A goat is also a viviparous animal that carries its young inside their womb until birth. Everything about goat gestation, estrous cycle, pregnancy, and kidding is explained in this article.
Goat Estrous Cycle
The estrous cycle of goats is the period between one estrus (heat) and the next, which offers the doe (female goat) repeated opportunities to become pregnant. The goat estrous cycle lasts for 21 days on average, with a difference of 1 to 3 days. The goat estrous cycle could be interrupted by different physiological reasons such as pregnancy, lactation or photo-period, periods of inadequate nutrition or stressful environmental conditions. The cycle can also be interrupted by reproductive pathologies such as uterine infections, persistent corpus luteum, mummified fetuses, etc.
The estrous cycle comprises four (4) stages, which are Proestrus; Estrus; Metestrus; Diestrus.
- Proestrus: Here, follicular growth takes place with increased levels of follicle-stimulating hormone (FSH) and decreasing estrogens. At this stage, there is clear mucus production by the vagin.a. Proestrus lasts between 30 and 60 hours.
- Estrus: Estrus is the period of sexual receptivity and copulation. Estrus is then the stage in which the maturation and rupture of the follicles occur. It is the heat period of the animal, and it is the moment in which the female accepts the male and the female’s uterus is prepared to receive the egg and sperm. The doe will continue to allow the bucks (male goats) to mount her for 30 hours after heat is detected. In goats, ovulation is spontaneous and occurs towards the end of the estrus. Ovulation is the process of follicular rupture and exit of the ovum from the follicle. Estrus lasts between 18 and 36 hours.
- Metestrus: In this phase where the animal “ceases its heat” and the corpus luteum grows in the place that the follicle previously occupied, producing luteinizing hormone (LH) and progesterone at high levels, preventing the formation of other follicles. This period is best for the implantation of the fertilized egg and for its during the first half of pregnancy. Then, the corpus luteum remains and the doe will not enter another heat during the 5 months that the gestation will last.
- Diestrus: It is the longest and last phase of the estrous cycle. If pregnancy occurs, this phase continues throughout gestation, making marked changes in the uterus for the implantation of the egg with very dense milk production. If there is no pregnancy, the unfertilized egg comes out together with the fluids that were formed in the uterus. The corpus luteum is then destroyed to allow the growth of other follicles and the maturation of other eggs.
Anestrus is the period when the entire female reproductive system is inactive until the next reproductive season (5-6 months).
Characteristic Signs of Estrus in Goats
Female goats show signs of heat every 18 to 21 days and each heat period lasts for 24 to 36 hours. The goats of certain breeds show heat throughout the year, while the females of other breeds only show it during a certain season. This is related to the origin of the breed and the number of light hours per day.
The signs shown by a goat in heat include:
- Nervousness or restlessness
- Riding other goats and accepting to be mounted
- Frequent wagging tail
- Frequent bleating
- Reddish, wet and swollen vul.va
- Mucous discharges from the vul.va
- Clear, frequent urine in the presence of a male
- Loss of appetite
- If lactating, milk production decreases sharply
Goat Gestation Period
How Long is a Goat Pregnant?
The gestation period for goats is 145 to 155 days counting from the first day of mating. Goats have an average gestation period of 150 days. This simply means that a pregnant doe should kid in 150 days. Some factors like body size, breed and number of fetuses affect goat gestation period or length.
☛ Check This Out: Goat Gestation Calculator and Chart
Signs of Pregnancy in Goats
Detecting or identifying if a goat is pregnant may be difficult for some goat breeders, especially new breeders. However, it is easy to identify a pregnant goat through the following signs:
- No estrus or heat. Estrus or heat is one of the things used to determine the pregnancy status of an animal. The heat or estrus cycle in goats is 18 to 24 days (average of 21 days). This means a doe will only allow a buck to mount on whenever she is in heat. If eventually there is no mating or fertilization didn’t occur, the doe will come into heat after 21 days. If a doe still comes into heat, it means the goat is not pregnant. However, if it is observed that a goat has refused to come on another heat after 21 days of the last estrus, it indicates that the goat may be pregnant.
