Transgenic cows fight mastitis

Animal science professor Dr. David Kerr is currently researching a new way for farmers to fight mastitis, an infection of a cow’s udder that is associated with the staphylococcus aureus bacterium. Essentially, mastitis increases the somatic cell count within the milk of the affected udder quarter. This increase can make that quarter’s milk lumpy or watery, both conditions that force farmers to abandon the milk and lose money. Also, treating a cow for mastitis is a costly venture, not only because of the price of the medicines, but also because of the amount of milk lost while the cow is being treatedMastitis is a huge problem in the dairy industry, costing farmers an average of two million dollars per year, or about 200 dollars a year per cow. If farmers were able to save that money, then the cost of milk could ultimately be reduced, and farmers’ earnings could be increased. Dr. Kerr is working with the U.S. Department of Agriculture, researching a solution to this problem involving transgenic cows. A transgenic organism is one that has been manipulated to contain both its own genes and one or more genes from another organism. When scientists are successful, the transgenic organism expresses a different phenotype, or appearance, than before the manipulation. Some scientists have tried to insert a gene from jellyfish, responsible for their luminescence, into a monkey, and achieved the expected result: a glow-in-the-dark monkey!In 2001, Dr. Kerr’s first accomplishment was born: Anne, a cloned cow. Kerr found a way to encode the amino acids that make up lysostaphin, an antimicrobial protein that can kill s. aureus, into Anne’s DNA. This cow was then able to produce lysostaphin in her milk, and ultimately resist infections by s. aureus. Dr. Kerr has tested the produced milk to make sure that it is safe for human consumption, and so far milk with lysostaphin has been shown to be completely harmless to humans. Milk with lysostaphin also does not affect culturing milk for yogurt or cheese. Currently, Dr. Kerr is attempting to find the best way to introduce this new teachnology to the agricultural market. He has created a bull which has the amino acid sequence for lysostaphin within its DNA, which serves as a possible father for future calves with the resistant genome. The bull has a 50% chance of passing the resistant genome on to his children. He hopes to introduce this bull’s sperm into the traditional breeding schemes of artificial insemination. Dr. Kerr feels that with further breeding, they will be able to create a homozygote, which he will then be able to use to create resistant cows 100 percent of the time. Right now, Dr. Kerr is working with graduate students to create ways for cows to become resistant to other causes of mastitis, such as E. coli and various strains of streptococcus, and he feels the technology is endless. The success of Dr. Kerr’s research is inspiring to all scientists, and though transgenic work is limited to animals, his research may spill over to the field of gene therapy research, which is a similar procedure for humans. Keep an eye out for advancements in the field of creating transgenic organisms, and start watching those milk prices!