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69-483: The Hays Converter is a hardy beef cattle breed, meant to stand up to the harsh conditions in Alberta. They are equipped with strong legs and good feet, giving this breed increased hardiness. By appearance, they are generally black with some white markings on the face, legs and underbelly. They can also be red and white in colour, but this is a more rare occurrence. Cows typically weigh 1250 to 1500 pounds while bulls can reach

138-483: A butcher or packing house, with the finished carcass resulting in approximately 430 lb (200 kg) of beef. Depending on what cuts of meat are desired, there is a scale of marbled meat used to determine the quality. Marbling is the fat that is within the muscle, not around it. The more marbled a cut is, the higher it will grade and be worth. Slaughtering of livestock has three distinct stages: preslaughter handling, stunning, and slaughtering. The biggest concern

207-463: A 34–48% higher survival rate. Selection for growth in Penaeid shrimps yielded successful results. A selective breeding program for Litopenaeus stylirostris saw an 18% increase in growth after the fourth generation and 21% growth after the fifth generation. Marsupenaeus japonicas showed a 10.7% increase in growth after the first generation. Argue et al. (2002) conducted a selective breeding program on

276-578: A 4% increase after one generation and a 15% increase after two generations. Chilean oysters ( Ostrea chilensis ), selected for improvement in live weight and shell length showed a 10–13% gain in one generation. Bonamia ostrea is a protistan parasite that causes catastrophic losses (nearly 98%) in European flat oyster Ostrea edulis L. This protistan parasite is endemic to three oyster-regions in Europe. Selective breeding programs show that O. edulis susceptibility to

345-474: A bloodline superior in certain respects to the original base stock. Such animals can be recorded with a breed registry , the organization that maintains pedigrees and/or stud books . However, single-trait breeding, breeding for only one trait over all others, can be problematic. In one case mentioned by animal behaviorist Temple Grandin , roosters bred for fast growth or heavy muscles did not know how to perform typical rooster courtship dances, which alienated

414-420: A bull is released into a herd of cows approximately 55 days after the calving period, depending on the cows' body condition score (BCS). If it was a cow's first time calving, she will take longer to re-breed by at least 10 days. However, beef cattle can also be bred through artificial insemination , depending on the cow and the size of the herd. Cattle are normally bred during the summer so that calving may occur

483-422: A certain purpose, or may intend to use some type of crossbreeding to produce a new type of stock with different, and, it is presumed, superior abilities in a given area of endeavor. For example, to breed chickens, a breeder typically intends to receive eggs, meat, and new, young birds for further reproduction. Thus, the breeder has to study different breeds and types of chickens and analyze what can be expected from

552-479: A certain set of characteristics before he or she starts breeding them. Therefore, when purchasing initial breeding stock, the breeder seeks a group of birds that will most closely fit the purpose intended. Purebred breeding aims to establish and maintain stable traits, that animals will pass to the next generation. By "breeding the best to the best," employing a certain degree of inbreeding , considerable culling, and selection for "superior" qualities, one could develop

621-415: A day, and approximately 82 L in hot weather. They need a constant supply of good quality feed and potable water according to the 5 Freedoms of Animal Welfare. Most Beef cattle are finished in feedlots. The first feedlots were constructed in the early 1950s. Some of these feedlots grew so large they warranted a new designation, " Concentrated Animal Feeding Operation " (CAFO). Most American beef cattle spend

690-508: A high butter-fat content, allowing calves to grow faster. The Hereford cattle were chosen due to their high fleshing rate, meaning that their ability to mature quickly would also be passed onto their offspring. Lastly, the Brown Swiss cattle were chosen due to their perfectly shaped udder and ability to produce milk up until the end of lactation. Once the crosses began, Hays selected for the traits he wanted, and any offspring that did not make

759-490: A high output of carbon dioxide . Multiple global agencies and governments, including the United Nations , have cited beef production as a primary driver of climate change, and advise that a global reduction in meat consumption should be pursued. Cattle farming has also been blamed as one of the primary reasons for rapid deforestation in countries such as Brazil and Indonesia , causing habitat loss when deforested land

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828-436: A professional breeder , while domesticated plants are known as varieties , cultigens , cultivars , or breeds. Two purebred animals of different breeds produce a crossbreed , and crossbred plants are called hybrids . Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals. In animal breeding artificial selection

