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COLLECTION: GOAT HANDBOOK
ORIGIN: United States
DATE INCLUDED: June 1992
Extension Goat Handbook
This material was contributed from
collections at the National Agricultural Library.
However, users should direct all inquires about the
contents to authors or originating agencies.
DOCN 000000032
NO D-6
REPRODUCTIVE MANAGEMENT
E. L. Bliss; U. of Florida, Gainesville E. A. Oltenacu;
Cornell U., Ithaca, NY R. S. Ott; U. of Illinois,
Urbana S. B. Guss; Pennsylvania State U., University
Park
Genetics and Reproduction
1 The reproductive performance of goats can be exceptionally
high. Conception rates of 980ver 2 estrous cycles
with an average of 1.5 kids have been reported. Such
fertility is probably due to maximizing proper management.
Reproductive management of dairy goats involves three
periods: the breeding season, the pregnant and dry
period; and kidding time.
2 The Breeding Season Yearling kids
may be bred in the first year at 7-10 months of age,
depending on breed, if they have grown well to about
80 lb and are of good size and condition. Body weight
relative to breed is more important than age and can
influence lifetime performance. The doe kid may be
able to reproduce at three months of age but should
not be allowed to do so, as her growth may be permanently
stunted. To prevent this, buck kids should be separated
from doe kids at an early age. If breeding doe kids
is postponed much beyond 10 months of age, they will
be less productive. Older kids are not as easily settled
at first breeding and may have lower lifetime productivity.
3 Breeding does, as the season approaches
should be ''flushed'', i.e. prepared by having them
gain weight at least 2-3 weeks before breeding. This
increases the number of ovulations. Records should
be kept carefully on all heats, lengths of heat, intervals
between heats and all breeding dates. Most goats are
seasonal breeders, and their season is initiated by
decreasing daylight. Thus, their season is from late
August through January usually, but tropical breeds
of goats may cycle year around.
4 Seasonal breeding results in seasonal
peaks and valleys of milk production which makes it
difficult to maintain a level fluid milk market. However,
goats can be milked longer than the standard 305-day
lactation by delaying breeding to a later heat. Goats
can also be ''fooled'' into thinking that the short-day
season has arrived by manipulating artificial light-hours
per day and thereby initiating estrous cycles out-of-season.
However, this requires an investment in housing which
is suitable for light control.
5 Hormonal reproductive problems
are not common in goats. Cystic ovaries may occur,
usually late in the breeding season. These are a hereditary
problem and show up in young animals. The signs of
cystic ovaries are constant heat, male-like behavior,
or frequent short cycles. Treatment may consist of
giving hormones: luteinizing hormone containing compounds
(3,000 IU/im) or progesterone in oil (100mg/d for
12 days). Young does with cystic ovaries probably
should not be bred and be culled, to prevent the continuation
of this condition.
6 Anestrus (no heats) can be a problem.
This may be due to: a pregnancy from an unobserved
service, if a buck is present; intersexed goats which
are not discovered until examined to determine why
they are not cycling; the inability to observe does
in heat; or simply not cycling. Close observation
and understanding the signs of estrus is the best
way to determine when the doe is in heat. Signs of
heat (estrus) are: swelling and redness of the vulva:
mucus discharge (may become white toward the end of
estrus); tail twitching; increased bleating (vocalization);
decrease in milk production; increased restlessness;
and frequent urination. Standing or riding are not
seen as heat signs in goats as often as in cows. Observation
around feeding and milking times is undesirable, because
the does have their mind not concentrated on est ++++MISSING
DATA++++
7 Estrus (heat) lasts from 12 to
48 hours, averaging 36 hours and ovulations occur
24 to 36 hours after onset of heat. Goats should be
bred naturally once 24 hours after onset of heat or
if conservation of the buck is not a consideration,
every 12 hours until the receptive period is over.
