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
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
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
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
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
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.