897-524: A scientific practice by Robert Bakewell during the British Agricultural Revolution in the 18th century. Arguably, his most important breeding program was with sheep. Using native stock, he was able to quickly select for large, yet fine-boned sheep, with long, lustrous wool. The Lincoln Longwool was improved by Bakewell, and in turn the Lincoln was used to develop the subsequent breed, named

966-525: A selected line of L. stylirostris that is resistant to IHHNV infection. Tang et al. (2000) confirmed this by showing no mortalities in IHHNV- challenged Super Shrimp post larvae and juveniles. Selective breeding programs for aquatic species provide better outcomes compared to terrestrial livestock. This higher response to selection of aquatic farmed species can be attributed to the following: Selective breeding in aquaculture provide remarkable economic benefits to

1035-410: A single, recognizable breed, and purebreds with recorded lineage are called pedigreed . Crossbreeds are a mix of two purebreds, whereas mixed breeds are a mix of several breeds, often unknown. Animal breeding begins with breeding stock, a group of animals used for the purpose of planned breeding. When individuals are looking to breed animals, they look for certain valuable traits in purebred stock for

1104-439: A specific trait can evolve in response to selection. A single-generation method of breeding is not as accurate or direct. The process is also more practical and easier to understand than sibling analysis. Selective breeding is better for traits such as physiology and behavior that are hard to measure because it requires fewer individuals to test than single-generation testing. However, there are disadvantages to this process. This

1173-559: A weight of 2300 to 2800 pounds. Hays Converters are an early maturing breed, this feature allows them to breed and produce offspring sooner than other breeds of cattle. Hays chose three particular breeds of cattle in order to achieve the optimal breed of cattle. He achieved this by combination crosses of Holstein cattle on Hereford cattle and Brown Swiss cattle. These three existing breeds were chosen specifically for certain traits they carried. The Holstein cattle were chosen due to their good strong feet and ability to produce milk with

1242-408: Is a stub . You can help Misplaced Pages by expanding it . Beef cattle Beef cattle are cattle raised for meat production (as distinguished from dairy cattle , used for milk production). The meat of mature or almost mature cattle is mostly known as beef . In beef production there are three main stages: cow-calf operations , backgrounding , and feedlot operations. The production cycle of

1311-405: Is a necessary component of selective breeding. Additionally, selective breeding can lead to a variety of issues including reduction of genetic diversity or physical problems. The process of selective breeding can create physical issues for plants or animals such as dogs selectively bred for extremely small sizes dislocating their kneecaps at a much more frequent rate then other dogs. An example in

1380-413: Is also used in research to produce transgenic animals that breed "true" (i.e., are homozygous ) for artificially inserted or deleted genes. Selective breeding in aquaculture holds high potential for the genetic improvement of fish and shellfish for the process of production. Unlike terrestrial livestock, the potential benefits of selective breeding in aquaculture were not realized until recently. This

1449-457: Is because a single experiment done in selective breeding cannot be used to assess an entire group of genetic variances, individual experiments must be done for every individual trait. Also, due to the necessity of selective breeding experiments to require maintaining the organisms tested in a lab or greenhouse , it is impractical to use this breeding method on many organisms. Controlled mating instances are difficult to carry out in this case and this

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1518-409: Is because high mortality led to the selection of only a few broodstock , causing inbreeding depression, which then forced the use of wild broodstock. This was evident in selective breeding programs for growth rate, which resulted in slow growth and high mortality. Control of the reproduction cycle was one of the main reasons as it is a requisite for selective breeding programs. Artificial reproduction

1587-541: Is limited. Once restrained the animal can be stunned in one of three methods: penetrating captive bolt , non-penetrating captive bolt, and gunshot. Most abattoirs use captive bolts instead of guns. Stunning ensures the animal feels no pain during slaughtering and reduces the animals stress, therefore increasing the quality of meat. The final step is slaughtering. Typically the animal will be hung by its back leg and its throat will be slit to allow exsanguination . The hide will be removed for further processing at this point and

1656-579: Is meat production, other uses include leather , and beef by-products used in candy , shampoo , cosmetics , and insulin . Besides breeding to meet the demand for beef production, owners also use selective breeding to attain specific traits in their beef cattle. An example of a desired trait could be leaner meat or resistance to illness. Breeds known as dual-purpose are also used for beef production. These breeds have been selected for two purposes at once, such as both beef and dairy production, or both beef and draught . Dual-purpose breeds include many of

