SELECTIONS - Summer 2002
Although Difficult, Producers Can Improve Fertility in Summer's Heat
While decreased production is a concern during the heat of
the summer, decreased reproductive performance is another
outcome that can cause long-term economic losses for dairy
producers. In addition to adopting management techniques that
help reduce heat stress, producers can improve reproductive
efficiency by implementing strategic estrus-synchronization
programs, using artificial insemination and breeding cows
with highly fertile semen.
"At this time of year, providing cows with convenient access to
shade and ample supplies of cold water, and avoiding overcrowding
are important keys to managing heat stress," says Mel DeJarnette,
reproductive specialist. "Despite the best heat-management techniques,
however, keeping fertility high during the summer is still a challenge.
Although it can be tempting to use a herd bull, top producers continue
to use A.I. year-round, recognizing that heat stress affects the
fertility of bulls too."
Researchers at Virginia Tech, Blacksburg, Va., conducted research to
better understand the effects of heat stress on semen production. One
study found that after the initial heat stress, it took as much as 1½
months for production to return to normal.
"The bottom line is that you can’t depend on a herd bull to get cows
bred during the summer," says DeJarnette. "That’s why more producers
turn to highly fertile frozen semen that has met stringent quality-control
standards, including semen from sires that have been designated as
SUPERIOR SETTLERs™." (A complete listing is shown at the end of this article.)
What you can do to control heat stress
Heat-stressed cows are reluctant to mount since physical activity
increases body temperature. So while cows typically cycle normally,
it is harder to catch them in heat. And, in the south-eastern United States,
cows tend to have shorter and less-intense heats than cows in cooler
environments.
Heat-stressed cows, however, do respond extremely well to prostaglandin
injections. That’s why estrus-synchronization programs can be implemented
effectively along with programs that manage heat stress.
In addition, time-tested mechanical aids, such as fans and misters,
continue to be cost-effective options in the battle against heat. Since
cows often reduce their feed intake by as much as 25 percent during heat
stress, increasing the protein and energy content of feed while reducing
fiber intake can help.
When it comes to managing reproduction, using estrus synchronization and
A.I. are important tools.
Producers should work with a veterinarian or reproductive specialist to
develop a program to help get cows bred this summer, then adopt a
synchronization program next spring to reduce the number of cows that
will have to be bred during the summer of 2003.
SUPERIOR SETTLERs
While there are many variables that affect pregnancy rates, looking at
fertility values of sires can help improve these rates. What follows is
a list of sires with the SUPERIOR SETTLER designation - the mark of higher
fertility given only to sires that excel in laboratory analysis and field-based
non-return data.
Milk Rel Type Rel
*7HO3707 MATHIE*CV +1,214 99%M +1.04 99%M
*7HO4364 ROAD MARK*TV + 439 99%M +1.69 98%M
*7HO4525 RUBYTOM*TV +1,871 99%M +0.76 99%M
7HO5157 DURHAM*CV + 601 99% +3.09 96%
*7HO5192 WAHOO*TV +1,775 90% +0.49 82%
*7HO5206 CLARK*TV + 878 90% +1.53 84%
*7HO5211 BLACKBART*TV + 744 97% +2.09 92%
*7HO5300 MAGNUM*CV +1,632 96% +0.91 90%
*7HO5439 CONGO*TV +1,761 89% +0.82 83%
*7HO5484 BOONE*TV +1,512 91% +1.07 87%
*7HO5605 WARRIOR*TV +1,507 86% +1.25 82%
*7HO5631 NEYER*TV +1,760 88% +1.20 83%
*7HO5650 ALLOY*TV +1,991 88% +0.96 86%
*7HO5653 BRASS*TV +1,392 85% +2.49 83%
*7HO5708 BLITZ*TV +2,363 88% +2.36 85%
*7HO5760 LINK*TV +1,672 86% +1.77 83%
*7HO5785 ADAM-RED*TV + 385 94%M +1.16 87%M
*7HO5788 GENT*TV +1,776 81% +1.42 79%
*7HO5799 SAHARA*TV + 892 82% +1.05 82%
*7HO5801 TRUE GRIT*TV +1,102 86% +2.06 83%
*7HO5804 RICKY*TV +1,289 81% +1.08 78%
*7HO5886 MONROE*TV +1,333 83% +0.41 76%
*7HO5891 DILLON*TV +2,033 88% +1.62 86%
*7HO5975 HARMON*TV +1,397 82% +2.23 81%
*7HO5996 CLEM*TV +1,441 81% +1.95 76%
*7HO6014 DEADEYE*TV + 575 81% +1.84 77%
*7HO6104 ACHIEVER-RED*TV +1,502 76% +1.42 62%
7HO6247 ELATION*TV +1,746 87% +2.05 79%
*7HO8419 APPROVAL*TV + 591 87% +2.68 82%
*9HO2344 COOPER*TV +1,044 88% +1.50 83%
*9HO2393 SHAWNEE*CV + 950 87% +1.31 85%
*9HO2394 CRACKER*TV + 726 89% +1.41 86%
*9HO2448 SPOCK*TV + 481 89%M +1.90 85%
*9HO2462 NIXON*TV +1,572 87% +1.57 85%
*9HO2517 JETTA*TV +1,684 86% +1.95 80%
*9HO2608 BENEDICT*TV +1,032 98% +0.39 89%
*7JE290 BARBER + 866 99%M +1.50 99%M
*7JE424 FREEDOM +1,476 88% +1.90 79%
*7JE472 PARADE + 937 90% +2.60 83%
*7JE488 BARKLY +1,805 82% +1.60 69%
*Qualified for semen export to Canada.
05/02 USDA, HA & AJCA PTAs. M=IB-M/USA.
™SUPERIOR SETTLER is a trademark of Select Sires Inc.
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