In artificial insemination, it is recommended to breed
every 12 hours, 2 to 3 times. Does generally have
heat cycles of 21 day length, similar to cows. However,
considerable variation between individual does exists
without any abnormality reason. The recurrence of
estrus cycles should be fairly consistent in an individual
animal. A doe with an unusual cycle length of 35 to
40 days should be suspected of embryo loss and should
be placed under careful observation.
8 A buck must be prepared for the
breeding season with good nutrition, parasite control,
foot trimming, etc. A prebreeding genital exam should
be carried out with examination of the testicles for
any abnormalities. The testicle should be plump, firm
and symmetrical. If any abnormalities or problems
are suspected, a semen evaluation should be carried
out. Many systemic debilitating diseases, arthritis,
foot rot, and scrotal infections can affect fertility
of bucks.
9 The Pregnant Doe Pregnancy diagnosis
should be done to ensure pregnancy has occurred and
if not, the situation corrected before the end of
the season. Gestation in goats is 150 days. Pregnancy
diagnosis continues to be a problem in small ruminants.
Nonreturn to estrus is the most commonly used sign
of pregnancy. This requires close observations and
can be adequate. If a buck is present, return to estrus
determination is simple.
10 Recto-abdominal palpation with
the aid of a rectal probe can be done with great caution
and experience from 70 to 110 days but many veterinarians
find it too dangerous to recommend. After 110 days
the fetuses can be palpated through the abdominal
wall. Ultra sound and radiography pregnosticators
are available but the initial expense is a limiting
factor.
11 Milk tests, e.g. available from
DHIA labs, can be used at 21 to 23 days post-breeding
to detect levels of the pregnancy hormone, progesterone.
Low levels indicate a non-pregnant status. However,
goat owners should keep in mind that an animal detected
as pregnant may later lose the fetus, because goats
may be more susceptible to abortion than cows, particularly
during the periods of poor nutrition.
12 Contagious reproductive diseases
are not a common problem in goats. Brucellosis caused
by B. melitensis is not found in the United States
although it is a problem in other parts of the world.
Goats are resistant to Brucella abortus, the brucellosis
of cows and it is not a problem. Enzootic abortion,
a chlamydial infection, occurs in California and causes
abortions. Characteristically 80 percent of abortions
occur in first and second fresheners and 3 to 4 weeks
before normal kidding. Natural immunity develops and
vaccination programs are effective in problem areas.
Whenever an abortion occurs, careful examination of
the aborted fetus(es) and placenta is essential by
submitting to a diagnostic pathology laboratory.
13 The Dry Doe The pregnant doe should
have a 60 day dry period prior to kidding and should
be gaining in condition for the last month before
kidding without fattening. Nutrition must be carefully
managed to provide the necessary nutrients balanced
so that no metabolic disorders such as ketosis and
milk fever may occur. About four and two weeks prior
to kidding an intramuscular administration of a selenium
treatment (Bo-Se) at the rate of 1 ml per 40 lb of
bodyweight is advisable in selenium deficient areas
such as the Northeast, Mid-Atlantic, Great Lakes,
East Coast, Florida, and Northwest areas in the US.
14 The Kidding Doe (Parturition)
Attendance at kidding is life saving and cleanliness
is very important. The fetus acquires the capacity
for extrauterine life only shortly before term, and
may die in utero if parturition is unduly delayed.
As kidding time approaches, the udder rapidly enlarges,
the pelvic ligaments relax around the tail head, and
the vulva becomes greatly enlarged. Eight to 12 hours
before birth, the cervix begins to dilate and the
cervical mucus plug will be in evidence, as a tan,
sticky substance smeared about the hind parts of the
doe. This first stage of kidding lasts 1 to 6 hours.
If progress stops, a vaginal exam with clean, well
lubricated hands is in order.
15 Normally the fetus enters the
birth canal and the doe starts an abdominal press.
