喬·羅賓遜,， 美國著名營養學家， 紐約時報營養膳食類書籍暢銷作者， 在其《完美牧場》 （《Pasture Perfect》）中揭露了青草散養牛奶相較工廠牛奶的眾多營養優勢。
在本書裡， 喬·羅賓遜通過對乳業工廠和青草散養放牧的對比， 發現牛奶中有助於抗擊癌症的CLA（共軛亞油酸）含量和有利於預防各類疾病的EFAs-omega（脂肪酸）比例在這兩種模式下有很大的差距， 通過各類研究， 她全面概述了選擇青草散養乳品的益處以及揭示了散養+草飼對於生產健康乳製品的絕對前提性。 因為事實上， 美國85%-95%的奶牛吃的都不是草， 而是糧食作物等混合飼料；呆的不是青草遍野的牧場，
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首先， 兩種模式下牛奶的CLA（共軛亞油酸）含量差距很大。 所謂CLA（共軛亞油酸）， 其實是一種脂肪， 它在我們的身體裡起到一個最有效的癌症戰士的作用。 青草散養的奶牛產出的牛奶CLA含量高出奶牛工廠的5倍之多。 法國研究人員曾做過360名女性乳☆禁☆房組織的CLA含量水準對比， 結果表明， 乳☆禁☆房組織中CLA含量最高的女性比CLA含量最低的女性少74%患乳腺癌的幾率， 可見CLA含量對於防癌、抗癌有著舉足輕重的作用。
其次， 牛奶中存在的兩種脂肪酸（EFAs-omega-6、EFAs-omega-3）比例不同。 大量研究表明， 如果這兩種脂肪酸在飲食中的比例達到1:1，
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顯而易見， 只有青草散養的奶牛產出的牛奶才能達到兩種脂肪酸間的最佳比例， 而其他不同程度用飼料來取代青草都會造成牛奶中兩種脂肪酸間的不平衡， 導致牛奶營養的缺失。 而在日常生活中， 我們在超市購買的牛奶可能更糟糕， 因為有些奶牛根本吃不到青草， 這也為我們的健康埋下了隱患。
另外， 青草散養的奶牛因為食用新鮮牧草而不是飼料， 因而產出的牛奶中β-胡蘿蔔素、維生素A和維生素E含量比奶牛工廠裡奶牛產出的牛奶要高得多。
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而現代化乳業之所以選擇將奶牛圈禁在工廠裡和用糧食穀物而非青草來餵養它們， 只是因為在這樣的條件下， 奶牛能比青草散養條件下的奶牛產出更多的牛奶。 在牛奶工廠裡， 通常的做法是對奶牛進行每兩週一次的激素注射， 同時， 奶牛一天要擠三次奶， 而不是兩次。 在這樣的產奶機制裡， 奶牛工廠裡的奶牛產量是散養環境下的三倍之多。
如今我們仍然能在澳洲見證喬·羅賓遜筆下的“完美牧場”， 四季常綠的草場為奶牛提供了新鮮的牧草， 廣袤無垠的草地上， 奶牛們肆意奔跑。 放牧原生=草飼+散養， 這種源自澳洲的放牧模式， 在今天已經難能可貴，
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以上資料均選自此文獻:
另附《完美牧場》英文節選
Super Natural Milk
By Jo Robinson
Most cartons of milk in the supermarket show a picture of cows contentedly grazing on grass. In reality, 85 to 95 percent of the cows in the United States are now being raised in confinement, not on pasture. The grass they eat comes in the form of hay, and the ground that they stand on is a blend of dirt and manure.
The reason for confining cows in feedlots and feeding them grain rather than grass is that they produce far more milk under these unnatural conditions. If you also inject them with bi-weekly hormones, standard practice in the dairy industry, they produce even more. Milk them three times a day instead of two and you have the tried and true formula for today’s Super Producers. On average, cows raised in confinement produce more than three times as much milk as the family cow of days gone by and 15 times the amount required to raise a healthy calf.
But with so much emphasis on quantity, the nutritional content of our milk has suffered. One of the biggest losses has been in its CLA content. CLA, or "conjugated linoleic acid," is a type of fat that may prove to be one of our most potent cancer fighters. Milk from a pastured cow has up to five times more CLA than milk from a grain-fed cow. To date, most of the proof of the health benefits of CLA has come from test tube or animal studies. But a few human studies have produced encouraging results. For example, French researchers compared CLA levels in the breast tissues of 360 women. The women with the most CLA in their tissue (and thus the most CLA in their diets) had a 74 percent lower risk of breast cancer than the women with the least CLA [1]. If an American woman were to switch from grain-fed to grass-fed dairy products, she would have CLA levels similar to the women in the study who had the lowest rate of cancer.
