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PARAMETER GENETIK

PARAMETER GENETIK. Genetic parameters (h 2 , r dan r G ). Variable/ trait : 1. Coat color 2. Horn/hornless Animal power (work/ plough in paddy field) 4. Milk production, number of progeny. Genetic : breed, genetic group, linebred

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PARAMETER GENETIK

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  1. PARAMETER GENETIK Genetic parameters (h2 , r danrG )

  2. Variable/ trait : • 1. Coat color • 2. Horn/hornless • Animal power (work/ plough in paddy field) • 4. Milk production, number of progeny Genetic : breed, genetic group, linebred Environment : feed, food, wind, humidity, temperature, light, insect G x E interaction : breed-level of feed, group-Temp.humid

  3. GENETIC PARAMETER (PARAMETER GENETIK) (heritabilitas/ heritability, ripitabilitas/ repeatability, korelasi genetik/ genetic correlation) What is heritability? Heritability can be defined as the efficiency of transmission of superiority (or inferiority) of a trait from parents to offspring. It is usually expressed as a percentage ranging from 0%-100%, or as a decimal number ranging from 0 to 1. • Trait : • - Quantitative traits (milk, meat, egg, work, wool, power, IQ etc) • A matter of variance : • VP= VG+ VE+ VGxE P = G + E + GxE Fenotipe = genetik + lingkungan + interaksi genetik-lingkungan

  4. HERITABILITAS

  5. Traits that are 100% heritable If a trait is 100% heritable, then the full expression of the parents’ trait will be expressed in or by the off-spring. A trait that is 100% heritable would truly be a case of 'what you see is what you get' as 100% of the trait or genotype will be expressed in the animal’s phenotype, or the way the animal looks. There are a great many other traits that we take for granted as being 100% heritable. Under normal circumstances, many physical traits such as number of fingers on a human hand or the number of legs on the body of cattle are 100% heritable. A person's phenotype may be affected by the environment, for example, if an arm is amputated as a result of an accident, but the genes that an amputee carries in his/her gametes mean that any offspring will still be born with both arms. Other physical traits, such as height in humans or weight gain in cattle, are not 100% heritable. If this were the case every brother or sister in any species would be exactly the same height. The heritability of height is less than 100%.

  6. Heritability formula : • h2 = VG/ VP • V : variance (δ2) • Data daily weight gain in cattle (kg) : • 0.6 6. 0.45 • 0.7 7. 0.55 • 0.8 8. 0.65 Mean ? Variance ? • 0.5 9. 0.75 • 5. 0.75 10. 0.40 • Mean : X = 6.15/10 = 0.615 kg • Variance : s2 = [(0.6-0.615)2 + (0.7-0.615)2 + …… (0.40-0.615)2]/9 • = 0.0189 • s = 0.1375

  7. R = (Vg + Vep)/ VP REPEATABILITY (R) • The ability to repeat expression of particular trait on the future/ next production period • Correlation between (2 periods), or among (3 or more periods) measurements • Examples : • Cow no. : 1st lact. (100kg) : 2nd lact. (100kg) : • 1 50 55 • 2 60 62 • 3 58 59 • 4 62 62.5 • 5 56 58 R ?

  8. GENETIC CORRELATION ( rG ) • Correlation between 2 traits on different generation • - trait 1 on parent generation and trait 2 on the next • generation • It is caused by : • - pleiotropic gene (1 gene influence 2/ more traits) • - linkage of genes (unreal genetic correlation) • Examples : • - milk yield with % fat (negatif) • - weaning weight with post weaning gain (positif) • - birth weight with litter size (in swine/ negatif)

  9. Some traits, such as hair color, are determined by only a few genetic loci. The inheritance of such traits is relatively easy to predict, and the different phenotypes tend to occur in qualitatively distinct states (such as "black" and "red"). Other traits, usually called quantitative traits, may be influenced by many different genes, and the continuous variation observed often has a relatively large environmental component. Horn length in Texas Longhorns is an example of a quantitative trait. This article discusses the basics of selection for quantitative traits, using horn length as an example. Most traits of interest in Texas Longhorns are controlled by many different genetic loci, and many of these traits are also influenced by the environment in which the animal was raised and now lives. These traits typically are expressed along a continuum, rather than as a series of discrete states. For instance, the amount of milk produced by a cow clearly is influenced by her genetics, but it is also influenced by environmental factors (such as how much and what kind of food is available to the cow). Moreover, cows vary along a continuum in how much milk they produce. Such traits are called quantitative traits. Texas Longhorn cattle

  10. Other trait : the tail thickness of Fat Tailed Sheep (Domba Ekor Gemuk) is quantitative trait, so h2of this trait can be measured. Homework : Search some kinds of quantitative traits on internet, textbooks or journal See you next week Wassalam

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