奶牛的喂食方式可以对牛肉的营养成分产生重大影响。

Whereas cattle today are often fed grains, the animals people ate throughout evolution roamed free and ate grass.

许多研究表明，牛肉中的营养因素可能会根据奶牛的饮食而有所不同。

牛肉是大量生产的地方，例如在美国，通常会喂牛。但是，草食牛肉在许多其他国家（例如澳大利亚）很常见。

你可能想知道是否喂牛的方式any difference to your health.

This article looks at the evidence to determine the differences between grass- and grain-fed beef.

In the United States, most cows start living similar lives.

The calves are born in the early spring, drink milk from their mothers, and are then allowed to roam free and eat grass or other edible plants they find in their environment.

This continues for about 7–9 months. After that, most conventionally raised cows are moved to feedlots.

Large feedlots are called concentrated animal feeding operations (CAFOs). There, the cows are kept in confined stalls, often with limited space.

They are rapidly fattened with grain-based feeds that are usually made from a base of soy or corn. Typically, their diet is also supplemented with small amounts of dried grass.

The cows live in these feedlots for a few months before being brought to a slaughterhouse.

Of course, it’s not that simple. The different feeding practices are complicated and varied.

例如，澳大利亚的草食牛肉可能无法与美国产品直接相提并论，而草食牛肉不一定会饲养牧场。并非所有的草食奶牛都可以在户外吃草。

实际上，草喂的一词并未明确定义。

That said, grass-fed cows eat (mostly) grass, while grain-fed cows eat (mostly) an unnatural diet based on corn and soy during the latter part of their lives.

To maximize growth, the cows are often given drugs, such asantibioticsand growth hormones.

截至2017年1月1日，食品和药物管理局（FDA）通过了新的立法，称为兽医饲料指令。

According to this legislation, antibiotics that are considered important in human medicine need to be administered under the oversight of a licensed veterinarian and cannot be used for growth promotion ( 1 ).

Summary

Most cows start on a pasture, drinking milk and eating grass. However, conventionally raised cows are later moved to feedlots and fed mainly grain-based feeds.

“You are what you eat” applies to cows, too.

What a cow eats can significantly affect the nutrient composition of its beef. This is particularly evident when it comes to fatty acid composition.

草食牛肉通常含有比谷物喂养的牛肉少的脂肪，这意味着克拉姆，草饲牛肉含有更少的卡路里（ 2 ).

However, the composition of fatty acids is also different:

  • Monounsaturated fat.Grass-fed beef contains much less单不饱和脂肪比谷物喂牛肉（ 2 ).
  • Omega-6 polyunsaturated fats.Grass- and grain-fed beef contain very similar amounts of omega-6 fatty acids.
  • omega-3s。This is where grass-fed makes a major difference, containing up to five times as muchomega-3（（ 3 ).
  • 共轭亚油酸（CLA）。Grass-fed beef contains about twice as muchCLAas grain-fed beef. This fatty acid is associated with a few health benefits ( 4 ，，，， 5 ).

简而言之，草和谷物喂养的牛肉的脂肪成分和量存在显着差异。

此外，肉类的品种和肉类极大地影响了牛肉的脂肪成分（ 2 ).

Summary

Grass-fed beef may contain less total fat than grain-fed beef, but a lot more omega-3 fatty acids and CLA, which are both linked to health benefits.

Both grain- and grass-fed beef are highly concentrated sources of nutrients.

Beef is loaded with vitamin B12, B3, and B6. It’s also rich in highly bioavailable iron, selenium, and zinc. In fact, meat contains almost every nutrient that you need to survive ( 6 ).

它还包含高质量的蛋白质和各种鲜为人知的营养素，例如肌酸和肌肽，这对您的肌肉和大脑非常重要。

但是，即使差异不是很大，草食牛肉通常含有更高量的某些营养素。

与谷物喂养的牛肉相比，在以下维生素中草喂养要高得多：

  • 维生素A。Grass-fed beef contains carotenoid precursors to vitamin A, such as beta carotene.
  • 维生素E.This antioxidant sits in your cell membranes and protects them from oxidation ( 4 ).

Grass-fed beef also tends to be richer in other antioxidants ( 7 ，，，， 8 ).

Summary

常规的谷物喂养牛肉是高度营养丰富的，但是草食牛肉含有更多的类胡萝卜素，维生素E和其他抗氧化剂。

It’s important to keep in mind that even conventional, grain-fed beef is very nutritious.

只要你不要煮牛肉，这可能导致有害化合物的形成，这是一种营养食品，可以成为健康饮食的一部分。

在美国，草食牛肉可能更昂贵，对于某些人来说，这可能不值得额外的费用。

Depending on where you live, it may also be inconvenient to buy grass-fed beef.

While some people may live close to a farmer’s market or whole foods store, others may need to drive long distances to find grass-fed beef.

口味也可能存在细微的差异。草食牛肉通常更苗条，可能具有不同的质地。

即使草食牛肉含有更高量的某些营养素，目前尚无令人信服的证据表明，在均衡饮食的背景下，它比谷物喂养的牛肉更健康。

最后，选择取决于您的偏好和理想。有些人喜欢草喂，而另一些人则喜欢谷物喂养。尝试两者，看看您更喜欢哪个。

Summary

Although grass and grain-fed beef differ in several nutrients, their effects on your health may be similar.

Despite all the controversies in the field of nutrition, most people agree that the most important thing is to吃真正的食物。

Some people like to take this idea a step further and only eat real food that eats real food. After all, grasses and herbs are a more natural diet for cows than corn and soy.

归根结底，选择取决于您的偏好和价值观。