Milk from pastured cows also contains an ideal ratio of essential fatty acids or EFAs. There are two families of EFAs—omega-6 and omega-3 fatty acids. Studies suggest that if your diet contains roughly equal amounts of these two fats, you will have a lower risk of cancer, cardiovascular disease, autoimmune disorders, allergies, obesity, diabetes, dementia, and various other mental disorders.[2]
Take a few moments to study the chart below showing EFA levels in milk from cows fed varying amounts of grass and grain.[3] The green bars represent omega-3 fatty acids, and the yellow bars represent omega-6 fatty acids. As you can see, when a cow is raised on pasture (represented by the two bars on the far left), her milk has an ideal, one-to-one ratio of EFAs.
Take away one-third of the grass and replace it with grain or other supplements (represented by the two bars in the middle) and the omega-3 content of the milk goes down while the omega-6 content goes up, upsetting an essential balance.
Replace two-thirds of the pasture with a grain-based diet (illustrated by the two bars on the far right) and the milk has a very top-heavy ratio of omega-6 to omega-3 fatty acids. This ratio has been linked with an increased risk of a wide variety of conditions, including obesity, diabetes, depression, and cancer. Much of the milk you buy in the supermarket has an even more lopsided ratio than this because the cows never graze on pasture.
Milk from pastured cows offers additional health benefits. (I'm beginning to sound like a TV infomercial: "But wait! There's more!") Besides giving you five times more CLA and an ideal balance of EFAs, grass-fed milk is higher in beta-carotene, vitamin A, and vitamin E. This vitamin bonus comes, in part, from the fact that fresh pasture has more of these nutrients than grain or hay. (When grass is dried and turned into hay, it loses a significant amount of its vitamin content.) These extra helpings of vitamins are then transferred to the cow's milk.
There's another factor as well. As I mentioned, a cow raised on pasture produces far less milk than a cow raised in a confinement dairy on a grain-based diet. This is a bane for the farmer but a blessing for the consumer. The less milk a cow produces, the more vitamins in her milk.[4] This is because a cow has a set amount of vitamins to transfer to her milk, and if she's bred, fed, and injected to be a Super Producer, her milk has fewer vitamins per glass. It's a watered down version of the real thing.
Oh, I almost forgot the best part of all. Dairy products from grass-fed cows taste delicious, and they have a rich yellow color that is visible proof of their bonus supply of carotenes. Serve cheese or butter from a grass-based dairy, and everyone will notice the difference. Also, your cookies and cakes will have that rich buttery color that hasn't been seen since Great-Grandma's day. (You do bake, don't you?)
So where can you find milk from pastured cows? All of the dairies listed onwww.eatwild.com keep their cows outdoors on grass whenever possible. Some farmers supplement their cows with small amounts of grain; if so, their listing will detail the type and amount. To find your local producer, go to our list of grass-fed suppliers and click on your state. We also have a special section devoted to farmers who feed their cows 100 percent forage-based diets.
Expect to pay more for this high-quality milk from humanely treated cows. The main reason is the low volume of milk per cow. In order to make a living, pasture-based dairy farmers must get a premium price for their premium milk.
Got grass-fed milk?
Jo Robinson is a New York Times bestselling writer. She is the author or coauthor of 11 nationally published books including Pasture Perfect, a comprehensive overview of the benefits of choosing products from pasture-raised animals, and The Omega Diet (with Dr. Artemis Simopoulos) the healthiest diet of all Mediterranean diets . To order Jo’s books or learn more about grass-fed products, visit http://eatwild.com.
[1]Bougnoux ,et al.,Inform, 10:S43, 1999.
[2] For more information about essential fatty acid balance, read The Omega Diet. The book provides 24 pages of pertinent scientific references.
[3] The data comes from: Dhiman, T. R., G. R. Anand, et al. (1999). "Conjugated linoleic acid content of milk from cows fed different diets." J Dairy Sci 82(10): 2146-56.
[4] Jensen, S. K., A. K. Johannsen, et al. (1999). "Quantitative secretion and maximal secretion capacity of retinol, beta-carotene and alpha-tocopherol into cows' milk." J Dairy Res 66(4): 511-22.
