Grassfed lamb and goat
Since this article was written in 2005, USDA-AMS has published voluntary standards for grass-fed livestock and the meat products derived from them. The new standards can be accessed from USDA AMS. The standards state that grass and/or forage shall be the feed source consumed for the lifetime of the ruminant animal, with the exception of milk consumed prior to weaning. The diet shall be derived solely from forage, and animals cannot be fed grain or grain by-products and must have continuous access.
Most sheep and goat producers maintain their breeding animals on pasture, browse, or range for the majority of the year, but the manner in which lambs and kids are fed for market varies.
"Grass-fed" is fast becoming a buzzword in livestock production and agricultural marketing. While USDA has defined what organic livestock production is and what it takes to meet labeling requirements, there is no official definition for "grass-fed." Not yet (see above).
The American Grassfed Association defines grass-fed products from ruminants, including cattle, bison, goats, and sheep, as "those food products from animals that have eaten nothing but their mother's milk and fresh grass or grass-type hay from their birth until harvest." No grain feeding is allowed. For non-ruminants, such as pigs and chickens, "grass should be a large part of their diets," according to the American Grassfed Association.
Creating a label for grass-fed is proving to be very controversial. This is because people have different interpretations of what grass-fed should be. The standards that USDA originally proposed for a "grass-fed" label stipulated that at least 80% of the ruminant's primary energy source be composed of grass, range, pasture, or other forage. "Purists" oppose this definition because it would allow short-term feeding of animals in feed lots or feeding supplemental grain to grazing livestock.
I don't know what the exact definition should be, but I tend to favor some grain feeding of livestock on pasture, if that is the producer's preference. Grain feeding tends to improve rate of gain and parasite tolerance in small ruminants. Giving lambs and/or kids a little bit of grain each day gives the producer a chance to more easily monitor the health and condition of his animals. Grain can be a very economical source of nutrients for growing lambs and kids.
Grain-fed lambs and kids usually bring a higher price at auctions because they tend to carry a higher degree of body condition. Yet feeding a little bit of grain on pasture is significantly different from confining livetstock to a feed lot and feeding them limitless grain.
Advocates for grass-fed products are quick to point out the numerous health benefits that can be obtained from grass feeding livestock. According to various research studies, the meat and milk from grass-fed ruminants contains more conjugated lineolic acid (CLA), vitamin E, omega-3 fatty acids, beta-carotene, and vitamin A than the meat and milk from grain-fed animals.
CLA and omega-3 fatty acids are good fats with anti-cancer, anti-diabetes, and anti-fat properties. The improved nutritional profile of grass-fed meat and milk may enable some producers to command a premium price for their products if they direct market them to consumers, restaurants, and specialty food stores/chains.
Of course, it's important to point out that raising livestock on pasture isn't the only way to affect the fatty acid composition of meat and milk. You can increase the amount of polyunsaturated fat and CLA in ruminant products by manipulating the fat source(s) in the animals' diet.
Supplementing a lamb, kid, or calf's diet with fish or plant oils (sunflower, corn, soybean, canola, peanut, or linseed) will have a similar effect as turning the animals out to pasture. There are also considerable differences in the CLA content of the meat and milk of animals consuming the same diet.
A New Zealand study showed that lambs nursing dams with high CLA content in their milk had 37% more CLA in their meat than those lambs whose dams had low CLA levels. Single lambs had 35% more CLA in their meat than twin-born lambs. A study conducted with beef cattle in Missouri showed that supplementing cattle with a mixed grain ration (up to 1% body weight) on pasture did not depress CLA levels in finished beef. Differences among and between breeds may ultimately allow for genetic selection to enhance the CLA content of ruminant products.
CLA is produced naturally by the microflora that live in the rumen of ruminant animals like cattle, sheep, and goats. It is formed by the digestion of dietary linoleic acid. The linoleic acid content of grasses varies by plant species and maturity, being highest in grasses that are in a growing, vegetative state. CLA is readily absorbed by the animal from the rumen and ends up in milk, meat, and fat. The concentration of CLA in animal products varies, partly due to diet and management
practices. Even without diet manipulation, lamb is one of the richest natural source of CLA. Dairy products are usually the best sources of CLA. Ewe's milk contains more CLA than cow's milk.
So why feed grain?
Grain-feeding alone or supplementing grain on pasture produces lamb with a milder, more desirable flavor. Grain-fed lamb and beef has generally been preferred in taste panel tests in the U.S., though grass-fed lamb is preferred in the United Kingdom and among some American consumers. Grass-fed lamb tends to have more off flavors and is more subject to oxidation, which affects shelf life and color. Flavor can also be affected by the type of pasture or grain fed. Tenderness is largely a function of age and genetics.
Grazing lambs and kids, as opposed to feeding them grain in a feed lot, offers numerous production advantages. A grass diet is more natural diet than a diet high in grain products; thus, lambs and kids are less likely to suffer digestive upsets or experience other metabolic disorders.
Grass-fed lambs and kids are usually weaned later than their grain-fed counterparts, thereby reducing the risk of mastitis in their dams. Pasture gains are usually more economical than those achieved in the feed lot, though with the high cost of land in many areas, this is becoming a debatable issue. Grass-fed livestock do not usually get as fat as grain-fed livestock.
However, producing lamb and goat from a 100 percent grass diet is not without its challenges. There are more external variables to manage on pasture than in confinement or drylot. Excellent pasture and grazing management is necessary to achieve adequate growth and maintain health of lambs and kids.
Grass-fed animals will generally grow slower than those fed concentrate diets in a feed lot, due primarily to the high moisture content of fresh forage. However, this is not necessarily a bad thing. Lambs will tend to finish at heavier market weights if they are fed lower energy diets for a longer period of time than if they are full-fed high-energy diets for maximum gain.This is especially important for goats and hair sheep lambs, which fatten differently than cattle and wooled breed lambs. If hair sheep lambs and goats are fed for maximum gain (i.e. free choice grain) they will accumulate significant amounts of internal fat around their heart and kidneys. A slower rate of gain is therefore more advisable.
Internal parasites (worms) are a much greater problem with grazing animals than those being fed in confinement or drylot. This is particularly true when grazing small ruminants which may require frequent deworming or handling to monitor parasite levels.
Controlling parasites in grazing livestock, especially sheep and goats, is becoming an even greater challenge due to the widespread emergence of drug-resistant worms. While grazing animals are much less prone to enterotoxemia (overeating disease), urinary calculi, and other metabolic disorders, grazing poses its own set of health risks: poisonous plants, bloat, grass tetany, and fescue toxicosis -- not to mention predators.
As with all production and management systems, there are trade-offs to raising lambs and goats primarily on grass or confining them and feeding them a grain ration. A producer must choose the approprate feeding and management system for his lambs and kids based on his available resources, market demand, and individual preferences. High levels of animal welfare can be achieved in both pasture and confinement/drylot rearing of lambs and kids (and vice versa). There is good market demand for both grain-fed and grass-fed lamb and goat, as well as lambs and kids that consume mixed diets.
References and further reading
[PDF] Factors Affecting Conjugated Linoleic Acid (CLA) Content in Milk, Meat, and Egg: A Review
[PDF] Genetic and Nutritional Effects on Lamb Flavor - Journal of Animal Science
[PDF] Factors Affecting the Palatability of Lamb Meat - University of Wisconsin
[PDF] Biosynthesis of conjugated linoleic acid in ruminants - Journal of Animal Science
[PDF] Conjugated Linoleic Acid (CLA) Implications for Animal Production and Human Health
[PDF] Grass-fed standards for ruminants - University of Arkansas
This article was written in 2005 by Susan Schoenian.