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Guinea pigs are a species of mammals of the order Rodentia and the family Caviidae. They are popular as pets. Like other mammals, they are sexually dimorphic, and females give birth to live young and feed them with milk from their mammary glands. They also have sex cycles that are different from periods. However, unlike humans, monkeys and 9 other primate species, 4 species of bats, shrews, barbed mice and dogs, they do not bleed like they do with the menstrual cycle.
Read on to learn more about the estrous cycle of female guinea pigs and how it differs from that of the 18 menstruating mammals.
Breeding guinea pig
Female guinea pigs can be fertile at 4 weeks of age, although they reach sexual maturity at 67 days and males at 56-76 days. Pigs breed all year round and can give birth to 5 litters in one year, the peak comes in the spring. Newborn baby sea puppies develop early, meaning they are born well-developed, mobile, and can eat solid food while breastfeeding. Sows become fertile 6 to 48 hours after giving birth.
Pregnancy lasts from 59 days (1.9 months) to 72 days (2.4 months), with an average of 63–68 days. Litter size from 1 to 6, on average 3 and from 2 to 4 individuals. 9 is the largest registered litter.
Scientific name of domestic guinea pig Cavia porcellus… The closest wild relative or ancestor is the mountain guinea pig, Cavia tschudii… The mountain guinea pig has a gestation period of 63 days, litter sizes range from one to four, and young guinea pigs mature in 2 months. Also closely related Guinea pig (wild guinea pig) and Galea musteloides (yellow-toothed sea).
The estrous cycle of a female guinea pig
Female guinea pigs are fertile for 6 to 11 hours, and usually during the night for 20 hours when ovulation occurs. They usually have estrus 3-4 times a year. Their estrous cycle lasts about 16 days. This is also known as estrus, although unlike the menstrual cycle, there are no periods or bleeding, and they occur spontaneously rather than regularly.
All female mammals have a sex cycle, or menstrual cycle. However, even between two closely related rodent species, such as the mountain guinea pig, wild guinea pig, and yellow-toothed guinea pig, they have different estrous cycles, as well as different social and mating systems. For example, wild guinea pig and mountain guinea pig have a long-term polygynous mating system in which one male protects several females from other males, but both sexes of yellow-toothed guinea pigs change between multiple partners. Domestic female guinea pigs and toothed ladies have periods of spontaneous hunting and ovulation, while yellow-toothed individuals have periods of estrus caused by the presence of a male, and then spontaneous ovulation. Domestic guinea pigs do not have seasonal mating cycles.
Typical reproduction of mammals
Mammals can give birth to both helpless and helpless young, early or well developed. Mammals are more likely to give birth to altricial offspring and several at the same time, while early-developed offspring tend to be born with fewer siblings. Having multiple offspring at a time was an evolutionary strategy for most mammals, which could increase the chances of survival of their altric offspring by having a large number of them.
Typical estrous cycle in mammals
The stages of a typical mammalian estrous cycle are as follows:
- Proestrus when the follicles of the endometrium and ovaries begin to develop. It also happens when female mammals who have a menstrual cycle or period, such as dogs, experience bleeding or pink discharge.
- Estrus known as estrus with increased susceptibility to men. At this stage, females only release pheromones.
- Metestrus this is when the corpus luteum is formed and mating does not occur.
- Diestrus this is when the corpus luteum is fully functional and the concentration of progesterone in the blood increases.
Why did some female mammals develop menstruation?
The 18 female mammalian species that have a menstrual cycle or period do not have an estrous cycle like most other mammals. But humans are even different from other mammals that give birth to altrial babies because they don’t give birth in litters. This smaller number of pups, usually one to two at a time, along with the larger size of the pups, makes them secondary and more akin to the premature species. The rapid development and large size of young people do not reflect the same level of maturity, so they remain helpless at birth.
Like other female mammals who bleed during their menstrual cycle or period, humans have a hemochorial placenta. This type of placenta allows fewer offspring to be born with a higher chance of survival, and also gives young people direct access to the mother’s blood supply. The endometrium of these mammals in the process of evolution has become thick and rigid, which does not allow placental implantation of weak or non-viable embryos. As a result, it became necessary to exfoliate the entire surface layer of the endometrium whenever successful fertilization and a healthy embryo did not occur after ovulation. Thus, menstrual bleeding has become an evolutionary strategy to match the unique hemochorial placenta.
Mammals with an estrous rather than a menstrual cycle simply reabsorb the endometrium after unsuccessful fertilization. Species such as dogs have a hemochorial placenta and bleeding that is equivalent to the menstrual cycle, for example, in humans, but their menstrual stages correspond to a typical estrous cycle and occur not once a month, but two to four times a year. …
Female guinea pigs have sexual cycles in which they enter heat several times a year for several days, with different stages. However, they do not experience bleeding or menstruation as they do during the menstrual cycle. During estrus, they are fertile and spontaneously ovulate. This type of estrous cycle is common in most mammals.
Next: 10 birds that mate for life
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