Effective A.I. Management Can Be Important Tool To Improve Reproductive Efficiency Among Dairy Herds
PLAIN CITY, Ohio, Dec. 9, 2003 — Dairy producers aiming to improve fertility
among their herds should pay close attention to management and
semen-handling procedures when artificially inseminating cows, says Mel
DeJarnette, reproductive specialist with Select Sires.
DeJarnette recently completed an extensive review of research tracking semen
quality and fertility among A.I. sires. Although dairy producers are facing
greater challenges getting cows bred, he says, "There’s nothing to indicate
we’ve changed fertility of the dairy male."Findings of the review, which
were presented in June at the national meeting of the American Dairy Science
Association, compared scrotal circumference, motility characteristics, acrosome
integrity and sperm morphology of today’s dairy A.I. sires to those of dairy
sires that were used more than 30 years ago.
DeJarnette reports that no significant differences were found between semen
quality or fertility indicators of the sires themselves. However, with the
implementation of new technologies for semen processing, health testing and
disease control, and a greater understanding of the relationship between
semen quality and fertility, he says, "The quality and fertility of today’s
commercially available semen is as good or better than it has ever been.
From this data, it does not appear that the A.I. sire is playing a
significant role in the declining reproductive efficiency among dairy
herds."
He adds, "There are quality-assurance measures in place to ensure that the
semen available from major A.I. organizations will get your cows bred." But,
DeJarnette adds, "Field fertility trials continually show that there is
tremendous variation in fertility from herd to herd, even when using the
same ejaculate from the same bull, whereas within a herd, variations in the
fertility among sires are much less significant." This suggests environment
and management of cows as having greater impacts on reproductive performance
than does sire fertility, he says.
Management Solutions
To address fertility concerns, DeJarnette says nutritional management of
transition and fresh cows is especially critical. "Certainly it takes good
management to get high production. However, at the same time, today’s
high-producing dairy cow may be more sensitive to management deficiencies
than the dairy cow of yester-year."
Additionally, DeJarnette emphasizes that A.I. conception requires adhering
carefully to the industry’s recommended semen handling procedures. "The
waters have been muddied over the years as to the appropriate A.I.
procedures, but in essence, the practices that were recommended twenty years
ago, are still applicable today," he explains. Those procedures include:
- Keep unused straws below the frost line in the neck tube of the tank.
DeJarnette calls this the "most damaging of all semen-handling errors," and
reports that the viability of cryopreserved semen that is re-cooled to
liquid nitrogen temperatures after rising to as low as -70 C is totally
obliterated.
- Thaw straws in 35 C water (range 33 C to 37 C) for a minimum of 45
seconds. While this is the standard rule, DeJarnette recommends inseminators
always follow the specific manufacturers’ thawing recommendations.
- Thaw no more straws than can be deposited in the cow within a 10- to
15-minute period and maintain straw temperature and hygiene throughout the
A.I. process. Research suggests thawing multiple straws does not compromise
conception rates, however, failure to control semen temperature, hygiene or
recommended time constraints likely will compromise conception rates
irrespective of the number of straws thawed, says DeJarnette.
- Consider site of semen deposition. Most A.I. organizations recommend the
uterine body as the proper site for semen deposition. Results of research
comparing uterine horn and uterine body deposition are not consistent, says
DeJarnette, however, the primary concern is to ensure that semen deposition
occurs anterior to the internal cervical os.
- Inseminate only cows that are actually in estrus at timings that are
consistent with the "a.m./p.m. rule." DeJarnette suggests a major reason
that reproductive efficiency appears to be declining is that greater numbers
of cows likely are being inseminated actually are not in estrus. This is a
side effect of estrous detection programs that are based more on tail-chalk
and other secondary signs of estrus compared to the good old standing heats
in dirt lots of yester-year, he says, and adds that this is especially
concerning with respect to previously inseminated cows, where non-estrus
inseminations have been shown to be 60 percent to 90 percent efficacious for
inducing an abortion. DeJarnette offers several guidelines: a) For
previously inseminated cows, use a conservative approach in diagnosing signs
of estrus, b) cows detected in estrus should be inseminated at the next
convenient opportunity and no later than 10 to 12 hours after detected
estrus, and c) when appropriate insemination timing is in question, early
insemination is less likely to compromise conception than late.
Lastly, DeJarnette reminds producers that they need to focus on what can be
done "in the here and now" to address fertility. He cautions that the
recently available daughter pregnancy rate data should only be considered a
secondary tool. "It is a new tool, but the amount of progress it will afford
is small and will not be realized for three to four years. Who with breeding
problems can afford to wait that long? Instead, producers need to start with
environmental management and maintaining a healthy herd to work toward
improved fertility."
Based in Plain City, Ohio, Select Sires Inc. is a federation of 10
farmer-owned and -controlled cooperatives. It provides highly fertile semen
as well as excellence in service and programs to achieve its basic objective
of supplying livestock breeders with America’s best genetics at a reasonable
price.
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