Start Now to Avoid
Summer Breeding Problems
By Mel Dejarnette, Reproductive Specialist
Whether it’s an El Nino year or a La Nina year,
there’s one thing you can count on. Summer usually
means a reduction in conception rates and
reproductive efficiency.
Each year, stress associated with high temperatures
and humidity wreaks havoc on reproductive performance
of dairy herds nationwide. Although there are numerous
"treatments" we can adopt to minimize stress and improve
breeding efficiency of animals during the summer months
(shade, fans, sprinklers, etc.), the best alternative is
to "prevent" animals from needing to be inseminated
during the summer.
However, no matter what we do, all herds will have some
cows that need to be inseminated during the summer. But,
if we can adopt management procedures to get a higher
percentage of the herd pregnant during the spring, there
will be fewer headaches to deal with in the summer. That
means we’d better get busy NOW if we want to avoid hot
stressful weather breeding that for many of you is
less than two months away.
HEAT DETECTION
Spring is a very hectic time on most dairies. Cows
conceiving last spring need to be bred again and crops
need planting. All too often the latter takes precedence.
Don’t let the value of good heat detection slip through
the cracks while the corn planters are in the field. This
may take some rescheduling of labor or possibly adding
some part- time help to cover all the bases.
Since time is usually a critical limiting factor during
the spring, we want to make sure that time spent for heat
detection is used efficiently. Cows are not particularly
interested in displaying mounting activity when they are
distracted by other activities such as feeding or milking.
Schedule heat detection periods to coincide with your
cows’ "leisure" time.
ESTROUS SYNCHRONIZATION
The best way to get more bang from your heat detection
buck is to use some form of estrous synchronization. By
stimulating groups of cows to come into heat at the same
time, you can focus your limited labor more effectively.
At the same time, mounting activity increases several-fold
with multiple cows in heat. A prostaglandin based breeding
program is just what the doctor ordered.
PROSTAGLANDIN BASED BREEDING PROGRAMS
Prostaglandin (PGF) based breeding programs are the
simplest and probably the most cost effective method
of estrous synchronization. Known by many names
(controlled breeding, target breeding and Monday Morning
breeding), the foundation of the PGF based breeding
program is the systematic use of prostaglandins
(Lutalyse or Estrumate) to improve reproductive efficiency
in dairy herds. The key to the success of these programs
is to choose a specific day of the week for injections
that will complement your labor availability for heat
detection/breeding and to inject all eligible cows on
each injection day.
Eligible Cows Include:
- All open cows that are approaching or are just past
the voluntary waiting period (VWP, 45-60 day following
calving in most herds).
- Cows not responding to a previous injection. They
should be reinjected 14 days later. (Animals
not responding by the third injection should be
checked by the veterinarian for cyclicity.)
- Inseminated animals that have been diagnosed
open by palpation.
- Prostaglandin given two weeks prior to the VWP
will increase the percentage of animals in the
proper stage of the cycle to respond at the first
breeding injection and may potentially have
therapeutic benefits that will impact subsequent fertility.
The frequency of injections will vary depending on your
herd size and other management factors. Large herds may
have dozens of eligible cows each week while smaller herds
may only have one or two eligible animals. Therefore,
smaller herds may choose to inject groups of cows at two or
three week intervals.
Having a "synchronized" group of animals in heat coinciding
with returns to estrus of animals that did not settle to
synchronized breedings three weeks previously will greatly
improve the odds of detecting estrus in these repeat animals.
OVSYNCH
The Ovsynch system is a series of hormonal injections designed
to synchronize ovulation in a group of cattle so you can breed
them on a timed basis without observing them for signs of estrus.
The system (shown below) involves an injection of GnRH
(Cystorelin, Factrel or Fertagly) followed seven days later
with an injection of PGF (Lutalyse, etc.) and a second injection
of GnRH 48 hours after the PGF. All animals are inseminated
16-18 hours after the second GnRH injection. Because the second
GnRH injection induces ovulation and shuts down estrogen
production, very few animals will display signs of estrus
after this injection even though they are ovulating and should
be inseminated.
The multiple injections and the need for fairly precise timing
of the injections may make Ovsynch a bit cumbersome to fit into
your daily management routine. However, specific days and times
for injections that appear to fit well in many herds are
suggested in the figure below.
In general, pregnancy rates with Ovsynch over large numbers
of animals have averaged between 30 and 40%. To some, these
numbers may not seem impressive, however, it’s important to
remember that this is the percent pregnant to a single fixed
time A.I. with no heat detection. DHIA data tell me that in
a 21 day period, the "average" dairy producer only catches
50% of the heats in his herd and of those he only gets 50%
pregnant. Thus, the average dairy in the U.S. is only
achieving a 25% pregnancy rate (50% x 50%) during a 21
day period.
The value of Ovsynch will greatly increase as summer approaches.
When temperatures rise, cows are less inclined to exert the
energy necessary to display the physical signs of estrus. This
compounds our heat detection problems. With Ovsynch, the woes
of summer breeding may be greatly reduced.
Although Ovsynch will allow you to breed cows without observing
them for heat, it does not eliminate the need for heat detection.
Some animals may display standing estrus from 24 hours before
to 48 hours after the PGF injection. Optimum conception will
not likely be achieved if these animals are bred strictly on a
timed-A.I. basis. They should be inseminated 8-10 hours after
detected estrus. Additionally, there will always be repeat animals
and natural heats that someone should be watching for every day.
THE HERD BULL WILL NOT CURE YOUR SUMMER BREEDING PROBLEMS
For two reasons;
Summer breeding problems are usually a reflection of reduced
cow fertility. High ambient temperaturesm negatively influence
the uterine environment and its ability to maintain development
of a viable embryo.
Also, since the physiological process necessary to grow and
"ripen" a follicle and egg requires about 60 days from start
to finish, any stress, heat or otherwise, applied to an animal
may influence the quality of eggs and/or C.L.s produced for the
next two months. This partially explains why cows typically don't
fully recover from heat stress until late October to sometime in November.
Bulls get heat stressed, too! The chart above shows that even a
mild heat stress for a short period of time (48 hours) affected
semen quality for as much as a month and a half. Extended periods (weeks) of heat stress may also:
- have negative effects on the quantity of sperm a bull produces.
- extend the amount of time required for recovery of normal levels
of semen production.
- reduce the bull's libido or sex drive.
Although many producers give up and turn the herd bull in during
the summer months, fall pregnancy checks usually indicate that
he did no better and often not as good as you could have done
with A.I.
Like it or not, summer’s just around the bend. Now is the time
to prepare. Use your spring wisely to get as many cows pregnant
as possible before the summer breeding slump arrives.
To order product contact:
Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751
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