Lamb

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Key Facts

  • On average, Americans consume less than a pound of lamb per year, compared to an average of 85 pounds of beef per capita annually.
  • About 80 percent of lamb comes from farms with more than 100 sheep.
  • Demand for lamb usually increases around major holidays, as it is a common holiday dish for Christians, Jews, and Muslims.
  • Latinos and Muslims consume the most lamb per capita in the U.S.
  • Between 1998 and 2017, at least 23 lamb-associated outbreaks were reported to CDC’s National Outbreak Reporting System (NORS), causing 330 illnesses, 49 hospitalizations, and no deaths. The most commonly implicated pathogens were Salmonella enterica and Shiga-toxin producing Escherichia coli.
  • Like other meats, lamb has a high risk of contamination due to the slaughter process, where there is greater opportunity for infected animal intestines or feces to come in contact with lamb carcasses.

Introduction

Lamb meat comes from domesticated sheep (Ovis aries), which have been raised by humans for longer than any other domesticated meat species, beginning in the Middle East about 9,000 years ago. In many countries, lamb is the primary source of dietary protein, and it is packed with vitamins and minerals. Like other red meats, the protein lamb supplies is nutritionally complete, containing the nine essential amino acids, but unlike the other red meats, lamb contains very little fat and, therefore, has fewer calories per serving.

All products made from lamb meat are considered “lamb” in the U.S., which is not the case for many other countries, where products must be specifically labelled as either mutton (meat from adult sheep), hogget (meat from juvenile sheep older than one year), or lamb (meat from a sheep in its first year). Lamb meat is naturally tender and mild in flavor, while mutton has a more intense flavor that is preferred in some cultures. Typically, sheep are brought to market at six to eight months old, weighing approximately 140 pounds and yielding about 46–49 pounds of edible meat.

Many sheep on a farm
Sheep farm

In 2017, the Census of Agriculture counted 5.32 million sheep on approximately 84,000 sheep farms in the U.S., with Texas and California raising the most sheep. About 80 percent of these sheep come from farms with over 100 sheep; however, small farms (less than 100 sheep) make up the majority of sheep operations in the U.S. This may be because sheep are relatively simple animals to raise and can easily boost the profits of a small family farm. The U.S. imports about 140 million pounds of lamb every year and exports only a very small amount.

Foodborne Outbreaks

Between 1998 and 2017, at least 23 lamb-associated outbreaks were reported to CDC’s National Outbreak Reporting System (NORS), causing 330 illnesses, 49 hospitalizations, and no deaths. In outbreaks with known etiology, the most commonly implicated pathogens were Salmonella enterica (40%) and Shiga-toxin producing Escherichia coli (40%) but have also included Bacillus cereus (13%), norovirus (7%), and Staphylococcus aureus (7%). Compared with other meats consumed in the U.S., this is a relatively low number of outbreaks. During the same time interval, chicken and beef were associated with 1,416 and 1,039 outbreaks, respectively. These differences may be due to the low consumption per capita of lamb in the U.S. compared to other meats.

Below are examples of outbreaks and recalls associated with lamb reflecting the diversity of vehicles, pathogens, and other circumstances:

In 1995, contaminated minced lamb kebabs and yogurt dressings purchased from two takeaway restaurants sickened 52 individuals (6 hospitalizations; no deaths) with Salmonella enterica serotype Typhimurium in South Wales. The restaurants obtained minced lamb and yogurt from the same wholesaler. Upon inspection, the wholesale premises were found to be dirty and structurally unsuitable. Yogurt containers were unsealed and stored directly beneath lamb carcasses. Some yogurt containers were visibly contaminated with blood. Environmental samples and a minced lamb sample obtained from the wholesaler tested positive for Salmonella. The lamb used in kebabs sold by the two restaurants may have been contaminated and served undercooked, or the kebabs may have been cross-contaminated with the yogurt dressing.

In 2005, contaminated lambs’ liver sickened at least 37 individuals with Salmonella enterica serotype Typhimurium New South Wales. Cases reported eating the livers both cooked and raw. Over half of the cases were of Lebanese descent and one seemingly unrelated case was the child of a slaughterhouse worker. The livers were purchased from two different butchers and traceback revealed that a single slaughterhouse supplied them both with liver. Samples taken from both butchers and the slaughterhouse tested negative for Salmonella. Consumption of contaminated liver or cross-contamination in the home during preparation were identified as likely routes of transmission.