- Changes in feeding pattern and appetite: A pregnant doe will usually experience changes in the way she eats. She may eat more or less than she usually does. So if this happens in a female goat, there is no need to worry. However, if the goat is losing a lot of appetite, a veterinarian should be contacted.
- Swollen abdomen and udder. Twelve weeks after conception, the abdomen of a pregnant goat will starts to swelling at the side because the fetus(es) has increased in size. For a goat that has kidded before, the abdomen becomes saggy. The udder of a pregnant doe will also grow bigger around the same time that the abdomen swelled. In the case of dairy goats, the growing udder is sometimes less visible, because the udder is still swollen due to the milk it gives until the third month of pregnancy.
- Behavioral changes: Pregnant goats usually experience swings in their behaviors, influenced by the progesterone hormone. A pregnant goat may suddenly start isolating herself from the herd. She may suddenly become irritated and wouldn’t want anyone to touch or play with her. On another day, she may decide to play with everyone or jumping around.
Kidding is the process of giving birth to kids in goats. The nutrition of the doe in the pre-partum period is important and should be taken seriously. An increased level of feeding must be maintained during the last 6 weeks of pregnancy since undernourishment at the end of pregnancy could cause premature birth, or giving birth to small and weaker kids.
Signs of Labor in Goats
Two or three weeks before kidding, some anatomical changes are observed in the pregnant doe, such as marked swelling of the mammary gland. In the 24 to 48 hours before delivery, a relaxation of the pelvic ligaments, swelling and lengthening of the vul.va, changes in the state of the cervical mucus plug and a hardening of the mammary gland due to the “lowering of milk” will occur.
Other signs of labor in goats are:
- The goat becomes restless and scratches the ground
- Both sides of the tail are sunk into the goat
- Separates from the flock
- Shows affection
- Enlargement of the mammary gland with the production of thick, yellow, viscous liquid called the colostrum
- Loss of appetite
- Swelling of the vul.va with mucus discharge
- The goat at kidding is more nervous, vocalizes frequently and separates from the rest of the herd if it has a chance.
Stages of Labor in Goats
When labor begins, the female is very restless, with an increase in heart and respiratory rates. She isolates from the herd; she lies down, stands up, and begins with regular uterine contractions in a craniocaudal direction. These signs are part of the first stage of labor (dilation), in which the opening of the cervix occurs, and later the chorioallantoic fluid leaks out through the vul.va.
In the second stage (expulsion), the distension of the cervix and vagin.a provokes a neurohumoral reflex (Ferguson’s reflex) that causes an increase in abdominal contractions (pushes) and the release of oxytocin, which intensifies myometrial contractions.
Expulsion of the Fetus
The first bag, containing water, is observed and it breaks immediately, followed by a second which contains amniotic fluid. Contractions and expulsion efforts are manifested. The maximum time that taken after the rupture of the bags is two hours.
These are painful, causing restlessness and discomfort to the female who lies down, stands up, looks at the flank, etc. Then the amnion (water bag) appears and it breaks, freeing the fetus to be expelled. The female adopts the lateral decubitus position with the extremities extended; the moment of greatest effort coincides with the exit of the head and the thorax. The umbilical cord is cut when the fetus passes through the birth canal or when the female stands up.
The third stage involves the expulsion of the placenta, which is useless for a mother once the kid(s) is born. The duration of labor in goats is highly variable (1 or 2 hours), depending on the number of fetuses, their size, presentation in the birth canal, the mother’s state and age.
Number of Kids
Goats usually give birth to 1-3 kids per birth. Most goat breeds give birth to one kid at their first kidding.
Immediately after delivery, the goat will lick the kid to clean and stimulate it and may eat the placenta. After kidding, constant uninterrupted contact between the new mother and newborn with many licks and sniffs by the goat is required.