1725-458: Is not uncommon for fish to escape the nets or pens that they are kept in, especially in mass. If these fish are farmed in areas they are not native to they may be able to establish themselves and outcompete native populations of fish, and cause ecological harm as an invasive species. Furthermore, if they are in areas where the fish being farmed are native too their genetics are selectively bred rather than being wild. These farmed fish could breed with

1794-533: Is often combined with techniques such as inbreeding , linebreeding , and outcrossing . In plant breeding , similar methods are used. Charles Darwin discussed how selective breeding had been successful in producing change over time in his 1859 book, On the Origin of Species . Its first chapter discusses selective breeding and domestication of such animals as pigeons , cats , cattle , and dogs . Darwin used artificial selection as an analogy to propose and explain

1863-406: Is preslaughter handling: how the animal is treated before it is stunned and slaughtered. Stress at this time can cause adverse effects on the meat, but water access and lower stocking densities have been allowed to minimize this. However, access to feed is restricted for 12–24 hours prior to slaughtering for ease of evisceration . Stunning is done when the animal is restrained in a chute so movement

1932-475: Is used either as pasture or to grow feed crop . Selective breeding Selective breeding (also called artificial selection ) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds , normally bred by

2001-584: The English Leicester (or Leicester Longwool), which is primarily kept for wool production. Bakewell was also the first to breed cattle to be used primarily for beef. Previously, cattle were first and foremost kept for pulling ploughs as oxen , but he crossed long-horned heifers and a Westmoreland bull to eventually create the Dishley Longhorn . As more and more farmers followed his lead, farm animals increased dramatically in size and quality. In 1700,

2070-530: The Zebu breeds of India such as Tharparkar and Ongole Cattle . There are multiple continental breeds that were bred for this purpose as well. The original Simmental / Fleckvieh from Switzerland is a prime example. Not only are they a dual-purpose breed for beef and dairy, but in the past they were also used for draught. However, throughout the generations, the breed has diverged into two groups through selective breeding . Most beef cattle are mated naturally, whereby

2139-610: The 1859 first edition of his work On the Origin of Species , in Chapter IV: Natural Selection, and in Chapter VI: Difficulties on Theory: Slow though the process of selection may be, if feeble man can do much by his powers of artificial selection, I can see no limit to the amount of change, to the beauty and infinite complexity of the co-adaptations between all organic beings, one with another and with their physical conditions of life, which may be effected in

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2208-594: The Canadian National Farm Animal Care Council, beef cattle must have access to shelter from extreme weather, safe handling and equipment, veterinary care and humane slaughter. If an animal is infected or suspected to have an illness, it is the responsibility of the owners to report it immediately to a practicing veterinarian for either treatment or euthanasia. Depending on a multitude of factors (season, type of production system, stocking density, etc.), illness and disease can spread quickly through

2277-446: The New (or Dishley) Leicester. It was hornless and had a square, meaty body with straight top lines. These sheep were exported widely, including to Australia and North America , and have contributed to numerous modern breeds, despite the fact that they fell quickly out of favor as market preferences in meat and textiles changed. Bloodlines of these original New Leicesters survive today as

2346-531: The Pacific White Shrimp, Litopenaeus vannamei at The Oceanic Institute, Waimanalo, USA from 1995 to 1998. They reported significant responses to selection compared to the unselected control shrimps. After one generation, a 21% increase was observed in growth and 18.4% increase in survival to TSV. The Taura Syndrome Virus (TSV) causes mortalities of 70% or more in shrimps. C.I. Oceanos S.A. in Colombia selected

2415-606: The Ropsha carp. The results showed a 30–40% to 77.4% improvement of cold tolerance but did not provide any data for growth rate. An increase in growth rate was observed in the second generation in Vietnam. Moav and Wohlfarth (1976) showed positive results when selecting for slower growth for three generations compared to selecting for faster growth. Schaperclaus (1962) showed resistance to the dropsy disease wherein selected lines suffered low mortality (11.5%) compared to unselected (57%). Growth

2484-897: The United States, Nutrient Requirements of Beef Cattle , has been through eight editions over at least seventy years. The 1996 seventh edition substituted the concept of metabolizeable protein for the sixth edition's crude protein . In the 20th century, Canadian practice followed the American guidance. Already in 1970, the Food and Drug Administration was regulating pharmaceutical supplements in beef cattle feed such as hormones and prophylactic antibiotics . Some animals live on pasture their entire lives and therefore only experience fresh grass; these are typically cow-calf operations in more tropical climates. Backgrounded calves and feedlot animals tend to have different diets that contain more grain than

