EXPLORING DAIRY ANIMALS ANDDAIRY PRODUCTS

Interest Approach

Ask the students to raise their hands if they like ice cream. Ask them to raise their hands if they like pizza. Now ask them if they know where the ice cream and the cheese on their pizza comes from. Ice cream and cheese are made from milk and milk comes from dairy cows, but how do the cows produce the milk and how is the milk made into other products that we want and that are safe for us to consume? Use this discussion to lead into the lesson.

Student Learning Objectives. Instruction in this lesson should result in students achieving the following objectives:

1 Understand the anatomy of dairy cattle and how they produce milk.

2 Explain how milk is processed for human consumption.

3 Describe dairy products and how they are made.

Terms. The following terms are presented in this lesson (shown in bold italics):

Curds Homogenization Lumens Pasteurized Silage Teat Udder Whey

OBJECTIVE 1: Understand the anatomy of dairy cattle and how they produce milk.

Anticipated Problem: How does a dairy cow make milk?

I. Dairy cows take the food and water they consume and turn it into milk to feed their calves. The milk is also used by humans.

OBJECTIVE 1 continued

A. Dairy cows must be fed properly in order to produce milk.

1. Dairy cows eat a total of 90 pounds of feed a day. 2. They eat about 40 pounds of grain and hay and 50 pounds

of silage a day. Silage is chopped plant material that has been allowed to ferment. Silage may contain leaves, stems, grain heads, and other plant parts. Most silage is made from green, growing crops, such as corn, grass, or sorghum.

3. Cows also drink 25 to 50 gallons of water each day. 4. With this amount of food and water, a dairy cow can

produce about 100 glasses of milk a day.

OBJECTIVE 1 continued

B. Cows make milk in their udder.

1. The udder is a pouch that hangs underneath the cow that contains the mammary glands.

2. The udder is divided into four sections. 3. Each section of the udder has a small tube called

the teat that lets the milk out. 4. Inside the udder are lumens that make small

drops of milk. Once the lumens make enough milk to fill up the udder, milk comes out of the teat when the cow is milked or when she feeds her calf.

5. A cow’s udder can hold 25 to 50 pounds of milk.

STRUCTURE OF A COWS UDDER

F i n e M e m b r a n e

B e t w e e n Q u a r t e r s

O u t e r W a l l o r L a t e r a l

S u s p e n s o r y L i g a m e n t s

A l v e o l i

C e n t r a l W a l l o r M e d i a n

S u s p e n s o r y L i g a m e n t

OBJECTIVE 2: Explain how milk is processed for human consumption.

Anticipated Problem: How is milk processed for human consumption?

II. There are many steps involved in getting milk from a dairy cow into the store.

OBJECTIVE 2 continued

A. Milk must be properly collected from the cow.

1. People have been milking cows for a very long time. For many years farmers milked cows by hand. When milking was done by hand, it took one hour to milk six cows. Today in the United States most of the milking is done by milking machines. With these machines producers can milk 100 cows in one hour.

OBJECTIVE 2 continued

2. Milking machines are placed on each of the cow’s teats and gently suck the milk out of the cow’s udder.

3. The milk is then pumped into a large tank at the farm.

4. A truck from the dairy company comes to the farm, tests the milk, and then takes it to the dairy to be processed.

OBJECTIVE 2 continued

B. Milk must be safe for humans to consume.

1. At the dairy plant, milk is pasteurized, which means it is quickly heated to a high temperature and then quickly cooled.

2. The pasteurization process kills germs and bacteria that are naturally present in the cow’s milk. Germs and bacteria canmake humans sick and can cause the milk to spoil quickly.

3. Homogenization breaks the fat globules in the milk into tiny particles. If this step does not take place, the fat or cream would sit on the top of the milk.

4. After processing, the milk is poured into jugs and cartons to be sold in stores. The milk is never touched by human hands when it is in the plant, so it is one of the safest foods you can eat.

OBJECTIVE 3: Describe dairy products and how they are made.

Anticipated Problem: How is milk changed into other dairy products?

III. Through many processes, milk is made into many different dairy products.

OBJECTIVE 3 continued

A. Ice cream is one of the most popular dairy products. Sugar and flavoring are added to milk and then frozen into ice cream.

OBJECTIVE 3 continued

B. Cheese is made by allowing milk to sour and separate into whey and curds.

1. Curds are the chunks that form in soured milk and are the beginnings of cheese.

2. Whey is the liquid that remains after the curds form. 3. The curds are separated from the whey and aged and

flavored to make the cheeses you eat every day.

OBJECTIVE 3 continued

C. Butter is the cream, or fat, that is present in milk. The fat is removed from the milk and churned or shaken into a solid form called butter.

OBJECTIVE 3 continued

D. Yogurt is made by adding certain bacteria to concentrated, pasteurized milk. The milk is then heated at 110°F for four or five hours to allow the bacteria to grow. The smooth, custard-like texture that is formed is the result of the growth of the bacteria. Flavoring or fruit can be added to the mixture.

REVIEW

1. How does a dairy cow make milk?

2. How is milk processed for human consumption?

3. How is milk changed into other dairy products?