Jersey and Guernsey breeds tolerate hot weather better than Holsteins, hence may be the predominant types used for the production of milk in hot weather in certain areas.
Milk is a precursor for many food products. Research efforts have been progressing with increasingly sophisticated approaches that now include genomics and proteomics.
Cow’s milk contains an average of 3.8% fat (called butter fat), 3.3% protein, 4.8% lactose (a 12-carbon sugar), 0.7% ash (minerals), and 87.4% water.
The major proteins of cow’s milk, known as casein, is not one but a group of related proteins. They are bound together with calcium phosphate into particles known as micelles. In one unit, it contains the essential and non-essential amino acids, as well as calcium and phosphorus needed to build bone, muscle and tissue in the newborn.
Milk also contains vitamin and other nutrients in small amounts, making it the most complete of foods.
The genetics and nutrition of dairy cows affect the composition of milk. There are large differences milk fat content among different breeds of dairy cows, ranging from 5.1% for Jersey to 3.7% for Holstein-Friesian cows.
Likewise, Jerseys produce milk with 3.8% protein compared to 3.1% protein for milk from Holstein-Friesian cows.
Cow’s milk in general