2553-423: The animal will be broken down with evisceration and decapitation . The carcass will be placed in a cooler for 24–48 hours prior to the meat being cut. Cattle farming is one of the most emissive forms of food generation, and least effective uses of land and water as resources. Cattle emit large amounts of methane resulting from their digestive process, and the process of preparing and transporting beef results in

2622-426: The animals starts at cow-calf operations; this operation is designed specifically to breed cows for their offspring. From here the calves are backgrounded for a feedlot . Animals grown specifically for the feedlot are known as feeder cattle , the goal of these animals is fattening. Animals not grown for a feedlot are typically female and are commonly known as replacement heifers . While the principal use of beef cattle

2691-569: The average weight of a bull sold for slaughter was 370 pounds (168 kg). By 1786, that weight had more than doubled to 840 pounds (381 kg). However, after his death, the Dishley Longhorn was replaced with short-horn versions. He also bred the Improved Black Cart horse, which later became the Shire horse . Charles Darwin coined the term 'selective breeding'; he was interested in

2760-427: The book Botany of Desire where Michael Pollan shows the connection between basic human desires through four different plants: apples for sweetness, tulips for beauty, cannabis for intoxication, and potatoes for control. In a form of reciprocal evolution humans have influenced these plants as much as the plants have influenced the people that consume them, is known as coevolution . Selective plant breeding

2829-496: The cut in one way or another would have their tails docked and were shipped off to a processing plant. Once all desired traits were achieved in the offspring, the breed was closed off to mating with any outside breeds. By the time the breed achieved pedigree status in 1975, it had achieved all of the traits Hays had hoped it would. These traits included high growth rate, sturdy build, good carcass quality, easy calving and excellent milk production. This cattle -related article

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2898-438: The domestication of wild plants into uniform and predictable agricultural cultigens . These high-yielding varieties have been particularly important in agriculture. As crops improved, humans were able to move from hunter-gatherer style living to a mix of hunter-gatherer and agriculture practices. Although these higher yielding plants were derived from an extremely primitive version of plant breeding, this form of agriculture

2967-409: The eastern oyster, Crassostrea virginica , for resistance against co-occurring parasites Haplosporidium nelson (MSX) and Perkinsus marinus (Dermo). They achieved dual resistance to the disease in four generations of selective breeding. The oysters showed higher growth and survival rates and low susceptibility to the infections. At the end of the experiment, artificially selected C. virginica showed

3036-686: The fish for four generations, spawning dates were 13–15 days earlier. Cyprinids Selective breeding programs for the Common carp ( Cyprinus carpio ) include improvement in growth, shape and resistance to disease. Experiments carried out in the USSR used crossings of broodstocks to increase genetic diversity and then selected the species for traits like growth rate, exterior traits and viability, and/or adaptation to environmental conditions like variations in temperature. Kirpichnikov et al. (1974) and Babouchkine (1987) selected carp for fast growth and tolerance to cold,

3105-470: The following spring. However, cattle breeding can occur at other times of year. Depending on the operation, calving may occur all year round. Owners can select the breeding time based on a number of factors, including reproductive performance, seasonal cattle pricing and handling facilities. Cattle handlers are expected to maintain a low-stress environment for their herds, involving constant safety, health, comfort, nourishment and humane handling. According to

3174-436: The herd from animal to animal. Owners are expected to monitor their cattle's condition regularly for early detection and treatment, as some cattle illnesses can threaten both cattle and human health (known as zoonotic ) as witnessed with Mad cow disease and Tuberculosis . On average, cattle will consume 1.4 to 4% of their body weight daily. There is a range of types of feed available for these animals. The standard text in

3243-400: The idea in his book titled India , which included various examples. The agriculturist selects his corn, letting grow as much as he requires, and tearing out the remainder. The forester leaves those branches which he perceives to be excellent, whilst he cuts away all others. The bees kill those of their kind who only eat, but do not work in their beehive. Selective breeding was established as

3312-411: The idea of "farmers" experimenting with agriculture. In addition, the ability for humans to stay within one place for food and create permanent settlements made the process move along faster. During this transitional period, crops began to acclimate and evolve with humans encouraging humans to invest further into crops. Over time this reliance on plant breeding has created problems, as highlighted by

