Brenda Lee-Turner, Semex Alliance Marketing Communications Specialist With temperatures topping +90Ë�F/32Ë�C in many parts of the North America, dairymen are struggling to get their cows bred back on time.  Heat and its partner in crime, humidity, wreak havoc on dairies, pushing milk production and pregnancy rates down and herd health problems up.  Incidences of stress on cows can occur at temperatures as low as 72Ë�F/22Ë�C when combined with higher humidity, dramatically reducing profitability on the dairy.    Looking for solutions to keep the window of breeding opportunity open a little longer and combat these issues, Semex has designed its Repromixâ"� product to help get those problem, repeat breeders back into calf, reducing days open and into their next lactation and the milking line. The theory behind Semex’s Repromix product is related to a phenomenon called capacitation.  Capacitation is a series of changes all sperm from mammals must undergo while in the female reproductive tract in order to fertilize an egg.  This process includes the modification of proteins on the outside of the sperm cell by the cow’s reproductive tract.  Without this process, sperm cannot fertilize an egg.  As timing with all reproduction is key, the time needed for the capacitation process to occur varies from species to species and in our case, bull to bull.  “Based on our theory, bulls can have different capacitation profiles,â€� says Tom Kroetsch, Semex Alliance Director Production & Quality Control.  “But (all sires) will still have very good fertility when used in normal fertility cows in most herds with good reproductive management.â€�  In general the timeline for capacitation in bull semen is generally 4 to 12 hours, but as shown in Figure 1 there appear to be early, average and late capacitating bulls.  “Semex’s Repromix combines the semen from three bulls with complementary capacitation profiles,â€� says Kroetsch.  “This makes more healthy sperm available and ready to fertilize an egg, in a hard to settle cow, over a wider window of opportunity than what just one bull can manageâ€�. 12-14 hours versus just 4-8 hours.â€�  Each one of the three sires in a straw of Repromix is proven to have high fertility and high overall semen quality, along with the standard Balanced Breeding that backs all Semex sires.  With each bull having a unique capacitation profile, Repromix offers more freshly capacitated sperm to meet the egg over a longer period of time, helping to settle the repeat breeder.   See Figure 2.     As temperatures rise in many parts of the world, Semex’s Repromix product will help keep pregnancy rates from dropping and profitability up!  Contact your local Semex Representative for Repromix today or click here for more information.