determined by assessing the physiological age of the bone and muscle. Maturity grades are A and B.

Break joint (young lambs) - the rigid surface of the joint is quite red, moist, and porous

Spool joint (older sheep) - the joints become drier and harder

Color of lean - red to dark red

Sheep Teeth

  • 20 temporary teeth
  • 32 permanent teeth at maturity
  • 4 pairs of incisor teeth on lower jaw
  • upper incisors missing
  • cartilaginous (hard) dental pad on upper jaw
  • split upper lip with mobile lips

Age of Sheep (teeth)
Lamb 4 pair of incisors
1 year middle pair of incisors
2 years 2nd pair of permanent incisors
3 years 3rd pair of permanent incisors
4 years 4th pair of permanent incisors
5 years all permanent incisors close together
6 years incisors begin spreading apart
7-8 years some incisors broken
10-12 years all incisors missing

Sheep teeth diagram by year.

Sheep teeth diagram by year.

Authors

Extension Livestock Specialist
Animal Science
Extension Livestock Technician
Animal Science

Publication date: March 24, 2003

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.