3381-452: The increasing demands of growing populations. Conversely, selective breeding within aquaculture can create problems within the biodiversity of both stock and wild fish, which can hurt the industry down the road. Although there is great potential to improve aquaculture due to the current lack of domestication, it is essential that the genetic diversity of the fish are preserved through proper genetic management, as we domesticate these species. It

3450-491: The industry, the primary one being that it reduces production costs due to faster turnover rates. When selective breeding is carried out, some characteristics are lost for others that may suit a specific environment or situation. This is because of faster growth rates, decreased maintenance rates, increased energy and protein retention, and better feed efficiency. Applying genetic improvement programs to aquaculture species will increase their productivity. Thus allowing them to meet

3519-589: The infection differs across oyster strains in Europe. A study carried out by Culloty et al. showed that 'Rossmore' oysters in Cork harbour, Ireland had better resistance compared to other Irish strains. A selective breeding program at Cork harbour uses broodstock from 3– to 4-year-old survivors and is further controlled until a viable percentage reaches market size. Over the years 'Rossmore' oysters have shown to develop lower prevalence of B. ostreae infection and percentage mortality. Ragone Calvo et al. (2003) selectively bred

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3588-473: The intentional selection of larger seeds. Most likely, there has been an interdependence between natural and artificial factors that have resulted in plant domestication. Selective breeding of both plants and animals has been practiced since early prehistory ; key species such as wheat , rice , and dogs have been significantly different from their wild ancestors for millennia, and maize , which required especially large changes from teosinte , its wild form,

3657-405: The last half of their lives in a CAFO. A steer that weighs 1,000 lb (450 kg) when alive makes a carcass weighing approximately 615 lb (280 kg) once the blood, head, feet, skin, offal and guts are removed. The carcass is then hung in a cold room for between one and four weeks, during which time it loses some weight as water dries from the meat. It is then deboned and cut by

3726-663: The long course of time by nature's power of selection. We are profoundly ignorant of the causes producing slight and unimportant variations; and we are immediately made conscious of this by reflecting on the differences in the breeds of our domesticated animals in different countries,—more especially in the less civilized countries where there has been but little artificial selection. Animals with homogeneous appearance, behavior, and other characteristics are known as particular breeds or pure breeds, and they are bred through culling animals with particular traits and selecting for further breeding those with other traits. Purebred animals have

3795-409: The natives which could be problematic In the sense that they would have been bred for consumption rather than by chance. Resulting in an overall decrease in genetic diversity and rendering local fish populations less fit for survival. If proper management is not taking place then the economic benefits and the diversity of the fish species will falter. Selective breeding is a direct way to determine if

3864-403: The pasture type. Grain is more expensive than pasture but the animals grow faster with the higher protein levels. Since cattle are herbivores and need roughage in their diet, silage , hay and/or haylage are all viable feed options. Despite this, 3/4th of the 32 pounds (14.52 kg) of feed cattle consume each day will be corn. Cattle weighing 1000 lbs. will drink an average of 41 L

3933-507: The performance of select Atlantic salmon with wild fish was conducted by AKVAFORSK Genetics Centre in Norway. The traits, for which the selection was done included growth rate, feed consumption, protein retention, energy retention, and feed conversion efficiency. Selected fish had a twice better growth rate, a 40% higher feed intake, and an increased protein and energy retention. This led to an overall 20% better Fed Conversion Efficiency as compared to

4002-548: The plant world is the Lenape potatoes were selectively bred for their disease or pest resistance which was attributed to their high levels of toxic glycoalkaloid solanine which are usually present only in small amounts in potatoes fit for human consumption. When genetic diversity is lost it can also allow for populations to lack genetic alternatives to adapt to events. This becomes an issue of biodiversity, because attributes are so wide-spread they can result in mass epidemics. As seen in

4071-420: The process as an illustration of his proposed wider process of natural selection . Darwin noted that many domesticated animals and plants had special properties that were developed by intentional animal and plant breeding from individuals that showed desirable characteristics, and discouraging the breeding of individuals with less desirable characteristics. Darwin used the term "artificial selection" twice in