In 2006, contaminated lamb kibbe, a Middle Eastern dish, sickened 8 individuals (1 developed HUS) with Escherichia coli O157:H7 in Ohio. Five of the ill individuals purchased or had family members that purchased raw lamb from the same Middle Eastern meat market in Toledo, Ohio. Cross-contamination with beef at the meat market was identified as a likely route of transmission.

In 2015, contaminated foods purchased from butchers, including raw lamb burgers, sickened 15 individuals (10 hospitalizations; 7 developed HUS) with Shiga-toxin producing Escherichia coli O157:H7 in northeast England. The implicated pathogen was detected in raw lamb burger samples obtained from a single butcher and was genetically similar to bacterial isolates obtained from fecal samples of cattle supplied to the implicated butchers. Cross-contamination at the butcher shops was identified as the likely route of transmission.

In 2016, PT Farm, LLC of New Hampshire voluntarily recalled 15lbs of lamb products due to potential contamination with Escherichia coli. The recall was initiated after the establishment received a boil water notice from the North Haverhill Municipality Water Department in response to a positive E. coli water sample.

In 2017, over 400 lamb carcasses were condemned at meat plants in Ireland due to Sarcocystis parasitic infection. There was no indication that any contaminated meat was ever available for sale to consumers, in Ireland or abroad. The infected carcasses were believed to have originated from a single flock in Co Donegal, Ireland. There were no reported human illnesses.

In 2017-2018, contaminated lamb and mutton sickened nearly 300 individuals (1 death) with Salmonella enteria serotype Typhimurium in England, Wales, and Scotland. Consumption of contaminated meat or cross-contamination with contaminated meat were identified as likely routes of transmission. No single farm or slaughterhouse was identified as the source.

Production

Lambs are nursed by their mothers until they are weaned, about 60 days after birth, when they gradually move to a diet of pasture, hay, or coarse grains such as corn, barley, milo, and supplemented wheat. Antibiotics may be given to sheep to either prevent or treat disease, and hormones may be used to promote growth; however, a sufficient period of time between administration of antibiotics or hormones and slaughter is required in the U.S., so that any residues can exit the body. Tests for residues are performed by the FSIS, and violations are investigated by the U.S. Food and Drug Administration (FDA) or the state department of agriculture.

Lamb being fed by sheep
Lambs feeding before they are weaned.

When slaughtered, a sheep is first stunned, either mechanically (a bolt is fired through the skull) or electrically, to ensure a humane death. After stunning, the sheep is usually then suspended by a hind leg and moved down a conveyor line to be “fisted”, a process for removing the pelt. Next, the animal is bled, the feet are removed from the body, and the head is removed at the first cervical vertebra. The carcass is then refrigerated at a temperature between 30 ºF to 32 ºF for at least twenty-four hours, but no more than ten to fifteen days, before being cut. The carcass is cooled before cutting to dry out any moisture on its surface. Eliminating moisture prevents rapid bacterial growth on the surface that can potentially contaminate the inside of meat when cut.

All lamb meat sold in the U.S. must undergo inspection, which is administered through the FSIS and occurs in several steps: antemortem inspection, postmortem inspection, and reinspection. Antemortem inspection identifies sheep not fit for human consumption, including sheep that are disabled, diseased, or dead. In addition, antemortem inspection separates healthy sheep from sheep showing signs of illness, who will then be inspected more thoroughly. Postmortem inspection identifies entire carcasses, individual parts, or organs that are not fit for human consumption. Reinspection during processing makes sure that the ingredients used in the manufacturing of lamb meat, such as spices in ground lamb meat, are safe to consume. After reinspection, grading may be done to determine the quality of the meat, based on desirable traits such as tenderness and flavor. Grading is mainly based on the age of the sheep at the time of slaughter and has no implication on the safety of the meat.

It is essential that any raw or partially pre-cooked lamb packages includes safe handling instructions, detailing how the consumer should safely store, prepare, and handle the raw meat.

Food Safety

Contaminated meat and meat products from small ruminants, such as sheep, can transmit the bacteria Clostridium perfringens, Staphylococcus aureus, Cryptosporidium parvum, Shiga-toxin producing Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogenes, Brucella, Salmonella, and Bacillus anthracis as well as the parasites Toxoplasma gondii, Echinococcus granulosus, Giardia duodenalis, and Fasciola.

