Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely.
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic, meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cases twins can have the same mother and different fathers.
Intensive pig farming, also known as pig factory farming, is the primary method of pig production, in which grower pigs are housed indoors in group-housing or straw-lined sheds, whilst pregnant sows are housed in gestation crates or pens and give birth in farrowing crates.
A maternal effect is a situation where the phenotype of an organism is determined not only by the environment it experiences and its genotype, but also by the environment and genotype of its mother. In genetics, maternal effects occur when an organism shows the phenotype expected from the genotype of the mother, irrespective of its own genotype, often due to the mother supplying messenger RNA or proteins to the egg. Maternal effects can also be caused by the maternal environment independent of genotype, sometimes controlling the size, sex, or behaviour of the offspring. These adaptive maternal effects lead to phenotypes of offspring that increase their fitness. Further, it introduces the concept of phenotypic plasticity, an important evolutionary concept. It has been proposed that maternal effects are important for the evolution of adaptive responses to environmental heterogeneity.
Dog breeding is the practice of mating selected dogs with the intention of maintaining or producing specific qualities and characteristics. When dogs reproduce without such human intervention, their offspring's characteristics are determined by natural selection, while "dog breeding" refers specifically to the artificial selection of dogs, in which dogs are intentionally bred by their owners. Breeding relies on the science of genetics, hence a breeder who is knowledgeable on canine genetics, health, and the intended purpose of the dogs attempts to breed suitable dogs.
Fetal pigs are unborn pigs used in elementary as well as advanced biology classes as objects for dissection. Pigs, as a mammalian species, provide a good specimen for the study of physiological systems and processes due to the similarities between many pig and human organs.
Parent–offspring conflict (POC) is an expression coined in 1974 by Robert Trivers. It is used to describe the evolutionary conflict arising from differences in optimal parental investment (PI) in an offspring from the standpoint of the parent and the offspring. PI is any investment by the parent in an individual offspring that decreases the parent's ability to invest in other offspring, while the selected offspring's chance of surviving increases.
Parental investment, in evolutionary biology and evolutionary psychology, is any parental expenditure that benefits offspring. Parental investment may be performed by both males and females, females alone or males alone. Care can be provided at any stage of the offspring's life, from pre-natal to post-natal.
Alloparenting is a term for any form of parental care provided by an individual towards young that are not its own direct offspring. These are often called "non-descendant" young, even though grandchildren can be among them. Among humans, alloparenting is often performed by a child's grandparents and older siblings. Individuals providing this care are called by the neutral term "alloparent".
The pig, also called swine or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus Sus. It is considered a subspecies of Sus scrofa by some authorities, but as a distinct species by others. Pigs were domesticated in the Neolithic, both in East Asia and in the Near East. When domesticated pigs arrived in Europe, they extensively interbred with wild boar but retained their domesticated features.
A litter is the live birth of multiple offspring at one time in animals from the same mother and usually from one set of parents, particularly from three to eight offspring. The word is most often used for the offspring of mammals, but can be used for any animal that gives birth to multiple young. In comparison, a group of eggs and the offspring that hatch from them are frequently called a clutch, while young birds are often called a brood. Animals from the same litter are referred to as littermates.
Siblicide is the killing of an infant individual by its close relatives. It may occur directly between siblings or be mediated by the parents, and is driven by the direct fitness benefits to the perpetrator and sometimes its parents. Siblicide has mainly, but not only, been observed in birds.
Cross-fostering is a technique used in animal husbandry, animal science, genetic and nature versus nurture studies, and conservation, whereby offspring are removed from their biological parents at birth and raised by surrogates, typically of a different species, hence 'cross.' This can also occasionally occur in nature.
Savaging is a term used in the study of ethology that refers to aggressive behaviour displayed by the mother towards the offspring. Aggressive behaviour includes being rough with, injuring, biting, attacking, crushing and killing of the offspring. While savaging behaviour has been seen in multiple species, it is predominantly demonstrated in domestic pigs. As the definition of savaging is so broad, research on the prevalence of savaging behaviour varies with reports of little savaging of offspring to savaging of offspring up to the 20th percentile. Prevalence of aggressive, non-fatal savaging is greater in gilts, or females who have not yet previously farrowed, as piglet-focused aggression is more frequent in young animals than sows, adult females who have previously given birth. Occurrence of savaging demonstrated by sows is greater if the sow has previously savaged her offspring either as a gilt or sow. Savaging behaviour usually occurs during the first two days after parturition. Prevalence of savaging is similar among first and second farrowing cycles. Savaging behaviour has a significant impact on both agricultural economy and animal welfare which is why it is currently a subject of interest in the pig industry.
The Javan warty pig, also called Javan wild pig, is an even-toed ungulate in the family Suidae. It is endemic to the Indonesian islands Java and Bawean, and is considered extinct on Madura. It is listed as Endangered on the IUCN Red List since 1996.
The Large Black is a British breed of domestic pig. It is the only British pig that is entirely black. It was created in the last years of the nineteenth century by merging the black pig populations of Devon and Cornwall in the south-west with those of Essex, Suffolk and Kent in the south-east. It is hardy, docile and prolific; it forages well and is suitable for extensive farming, but not well suited to intensive management.
Nesting behavior refers to an instinct in animals during reproduction to prepare a place with optimal conditions for offspring. The nesting place provides protection against predators and competitors that mean to exploit or kill offspring. It also provides protection against the physical environment.
A fetus or foetus is the unborn mammalian offspring that develops from an embryo. Following the embryonic stage, the fetal stage of development takes place. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, in general a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional, and some may not yet be situated in their final anatomical location.
The Middle White is a British breed of domestic pig. It originated in Yorkshire, and derived from the Large White and the now-extinct Small White. It was recognised in 1852, and the first herd-book was published in 1884. It is a porker, reared for fresh pork, and is characterised by a short and sharply-upturned snout. After the Second World War it came close to extinction; although numbers have recovered somewhat, it is listed by the Rare Breeds Survival Trust as "priority" – the highest level of risk.
Animals, including siblings, compete for resources such as food, territory, and potential mating partners. In animal sibling rivalry, individuals compete for parental care or limited resources, which can sometimes result in siblicide, the killing of siblings. Sibling rivalry occurs in many different forms. Siblings may compete for resources in a prenatal and/or post-birth environment. The degree of rivalry varies, ranging from a low level of violence in non-aggressive to the killing of kin in siblicide.