4140-887: The roosters from hens and led the roosters to kill the hens after mating with them. A Soviet attempt to breed lab rats with higher intelligence led to cases of neurosis severe enough to make the animals incapable of any problem solving unless drugs like phenazepam were used. The observable phenomenon of hybrid vigor stands in contrast to the notion of breed purity. However, on the other hand, indiscriminate breeding of crossbred or hybrid animals may also result in degradation of quality. Studies in evolutionary physiology , behavioral genetics , and other areas of organismal biology have also made use of deliberate selective breeding, though longer generation times and greater difficulty in breeding can make these projects challenging in such vertebrates as house mice . The process of plant breeding has been used for thousands of years, and began with

4209-515: The survivors of the disease from infected ponds and used them as parents for the next generation. They achieved satisfying results in two or three generations wherein survival rates approached levels before the outbreak of the disease. The resulting heavy losses (up to 90%) caused by Infectious hypodermal and haematopoietic necrosis virus (IHHNV) caused a number of shrimp farming industries started to selectively breed shrimps resistant to this disease. Successful outcomes led to development of Super Shrimp,

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4278-568: The theory of natural selection but distinguished the latter from the former as a separate process that is non-directed. The deliberate exploitation of selective breeding to produce desired results has become very common in agriculture and experimental biology. Selective breeding can be unintentional, for example, resulting from the process of human cultivation; and it may also produce unintended – desirable or undesirable – results. For example, in some grains, an increase in seed size may have resulted from certain ploughing practices rather than from

4347-621: The wild stock. Atlantic salmon have also been selected for resistance to bacterial and viral diseases. Selection was done to check resistance to Infectious Pancreatic Necrosis Virus (IPNV). The results showed 66.6% mortality for low-resistant species whereas the high-resistant species showed 29.3% mortality compared to wild species. Rainbow trout ( S. gairdneri ) was reported to show large improvements in growth rate after 7–10 generations of selection. Kincaid et al. (1977) showed that growth gains by 30% could be achieved by selectively breeding rainbow trout for three generations. A 7% increase in growth

4416-417: Was an investment that the people who grew them were planting then could have a more varied diet. This meant that they did not completely stop their hunting and gathering immediately but instead over time transition and ultimately favored agriculture. Originally this was due to humans not wanting to risk using all their time and resources for their crops just to fail. Which was promptly called play farming due to

4485-440: Was not achieved because of the difficulties in hatching or feeding some farmed species such as eel and yellowtail farming. A suspected reason associated with the late realization of success in selective breeding programs in aquaculture was the education of the concerned people – researchers, advisory personnel and fish farmers. The education of fish biologists paid less attention to quantitative genetics and breeding plans. Another

4554-564: Was recorded per generation for rainbow trout by Kause et al. (2005). In Japan, high resistance to IPNV in rainbow trout has been achieved by selectively breeding the stock. Resistant strains were found to have an average mortality of 4.3% whereas 96.1% mortality was observed in a highly sensitive strain. Coho salmon ( Oncorhynchus kisutch ) increase in weight was found to be more than 60% after four generations of selective breeding. In Chile, Neira et al. (2006) conducted experiments on early spawning dates in coho salmon. After selectively breeding

4623-478: Was seen to increase by 12–20% in selectively bred Iictalurus punctatus . More recently, the response of the Channel Catfish to selection for improved growth rate was found to be approximately 80%, that is, an average of 13% per generation. Selection for live weight of Pacific oysters showed improvements ranging from 0.4% to 25.6% compared to the wild stock. Sydney-rock oysters ( Saccostrea commercialis ) showed

4692-623: Was selectively bred in Mesoamerica . Selective breeding was practiced by the Romans . Treatises as much as 2,000 years old give advice on selecting animals for different purposes, and these ancient works cite still older authorities, such as Mago the Carthaginian . The notion of selective breeding was later expressed by the Persian Muslim polymath Abu Rayhan Biruni in the 11th century. He noted

4761-680: Was the failure of documentation of the genetic gains in successive generations. This in turn led to failure in quantifying economic benefits that successful selective breeding programs produce. Documentation of the genetic changes was considered important as they help in fine tuning further selection schemes. Aquaculture species are reared for particular traits such as growth rate, survival rate, meat quality, resistance to diseases, age at sexual maturation, fecundity, shell traits like shell size, shell color, etc. Gjedrem (1979) showed that selection of Atlantic salmon ( Salmo salar ) led to an increase in body weight by 30% per generation. A comparative study on

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