NAHMS (National Animal Health Monitoring System)

NAHMS Sheep 2011 Study

The NAHMS Sheep 2011 study was conducted in 22 of the Nation’s major sheepproducing States. The study provides participants, stakeholders, and the industry with valuable information representing 70.1 percent of U.S. farms with ewes and 85.5 percent of the U.S. ewe inventory (NASS 2007 Census of Agriculture).

Part 1: Reference of Sheep Management Practices in the United States, 2011

Items of Note

Population estimates and operator experience

Sheep breeds in the United States can be categorized by purpose, fi ber type, and face color. Black- or nonwhite-faced breeds include Suffolk, Hampshire, Shropshire, Oxford, and Southdown. These breeds are often considered meat producers, while white-faced breeds are more often used for wool production. Because each sheep breed offers superiority in some trait, producers often blend the breeds to gain the superior characteristics of each breed in offspring. These offspring are used to attain the phenotypic requirements of their operation’s type and geographical conditions. While the highest percentage of operations (44.7 percent) had black-faced wool breeds, the highest percentage of sheep and lambs (41.7 percent) were in the white-faced breed category. Sheep are a multiuse species. For example, 81.6 percent of operations raised sheep for meat, 26.5 percent for seed or breeding stock, 15.8 percent for wool, and nearly 32.6 percent of operations raised sheep for more than one reason. When rapid means of communication with producers is important, it can be helpful to work with national or State industry organizations to promulgate necessary information. Over one-fifth of producers (22.9 percent) belonged to a national sheep organization, and almost one-third (29.0 percent) belonged to a State or local sheep industry association or club. These percentages vary by size of operation and by operation type.


Flock and individual animal identifi cation (ID) are important tools used to reduce disease and increase productivity on U.S. sheep operations. Almost 9 of 10 operations (88.6 percent) used some form of individual ID for their sheep. The most commonly used form of either individual or fl ock ID was the free Scrapie Program ear tag.

Lambing management

With the increase of smaller operations, nontraditional marketing methods, and improved reproductive techniques, more operations have the ability to lamb during the season that best suits their customers’ needs. The highest percentage of lambs were born from February through May, which allows producers to make the most use of available forage. Spring lambing also coincides with natural breeding and lambing seasons, when ewes are likely to produce larger lamb crops. For operations that managed their sheep primarily on the open range, docking may be the fi rst time they view the sheep after lambing. At this time, lambs are tagged, castrated, docked, and vaccinated, and ewes are examined to ensure health and fecundity. Overall, 80.5 percent of lambs born alive were docked. Nearly 7 of 10 operations castrated ram lambs at an average age of 23.4 days, and more than 3 of 10 operations castrated ram lambs in the fi rst 7 days of age.

Part II: Reference of Marketing and Death Loss on U.S. Sheep Operations, 2011

Items of Note

Lamb marketing

The largest marketing component of the sheep industry is the sale of lambs. Overall, the majority of sheep operations with 20 or more ewes (52.5 percent) sold their lambs at auction markets or sale barns. Large operations (500 or more ewes) are the exception. Marketing on large operations is more diverse compared with the other operation sizes. For example, a relatively equal percentage of large operations sold lambs directly to slaughter (24.4 percent), directly to feedlots (20.8 percent), at auction or sale barns (29.6 percent), or directly to buyer/dealers (29.0 percent). Marketing characteristics also varied by region. In the Central and East regions the majority of operations sold lambs at auction or sale barns (58.0 and 52.0 percent, respectively), while in the West region similar percentages of operations sold lambs directly to consumers (25.1 percent), directly to another operation (21.3 percent), at auction or sale barn (22.5 percent), and directly to buyer/dealers (23.2 percent). Not surprisingly, lamb marketing also varied by flock type. The majority of fenced-range (59.4 percent), pasture (51.3 percent), and dry lot/feedlot (51.8 percent) operations sold lambs at auctions or sale barns, while similar percentages of herded/open-range operations sold lambs directly to slaughter (22.9 percent), directly to feedlots (27.2 percent), and directly to buyer/dealers (25.3 percent). Overall, 75.3 percent of lambs were sold in the United States during 2010. Of those, 27.3 percent were sold at auction/sale barn, 24.9 percent were sold directly to slaughter, and 17.3 percent were sold directly to buyer/dealers. For all operations, the majority of cull sheep sold (60.4 percent) were sold at auction markets or sale barns. The majority of breeding and “other” sheep (51.7 percent) were sold directly to another operation. The primary reason for culling rams and ewes was old age. The average age at which rams and ewes were culled was 4.9 and 6.3 years, respectively. Rams and ewes on large operations were slightly older when culled than those on smaller operations.

