Doc’s Blog

Epigenetics: Tracing the health
 of embryos through the generations

     Many livestock experts are prone to pontificate on the importance of  the first 60 days of a calf’s life.  They claim a calf’s highest genomic potential is the day it is born  and it has 60 days to reach its full genetic potential.  They are right, of course, but it is also helpful to take a look backward in time and examine previous generational factors influencing a calf’s health at birth.   

     Epigenetics is the study of changes produced in genetic expression without changes in the underlying genes or DNA sequence.  The genes are like switches that can be turned on or off by diet, toxins, stress, behavior, and other factors. These changes — both good and bad —  can be inherited by future generations.  If you think of a computer as a collection of genes (hardware), then epigenetics would be the computer program (software) that runs the computer.

     In light of the above, the health of a calf at birth is the end result of a series of events beginning at least a generation ago —and possibly as far  back as three or four generation. 

     Simply put,  this newborn calf was a dormant ovum in its mother’s immature ovary when its mother was an unborn calf in its mothers uterus, who was, in turn, a calf in its dam’s uterus, and so on back through several generations.  (See chart)   Anything you do or don’t do for the mother cow will affect future generations of her offspring.  

     One real-life example of epigenetics is the better health and production seen in dairy cattle a generation or two after switching to organic. Nutritious, toxin free organic crops affects genetic expression in a positive way.

     Applied to humans, “. . . if you are of reproductive age, what you eat, drink, breathe or experience can affect the health of your great-grandchildren in the same ay that  as you may be experiencing the effects — good or bad — of your great-grandparents experiences and environment.”

     You can’t change the past but you can use epigenetic principles to manage the diet and environment of your animals  to insure optimum genetic expression. 

     Providing adequate, balanced minerals to all breeding animals, at all times, is the keystone to good nutrition and to the preservation and improvement of genetic expression for future generations. 

525,000 Dead Calves

     On March 23, 2015 I posted a blog entry entitled “Inbreeding” in which I pointed out 49% of today’s Holstein genetic lineage go back to a famous bull known as Chief (Pawnee Farm Arlinda Chief).  I commented one of the pitfalls of inbreeding was  diminished reproductive efficiency.

     Now, a recent article in Progressive Dairyman reports genomic research has found a genetic defect in Chief and some of his sons.  This defect has been linked to decreased conception rates and increased stillbirths. It is estimated to be the cause of 525,000 stillborn calf deaths worldwide.  One of the researchers opined the reason it took so many decades to find the problem was because most abortions are blamed on the cow rather than the bull. 

     The PD article states Chief is responsible for 14 percent of the current Holstein genome in the U.S.  The difference between this figure and the 49% quoted above is due to differences in the time period and the degree of relationship sampled.

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     Chief’s offspring include more than 16,000 daughters, 500,000 granddaughters, and 2 million great-granddaughters, as well as several sons that became popular sires. Mark, one of Chief’s sons is pictured above.

     This discovery confirms my belief in a more restrained approach to meddling with genetics.  Chief’s problem arose from the relatively benign selective breeding techniques practiced for centuries.  I fear the current craze to indiscriminately mix genetics from different species will someday come back to bite us in the butt. 

     Hopefully, one day soon, we will collectively experience a moment of lucidity, slap ourselves on the forehead and say; “Maybe we ought to be more careful fooling around with Mother Nature”. . . .  but I’m not holding my breath while waiting for it to happen. 

Learn more about Chief at:  http://www.progressivedairy.com/topics/a-i-breeding/genetic-mutation-from-one-bull-caused-loss-of-500-000-calves

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