Myths and truths about grass finished meat
by Allan Nation
In the early 1990s, New Zealand decided to research the eating quality, flavor and tenderness superiority between grain fed beef and grass fed beef in a two-year scientific study.
Dr. David McCall of Whatawhata Research Centre in Hamilton said some of the widely promoted and generally believed American "facts" about grass fed beef were:
1. Grass fed animals have lower carcass yields and weights.
2. Grass fed animals do not have marbling.
3. Grass fed animals have yellow fat.
4. Grass fed animals are less tender.
5. Grass fed meats have a different flavor and aroma.
6. Grass fed meats have a different color.
7. Grass fed meats are highly seasonal in supply.
In a study of American scientific literature on comparing the two feeding methods, the New Zealanders found that in no American study were animals purposely taken to the same degree of physical maturity before an analysis of the meat was made. They said this violates the basic principles of scientific research. If you are going to compare, you must compare apples to apples not apples to oranges.
The degree of maturity is related to age and weight and the intersection of the two factors. Because grain fed animals gain faster than grass fed animals, they reach mature weights earlier.
If a grass fed steer and a grain fed steer are killed at the same age or when the grain fed animal has become "finished" the grass fed animal will still be growing and will be unfinished. In other words, if we use age it will be an apple to orange comparison.
The New Zealanders found that when cattle of similar genetic background are harvested at similar physical maturities the tenderness and marbling of grass fed and grain fed meat are virtually the same.
Now let's go back through the previous list with animals harvested at the same stage of physical maturity.
1. Carcass Yield and Weight
The New Zealanders said carcass weight is solely a function of growth rate and age. Carcass yield potential at maturity is determined mostly by genetics and secondly by feedstuffs. Animals with superior muscling will have superior lean meat yield regardless of what they are fed.
Big-boned, long-legged, narrow-chested animals have a lower meat-to-bone ratio than thick, full-bodied animals.
In total meat yield, fat cover is also important as fat is counted in total hot weight yield. The amount of fat present is dictated by sex and how heavy an animal is relative to its ultimate mature size.
A rule of thumb Gearld Fry uses is that an English breed, castrated male will typically "finish" at a liveweight that is approximately 100 lbs heavier than its mother. In other words, an 1100 lb Angus cow's son will "finish" at about 1200 lbs in weight.
If you harvest such an animal at 1000 lbs it will not have the same yield percentage because it will not have the same degree of fat as a fully mature animal. The difference can be as dramatic an increase from 50% yield to 60% + yield.
Carcass weight and yield are important because the abattoir cost for the two animals is virtually the same. Therefore, the heavier the animal the lower its harvesting cost.
However, the New Zealanders warned that using European breed genetics can result in an animal whose mature "finish" weight is in excess of today's popular slaughter weights and are unlikely to finish at less than three years of age on pasture.
Intramuscular fat tends to be one of the later fat deposits laid down. High marbling levels became apparent as the animal reaches its mature body size.
Marbling is also influenced by breed and genotype within the breed.
However, the primary determiner of marbling is how close the animal is to its mature size when it is harvested.
In the New Zealand study no difference was found in the degree of marbling between grass fed and grain fed animals harvested at the same weights. An Australian study found the same thing.
The New Zealanders said this is only common biological sense. Animals with the same carcass weight and fatness will have similar degrees of marbling. There is no magic in corn. Meat juiciness is directly related to the degree of marbling. Consumers have been found to mentally correlate juiciness with tenderness but they are not physically correlated in any way that can be objectively measured.
Genetically tender cattle are tender regardless of the degree of (or absence of ) marbling.
3. Fat Color
In many countries, yellow fat is perceived to be from older animals and so is not preferred. However, this yellowness is actually B carotene, which can be metabolized to Vitamin A and is a major anti-oxidant. It could be that with sophisticated consumers, yellow fat will actually be preferred as it is in some continental European countries.
The New Zealand researchers found that yellow fat in grass fed animals was highly seasonal in nature and tended to be the highest in the spring and the lowest in summer. This seasonality was thought to be related to the presence of certain legumes. (Strawberry clover was found to be a prime producer of yellow fat.) In the study, animals harvested in mid-summer had fat color equal in whiteness to grain fed animals.
The New Zealanders found that if an animal is harvested prior to 30 months in age, nutrition has very little to do with meat tenderness. Tender meat is dictated primarily by the animal's genetics and the amount of collagen-connective tissue the animal has.
Through genetic screening, the New Zealanders were able to lower the number of tough meat eating experiences from one in four (the current USA average) to one in seven. While they said this is still way too high, it does show that meat tenderness is primarily a genetics problem and not a nutritional one.
While low meat pH has been correlated with meat tenderness, emotionally stressed animals with high pH meat have also been found to have tender meat but poor aroma and keeping qualities. As an animal ages the texture of the meat changes as the size of the muscle fibers increase, and some consumers may be put off the different mouth feel of this older beef. This was not found to be a problem with animals harvested at less than 36 months of age.
5. Flavor and Aroma
Beef flavor is primarily attributable to compounds (fatty acids) found in beef fat. As an animal increases in age and weight the fat content increases and so does the flavor.
While the diet an animal is grazing can cause changes in the fatty acid composition, these changes are very subtle and may not be detected by most adult consumers.
In the New Zealand study, animals that had been finished on ryegrass to the same degree of fatness as grain fed animals were difficult for most consumers to distinguish between for aroma and flavor.
A taste test at Auburn University found the same thing with ryegrass cattle. However, there consumers objected to the meat taste of cattle finished on fungus-infected fescue.
6. Meat Color
The color of meat is related to the level of pigmentation (myoglobin) present in the muscle.
When beef is cut the myoglobin oxidizes, giving rise to a bright cherry red color and a process known as "blooming."
As animals reach mature weight, the redness increases. High grain rations do indeed produce redder meat than grass fed animals as grain feeding alters the natural level of pigments.
This color shift was found to occur after the animal had been on grain for six weeks.
In the New Zealand study, this slightly less red meat color and the (seasonal) color of the fat were the only two differences found between grain-finished and grass-finished beef harvested at the same mature weights.
The New Zealanders said the greatest variation in the eating quality of all meat lies in the cooking skills of the consumer. Learning to cook all meats at lower temperatures for longer periods would greatly add to their eating quality regardless of the feedstuffs used.
7. Seasonality of Production
Here is where the feedlot system really has a clear advantage, but as the New Zealanders point out, only at a significantly higher cost.
© by The Stockman Grass Farmer
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