The Milk Producer - February 2010 - (Page 34)

RESEARCH By Vanessa Perkins Johne’s targeted Identifying genes that contribute to disease resistance may lead to improved treatment University of Guelph researcher is using molecular techniques to identify what genes make some cattle resistant and others susceptible to Johne’s disease. Department of animal and poultry science researcher Dr. Niel Karrow believes identifying the genes that contribute to disease susceptibility or resistance may lead to improved drugs and screening tests to detect early-infected calves. These genes could be used as genetic markers to identify disease-resistant cows for selective breeding. However, Karrow raises a note of caution about breeding for resistance to Johne’s; it could increase a cow’s disease susceptibility. Johne’s disease is a chronic, inflammatory bowel disease that can reduce milk production. It is caused by Mycobacterium avium paratuberculosis (MAP) and shed through an infected cow’s milk and manure. It can damage the digestive tract reducing nutrient absorption, causing chronic diarrhea and loss of body condition, despite normal appetite. It may also result in death. MAP is a particularly hardy organism, able to survive in soil or water for more than a year. It may go undetected in cattle until after the fourth lactation. A cow could infect a significant percentage of the herd before displaying symptoms. The disease, which is difficult to detect and may be resistant to antibiotics, appears to be on the rise in Ontario herds. Karrow and his research team are among a handful of researchers worldwide studying Johne’s disease. Graduate student Sameer Pant is using an approach called the Whole Genome Analysis to identify the genes that cause Johne’s. The analysis uses about 50,000 genetic markers to pinpoint the genes associated with resistance or susceptibility. Research associate Dr. Bhawani Shankar Sharma is using a kind of genetic analysis to identify cows that could be targeted for potential drug development. “This research could head in so many directions,” says graduate student Chris Verschoor, also involved in Johne’s research. “How the bacteria affect cattle species differently, where the bacteria actually go once introduced in the animal, and how the immune system responds to MAP infection are all really promising areas of future research in Johne’s disease.” Using genetic markers to develop improved screening tests to detect early-infected calves for Johne’s disease could lead to better drugs. 34 | February 2010 | MilkPRODUCER Vanessa Perkins is a student writer with the University of Guelph’s office of research. Dr. Stephen Moore from the University of Alberta is collaborating on this research project. Funding for this research was provided by the Natural Sciences and Engineering Research Council, Dairy Farmers of Ontario and DairyGen Canada.

Table of Contents for the Digital Edition of The Milk Producer - February 2010

The Milk Producer - February 2010
Contents
Editor's Notes
DFO Chair's Message
Dairy Update
DFC Policy
Industry Roundup
DFC Promotion
Quest for Quota
Issues Update
Research
Applied Science
Ruminations
Markets
New 'N' Noted
Back Forty

The Milk Producer - February 2010