Death losses

Predator losses have a substantial economic impact on U.S. sheep operations. Overall, coyotes caused the highest percentage of predator losses (51.8 percent), but predator predominance varies by geographic location, fl ock size, and fl ock type. For example, mountain lions, cougars, or pumas were a cause of sheep loss on 26.8 percent of operations in the West region but on only 1.3 percent of operations in the East region. Dogs were a cause of sheep loss on 39.3 percent of very small operations (fewer than 20 ewes), while only 4.1 percent of large operations reported predation due to dogs. Death-loss evaluations in 1994, 1999, 2004, and 2009 have shown lamb death loss ranged from 9.5 to 10.8 percent of lambs born. In 2010, lamb death loss for all operations was 11.2 percent of lambs born. In 1994, 1999, 2004, and 2009, sheep death loss ranged from 5.6 to 6.5 percent. In 2010, sheep death loss for all operations was 5.0 percent of adult sheep inventory on January 1, 2011. Predator losses were highest in the Central region, where 37.9 percent of operations lost lambs and 22.5 percent lost sheep due to predation in 2010. Nonpredator losses accounted for 3.8 percent of sheep lost on 47.2 percent of all operations during 2010.

Veterinary use

Almost one-fourth of operations (23.9 percent) had a private veterinarian visit for any sheep-related reason during 2010. For operations that did not use a veterinarian during 2010, 68.9 percent indicated they had no health-related problems; 5.1 percent reported there was no veterinarian with sheep experience available; and 11.8 percent claimed veterinarian visits were too expensive.

Sheep shearing

Overall, 80.2 percent of operations with 20 or more ewes sheared lambs and sheep during 2010. A hired individual was used to shear sheep on 50.9 percent of these operations, while 29.2 percent contracted with a shearing crew, and 26.2 percent used employees or the sheep owner to shear.

Part III: Health and Management Practices on U.S. Sheep Operations, 2001

Items of Note

Flock additions

Producers sometimes inadvertently bring disease onto their operations by adding new animals to their flock. About one-third of U.S. sheep producers minimized their risk of acquiring new disease in their flock by not adding new animals, other than by natural birth. The longer an operation goes without adding animals, the higher the certainty that no asymptomatic, but infected, animals exist in the flock. Operations that did not add sheep during 2010 were considered “closed” flocks. On average, rams had not been added to closed flocks for 3.7 years, while ewes and lambs had not been added to closed flocks for 9.0 and 8.4 years, respectively.

Reproduction management

An accurate annual estimate of the actual lamb crop is an important measurement of flock productivity. Nearly all operations can provide their lambing rate, but it is not always clear how the rate is measured. For some operations in the largest lamb producing States (especially range flocks), the predocking period is an enigma. Therefore, their lambing rate is based on the number of lambs docked divided by the number of ewes bred. This method has its limitations. For these operations, the entire period from lambing to docking cannot be examined to determine whether the majority of lambs are lost to predators, a lack of colostrum, poor mothering, scours, pneumonia, or other causes. Losses are difficult to prevent if the cause of loss remains unknown.

Nearly half of all operations (47.3 percent) calculated the lambing rate by determining the number of lambs born divided by ewes bred. Over half of large operations (54.9 percent) determined lambing rate by estimating the number of lambs docked divided by the number of ewes bred. The producer-expected lambing percentage overall was 1.50. Small and medium operations had a higher expected lambing rate (1.53 and 1.47, respectively) than large operations (1.23).