The chorioallantoic sac is ruptured and the unbroken
amniotic sac (water bag) is then forced through the
vulva. Delivery of the kids usually occurs in a short
time once the water bag can be viewed. Kids may be
presented either with their front feet forward or
in posterior presentation where their rear feet are
presented first. The doe may rest between each kid
for a short period of time. Most does are best left
alone during parturition. Interference with parturition
of does kidding for the first time may result in the
doe rejecting the kids. It is important that does
lick the kids as soon as possible after they are born
as this indicates her acceptance of them. Dystocias
(difficult births) are rarely encountered.
16 If labor is prolonged for more
than one hour with no progress, a vaginal exam is
again indicated. With multiple births, more than one
fetus may be lodged in the pelvis. Careful sorting
is necesary before delivery is possible. The goat's
uterus is very fragile and prolonged manipulation
may result in uterine rupture. ''Ring womb'' occurs,
when, with prolonged labor, the cervix begins to contract,
making delivery impossible. Caesarean sections are
done with overlarge fetuses, monsters, ''Ring womb''
and other dystocia that might threaten the doe's life.
17 After parturition, the doe should
begin to lick the kids, and she may eat part of the
fetal membranes. There is no evidence for benefit
or harm from ingestion of the fetal membranes. Normal
kids will start trying to stand up immediately and
should be on their feet and nursing within a short
period of time. It is important that kids nurse the
doe as soon as possible after birth in order to get
the first milk or colostrum. It may be necessary occasionally
to help slow or weak kids to nurse. Kids navels should
be dipped in iodine solution. Retention of the fetal
membranes, a condition not uncommon in cows, seldom
occurs in goats. A retained placenta should be treated
conservatively with the exposed portions clipped off.
The placenta is discharged naturally 3-5 days if not
normally expelled within 6 hours after kidding. Systemic
antibiotics are indicated only if the doe shows signs
of illness.
18 Thorough disinfection of pens
after each delivery and especially after problems
is important for successful reproductive management.
Tetanus toxoid and enterotoxemia C and D bacterin
injections are advised after each delivery as well
as deworming. Colostrum feeding should be continued
to kids beyond the first hours after kidding for three
days. Excess colostrum can be frozen successfully
for later use in other kiddings. The fresh doe will
normally discharge a deep red, mucus-like material
called lochia for 7 to 14 days postpartum. Abnormal
is a large amount of bright red blood, foulsmelling
exudate, or pus.
19 The Intersex The most important
cause of infertility in dairy goats is the occurrence
of the hermaphroditism or intersex condition. Affected
animals are more frequently female genetically with
a normal female complement of chromosones (60,XX).
They may have a normal size vulva but an enlarged
clitoris and a short or atretic vagina. A penile clitoris
or even an ova testis may occur in does that appear
phenotypically female otherwise. A shortened penis,
hypospadias, or hypoplastic testes may also occur.
20 Both hermaphroditism and congenital
hypoplasia of the reproductive tract are related to
naturally hornless or polled goats and are more likely
to occur when both parents are polled. Breeding to
horned bucks will avoid the problem but breeding to
horned does can reduce the occurrence of intersex
sterility also. Breeding polled bucks to polled goats
may result in a shift to more males born and as many
as 20 hermaphroditic progeny. Hornlessness acts as
a simple dominant and intersex sterility may be its
pleiotropic effect on a recessive trait with incomplete
penetrance, although linkage has not been excluded.
The polled gene has a high frequency in Saanen but
is rare in Angoras. The management interest in absence
of horns needs to be balanced against losses due to
intersex and labor costs in manual dehorning.
21 Since hornlessness is dominant
over horned condition, it is of management value to
be able to distinguish phenotypically the heterozygous
goats from the homozygous polled animals. Recent French
studies have demonstrated that small differences in
the shapes and positions of the bony rudimentary hornknobs
can be identified in goats. For homozygous polled
males they are rounded and separate, while in heterozygous
goats the two knobs are of oval shape and in a partially
joined V-shaped position.
REPRODUCTIVE MANAGEMENT
COLLECTION;GOAT HANDBOOK
ORIGIN;United States
DATE_INCLUDED;June 1992
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