One study conducted in 1998-1999 among lamb samples collected from six geographically dispersed U.S. packing plants found the incidence of Salmonella and Campylobacter to be 1.5% and 0.3%, respectively. Another study that sought to estimate the risk of human illness associated with various meat commodities in the U.S. found that, following beef, lamb has the second highest per serving risk of Escherichia coli O157:H7. In the United Kingdom, a study conducted in 1997-1998 isolated Escherichia coli O157 from 1.4% of sheep fecal samples and 0.7% of lamb carcasses collected in South Yorkshire, England. Salmonella was isolated from 0.1% of fecal samples collected from sheep at slaughterhouses in England from 1999-2000. Among sheep meat samples collected in Iceland, Shiga-toxin producing Escherichia coli was detected in 30%. Among lambs sent for slaughter in 2018 in Ireland, 15% were condemned due to the presence of lesions in muscle tissue. Testing indicated Taenia ovis and Sarcocystis parasites.  A 2004 study of sheep carcasses and frozen boneless sheep meat obtained from Australian slaughterhouses isolated Escherichia coli O157:H7 from 0.6% of carcasses and 0.2% of meat samples. Salmonella was isolated from no carcasses and 0.5% of meat samples. Campylobacter was isolated from 0.4% of carcasses and 0.2% of meat samples. Coagulase positive staphylococci were isolated from 15.9% of carcasses and 14.1% of meat samples.

For consumers to avoid illness and cross-contamination, raw lamb or mutton should be selected immediately before checking out at the register and placed in a plastic bag, if available. Doing so will help to contain any leakage and limit the time that the meat is not refrigerated. Lamb should be refrigerated immediately at 40ºF or below and consumed within 3-5 days, or frozen at 0ºF or below. Cooked or ready-to-eat lamb or mutton products should be consumed within 2 hours or refrigerated at 40ºF or below. Cooked products should be consumed within 3-4 days and reheated to an internal temperature of 165ºF.

Lamb and mutton can be safely thawed in the refrigerator, by submerging in cold water, and by microwaving. Do not thaw products at room temperature. Lamb patties, ground lamb mixtures, and organ meats (such as liver) should be cooked to an internal temperature of 160ºF. Lamb steaks, chops, and roasts should be cooked to an internal temperature of 145ºF.

A lamb roast

Consumption

A lamb gyro on a colorful ceramic dish
Lamb gyros are a popular Greek food in the U.S.

Lamb is not as popular in the U.S. as it is in other countries. In fact, the per capita consumption of lamb in the U.S. has declined from 5 pounds in the 1960s to less than one pound today. In 2019, the U.S. consumed only 0.8 pounds per capita of lamb meat. The same year, Kazakhstan consumed the most lamb per capita in the world at 18.1 pounds, followed by Australia with 13.7 pounds, and Norway with 9.9 pounds.

In the U.S., the largest consumers of lamb are Latinos and Muslims, whose populations are increasing. Lamb producers have begun to target cities with large Muslim populations, such as Detroit and Chicago, with Halal lamb (meat prepared according to Islamic laws). Demand for lamb usually increases around major holidays, and lamb is a common dish for Muslim celebrations, such as Eid al-adha (the Festival of Sacrifice), which involves sharing a lamb meal among family, friends, and the poor.

Nutrition

Lamb is an excellent source of protein, vitamins and minerals, and is especially high in B vitamins, zinc, and iron. Because lamb meat contains significantly less fat compared to other red meats, and has zero carbohydrates, it is a lean and heart-healthy choice. Three ounces of lamb, a typical serving size, covers 43 percent of a male adult’s recommended daily allowance of protein and only seven percent of the recommended daily caloric intake. While there are a lack of large-scale studies confirming the direct health benefits of lamb consumption, lamb is a common meat in Mediterranean diets, which have consistently been shown to decrease risk of cardiovascular disease. In addition, a 2013 study found that grass-fed lamb meat has 14 percent less fat and eight percent more protein than grain-fed lamb, making it the healthier option for consumers.

References

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Authors

Talitha Anderson

Talitha Anderson

BS Public Health Student; University of Washington

Kathleen Conery

Kathleen Conery

MPH One Health; University of Washington

Maayan Simckes

Maayan Simckes

PhD Epidemiology; University of Washington

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