Controlled internal drug release (CIDR) devices were approved for use in the United States in 2009. Overall, 6.7 percent of operations used CIDRs in 2010, and 95.6 percent of these operations would use them again. Three-fourths of operations that used CIDRs used them for out-of-season breeding.

Placentas can harbor infectious organisms and should be removed as soon after lambing as possible. Removing placentas is especially important on high-density operations in which ewes are clustered and exposure to placental organisms is high. In general, 67.9 percent of operations usually removed placentas from the lambing area. Composting and throwing out for carnivores were the two most common methods for disposing of placentas (30.8 and 28.0 percent of operations that removed placentas, respectively).

Diseases and control methods

Nearly all operations (92.0 percent) had an APHIS-assigned flock identification number. Overall, producers on 84.8 percent of operations were either very or somewhat familiar with scrapie. Of these, about half (47.3 percent) implemented genetic selection for scrapie control, and of these almost all (98.8 percent) used replacement rams genetically less susceptible (RR alleles) to scrapie.

Toxoplasmosis and coxiellosis (Q fever) are common causes of abortion storms in sheep flocks, yet producers on 28.5 and 52.0 percent of operations had not heard of toxoplasmosis and Q fever, respectively.

Vaccines can reduce the prevalence or severity of disease and are an integral part of any flock management program. Overall, 81.6 percent of operations used vaccines in 2010. The highest percentage of operations vaccinated against enterotoxemia and tetanus (71.4 and 64.5 percent of operations, respectively). A higher percentage of herded/open range flocks vaccinated for sore mouth compared with other flock types. Because the sore mouth vaccine is comprised of live virus, vaccinating against sore mouth is only recommended when a flock is already infected with the virus. The highest percentage of operations that vaccinated for sore mouth (70.6 percent) used a commercially available sore mouth vaccine.

Antibiotic use

Record keeping is an essential part of responsible antibiotic use. Records should include the name of the antibiotic used, animals treated, date treated, and reason(s) for treatment. During 2010, 69.0 percent of operations administered oral, injectable, or topical antibiotics to lambs or ewes to treat any disease. Just over half of operations that administered antibiotics (51.0 percent) kept antibiotic-usage records. The most commonly treated illness on sheep operations was respiratory disease; for operations that gave any antibiotics, 67.7 percent treated sheep for this illness during 2010. The antibiotic class used most frequently to treat respiratory disease was penicillin (29.9 percent of operations), followed by tetracycline (19.2 percent) and florfenicol (13.6 percent).

NAHMA Sheep 2001 Study

Part I: Reference of Sheep Management in the United States, 2001

This 88-page report contains results from NAHMS’ second national sheep study and was designed to provide both participants and the industry with information the U.S. sheep flock on operations with one or more sheep.

The table of contents includes the following sections:

  • Inventory
  • Flock Management and Breeding Practices
  • Reproductive Outcomes
  • Lamb Management and Productivity
  • Marketing
  • Death Loss
  • Cause of Loss – All Flocks
  • Carcass Disposal
  • Management of Sheep and Lambs on Feed
  • Grazing and Sheep Movement Biosecurity
  • Shearing
  • Wool Management
  • External parasite Treatment

Part II: Reference of Sheep Health in the United States

This 128-page report contains results from a nation-wide APHIS study, conducted in 2001. The table of contents includes the following sections:

  • General Management
  • Reproduction Management
  • Lambing Management
  • Health Management
  • Parasites and Deworming
  • Pasture Management
  • Feeding Practices

Part III: Lambing Practices, Spring 2001

This 42-page report contains results from the nation-wide APHIS study, conducted in 2001. The table of contents includes the following sections:

  • Population Estimates
  • Breeding and Lambing Management

Highlights of NAHMS Sheep 2001: Parts II and III

This 2-page summary of the aforementioned reports contains the major findings of each. Reports II and III should be reviewed if further detail is required.