Equine Reproduction
Assignment: Read Chapter 18 in the text.
This is the last lesson for this
course. In this chapter you will be exposed to a variety of record keeping techniques
that have been proven to greatly increase the effectiveness of breeding farm
management.
Good records are extremely important
to the smooth running of a horse breeding operation, and can be used very
effectively to alert the management to possible problems. A big part of the effectiveness of good
breeding records is the regular scheduling of record analysis. The following
outline will serve as a study guide and overview of the important aspects of
Chapter 18.
1. Individual
stallion records.
a. Daily
breeding reports – a must for all breeding facilities.
b. Routine
semen evaluations. This is done every other day on many artificial insemination
farms, but may not be done often enough on a live cover operation. It is vital
to be up to date on the semen quality of all your stallions during the breeding
season.
c. Routine
veterinary medications or reports.
d. Notes
on stallion behavior.
2. Stallion
service reservation list.
a. Daily
breeding report.
3. Individual
farm mare records.
a. Daily
teasing, exam and breeding records; a must on all breeding farms.
b. Foaling
records.
c. Suckling
foal records.
d. Routine
vet treatments and medications.
e. Farm
daily logs.
4. Individual
outside mare records.
a. Owner
statements and mare history. This should
be required when a mare is sent to the farm.
b. Breeding
contract.
c. Health
and breeding soundness certificates. (Negative culture and Coggins.) This is
another must for outside mares.
d. Arrival
and departure records.
e. Records
“a” through “e” under farm mare records.
The chapter on breeding records has
some very good examples of different types of forms that can be extremely
helpful in a good record keeping system for a breeding farm.
1. Seasonal
pregnancy rate. The number of pregnant
mares/the number of mares bred times 100. (The number of mares pregnant on a
specific day divided by the number of individual mares bred to that date.)
a. For
the farm, for the year or season.
b. To
a certain date.
c. By
types of mares.
1.
Barren
2.
Foaling
3.
Maiden
Example:
For the year 2004 (breeding
season 2004) let’s say on
July 30 it was determined that
of the 20 individual
mares bred
during that season, 17 were found to be
pregnant.
Seasonal pregnancy rate as of
17/20 =.85 x 100 = 85 per cent.
If these same 20 mares were
checked for pregnancy
again
on November 30 and 15 were found to be pregnant
the
seasonal pregnancy rate for the 2004 breeding
season
would change as of that date to:
Seasonal pregnancy rate as of
15/20=.75 x 100=75 per cent.
The abortion rate from July 30
to November 30 would be
figured
as follows:
2/17=.117X100=11.7
per cent.
2. Cycles /pregnancy is the
total number of cycles / total number
of
pregnant mares. This calculation is a very important
indication
of the fertility or efficiency of the individual stallion.
Example:
If on April 5, it is determined
that a single stallion was
bred
to 25 mares up to that date that have been called
in
foal and of those 25 mares, 20 conceived after only
one
cycle, 3 conceived after having been bred through 2
cycles,
and 2 conceived after having to be bred through
3 cycles, then divide the
number of total
cycles it took
to get
these 25 mares in foal [ (20x1) + (3x2 )+ (2x3) = 32
total
cycles] by the total number of mares in foal (25); or
32/25=1.28 cycles per
pregnancy.
3.
Pregnancy rate per cycle. (Of the total group of mares to be bred
for the season or
to a particular stallion, what percentage of
mares became
pregnant after the first estrous cycle, after the
second and after
the third?)
Example:
At the end of a breeding season
it was determined
that
Stallion One bred 30 mares, of which 10 became
pregnant
on their first cycle, and it took two breeding
cycles
for 10 more to get pregnant. Five mares
became
pregnant
after being bred over 3 cycles , and the final
five
mares required 4 cycles before becoming pregnant.
For Stallion One then:
Pregnancy rate for this group of
mares,
after the first cycle was 10/30=.33x100=33 per
cent.
Pregnancy rate for this group of mares after the
second
cycle was 10/30=.33x100=33 per cent.
Pregnancy rate for this group
of mares after the third
cycle
was 5/30=.165x100=16.5 per cent. And the
pregnancy
rate for this group of mares after the fourth
cycle
was also 16.5 per cent.
Since this group of mares was
bred to only one stallion,
these
figures are valid for evaluating this stallion in
regard
to his fertility if we consider these to be average
mares.
If Stallion Two on the other
hand had been bred to 30
mares
during the same season and it was determined
that
after the first cycle, 20 of these mares had become
pregnant
and after the second cycle 9 mares were found
to be
pregnant, and the one mare was bred 4 more
cycles
and stayed barren through the entire season,
then: Pregnancy rate for this group of mares after
the
first
cycle was 20/30=.67x100=67 per cent.
Pregnancy
rate
for this group of mares after the second cycle was
9/30=.30x100=30 per cent.
So in the case of Stallion Two,
his fertility appears to be
much
superior to Stallion One and therefore could
conceivably
handle a much larger book of mares per
season
that Stallion One.
This parameter is very
individualistic. Some stallions are more fertile than others. Pregnancy rate
per cycle can be helpful in determining this, but you cannot determine a
stallion’s individual threshold at which breeding efficiency declines without
analyzing the records closely. This is important information to be able to
predict the overall fertility of a particular stallion and his breeding
potential. (How many mares to book to this stallion for good
pregnancy rate?)
Mares bred in one week compared to percentage
of mares bred during that week that were pronounced in
foal at 14 to 18 days after that breeding. When this rate begins to decline,
the stallion has begun to reach his threshold of the number of mares that can
be safely bred and expect good pregnancy rates. Any number of mares over that
amount would cause a lowering of that stallion’s sperm output and his pregnancy
rate would go down. This is covered in detail in Chapter 18, but will require a
close analysis of the graphs.
Determining a stallion’s threshold of
efficiency is very important to a Thoroughbred farm where A. I. is not allowed.
Foaling rate percent of mating that
produce a live foal is determined by dividing the number of live foals by the
number of mares bred the previous season. This can be figured for a particular
stallion or an entire operation; it is usually figured both ways. Foaling rate
provides an overall ratio of efficiency, but it does not determine what most
influenced the overall ratio. More specific ratios, such as pregnancy loss
rate, embryo loss rate, fetal loss rate and stillbirth fetal loss rate, can be
used to identify differences at specific times of gestation.
(There
is no quiz for this lesson)
ASSIGNMENT:
Please send to jsales@horsecoursesonline.com "Lesson 10 Repro" in subject
line.
1. Discuss the importance of a good record system
for an equine breeding program.
2. List the major areas for which you would be sure
there were a complete set of records.
3. List the major parameters that would be recorded
on a broodmare’s daily record while at a breeding farm.
4. List the major parameters that would be recorded
for a stallion on the day he is collected for an Artificial Insemination
program.
5. Explain three factors that can alter seasonal
pregnancy rates for a particular stallion.
Determine the answers for questions 6-10 using the
following records for a stallion:
Total number of maiden mares bred in season – 8.
Total number of maiden mares in foal – 6.
Total number of barren mares bred in season – 18.
Total number of barren mares in foal – 12.
Total number foaling mares bred in season – 40.
Total number of foaling mares that got back in foal
– 38.
6. What was the seasonal pregnancy rate for the
maiden group of mares?
7. What was the seasonal pregnancy rate for the
barren group of mares?
8. What was the seasonal pregnancy rate for the
group of foaling mares?
9. What was the overall seasonal pregnancy rate for
the stallion?
10. If the maiden mares that became pregnant were
bred a total of 9 cycles, what was the cycle per pregnancy?