Milk! We all know it's good for us, but scientists at AgResearch are making it even better. They are creating a new type of hyper-immune milk that aims to make our immune system more efficient and us healthier.
Some of the “goodies” in cows’ milk
Milk is a complex mixture of proteins, sugars, fat and vitamins in an aqueous solution. Proteins make up around 3% of this, and there are a variety of different types. AgResearch scientists in the hyper-immune milk research project are particularly interested in looking at the antibody proteins. These form an essential part of the immune system, and are produced by cells called B-cells.
Get information sheet: The immune system
Human babies and calves need antibodies
B-cells produce antibodies in response to specific infections. These antibodies label the invading virus or bacteria for destruction. Some B-cells produce IgG antibodies. In humans, the mother transfers IgG antibodies across the placenta to her fetus.
Cows, on the other hand, are born with no natural immunity to disease. Instead of transferring IgG antibodies via the placenta, the mother cow transfers large quantities of these antibodies to her calf in her colostrum milk. It is vital that a calf ingests these antibody proteins so that it has some ability to cope with all the pathogens in its new environment. After about eight milkings, the colostrum composition changes to that of normal milk with reduced levels of antibodies.
Different types of antibodies
IgG antibodies are the most common antibodies found in a human or cow body. They are mainly in the blood and lymph systems, and in the colostrum of cows. IgA antibodies are common in secretions such as human saliva, tears, perspiration. They are also found in cows’ milk. Both types of antibodies help the immune system by targeting invaders for destruction.
“Hyper” means more than. Hyper-immune milk therefore contains more than the usual level of immuno-proteins. This can be useful in fighting off disease.
Get animation: Hyper-immune - What's the story?
How is hyper-immune milk produced?
Some hyper-immune milk is based on colostrum and the naturally high levels of IgG that are in it.
AgResearch scientists have developed a method to immunise cows with microorganisms that can cause infectious diseases in humans. Using killed bacteria, the immunisation process is similar to that used in all vaccinations of humans and animals.
The immunised cows respond by producing increased levels of specific IgA antibodies in their milk. These antibodies are able to bind to the disease-causing organism. The milk can be collected and processed. These can be used in human food products, and will protect the human gastrointestinal tract from the disease-causing organism.
Delivering hyper-immune milk to the public
The hyper-immune milk that the cows produce will be processed to a powder containing increased levels of IgA antibodies when compared with normal milk powder. The milk powder can then be incorporated into a delivery mechanism, such as a lozenge or a chewing gum.
The advantage of hyper-immune products is that the antibodies in the processed milk powder interact with the pathogen and aid in its removal before the number of pathogens increases dramatically and makes us sick. It would be particularly useful to people whose own immune system is weakened and not able to fight the infectious organisms, for example, people with cancer, or the elderly.
Doing the research
Dr Liz Carpenter leads the hyper-immune milk research project at AgResearch. The animal experiments are closely inspected by an Animal Ethics Committee, which must approve all aspects of the way the work will be carried out.
The immunisation trials on the dairy cows are expensive and time-consuming. The only manipulation of the dairy cows (the immunisation) occurs in the dry period, when the cows are not being milked. However, the animals are observed and milk samples are collected throughout the subsequent milking season.
Over the past ten years, the AgResearch team has immunised hundreds of cows. Careful observations and record-keeping have shown that there is no detrimental effect of the immunisation on the health of the cows.
The majority of the immunisation experiments have been conducted on cows on the Ruakura research farm in Hamilton. However, the immunisation process is very similar to other immunisation dairy cows receive so there are plans to carry out field trials on commercial farms in the future.
Written by Sara Loughnane, NZ Science Mathematics and Technology Teacher Fellow 2006, in conjunction with Liz Carpenter.
- 16 November 2007