Lecture 11Outline of previous lectureI. Evaluation of slaughter animalsa. Yield gradeb. Quality gradec. Dressing %II. Factors influencing value of slaughter animalsa. Dressing percentb. Fatnessc. Marblingd. Musclinge. Carcass weigh and ageOutline of current lectureI. Qualitative/QuantitativeII. InbreedingIII. Line breedingIV. OutcrossingV. Cross BreedingVI. FutureLearning objectivesTo understand the differences in line-breeding, in-breeding, and cross-breedingTo understand the election methods used in breeding livestockIn-breed-same breed (clearly relatable/i.e.father daughter)Created more homozygous genesLine breeding-same breed (related down the line)Cross breeding-completely different breedsGenetic problemsSheepSpider geneCattleAngus bulls-curly calfPSSPietrainHorsesHYPPQualitative TraitsThose for which phenotypes can be classified into groups rather than numerically measuredi.e. coat color, horns vs. polledCommonly controlled by a single geneQuantitative TraitsThose that are usually controlled by many genes, having a small effectMost traits that are economically important are quantitatively measuredAdditive in natureMany genes contribute to a measured effectGene ActionSex linked traits-traits genetically controlled by genes located on the sex chromosomesi.e. hemophilia, color blindness, are controlled by a gene on the X chromosomeSex limited traits that are expressed in only one sexi.e. milk production, egg production, and cryptorchidismSelectionDetermining which animals will reproduceNatural selection-mating of animals in a natural environmentArtificial selection-humans dictate breeding of animalscastrationInbreedingMating of relativesMore closely related, the higher the degree of inbreedingCreation of more homozygous genesAnimals are more likely to breed trueOnly allows genes to be expressedAvoided by most producers dues to commonality of genetic defects and an overall decline in vigor and performanceInbreeding depression-loss of reduction of vigor, viability, or production that usually accompanies in breedingInbreeding does not increase problems, it only allows genes to be more expressedCreation of more pairs of homozygous genesTherefore animals are more likely to breed truedoes not increase the number of recessive genes in the population, it merely allows them to be expressedWhere is inbreeding usedCrops: Corn99% all corn produced1 plant (female)=800 or moreAnimals: chickensHen can produce 200-225 chicks/yearSeedstock producersBreeding purity-BB, Bb, bbIntensive inbreedingmating closely related animals for many generationsline breedingmild form where inbreeding is kept lowkeep high genetic relationshipPhenotype effects of inbreedingincreases phenotypic uniformity if accompanied by selectionsuperior genetichigh homozygous and likely to pass oncan result in a depression of traits related to physical fitnessi.e. fertility, viability, and growth rateanimals are less vigorousHigh inbreedingUsually detrimental to reproduce performance, pre-weaning, and post-weaning growth as they are more susceptible to environment stress60-70% of inbreeds show detrimental effects while 30-40% show no effect and posses improved productivityInbreeding in livestock productionCrossing of inbred lines-heterosisGenetic testingQuickly identifies some desirable and undesirable genesEspecially hidden and serious recessive traitsInbred animals with superior performance generally have superior inbreeding value sand uniform progenyHeterosis compensates for inbreeding depressionIndustry with most in breedingDogs-most detrimentalOutcrossingUnrelated animals within the same breed are matedAngus and angus-different genesHereford breeder-good line developed but low in yearling weight will go out and find a bull with high EDP in yearling weight perhaps from another lineCrossbreedingMating to different breedingHybrid vigor-defined as “ the superiority of the crossbred offspring over the average of the pure breeds (parents) used to make the crossThe two primary reasons to crossbreedheterosis and complementary of traits (mix of different traits)preferred system of mating for commercial swine production because more pigs survive from birth to weaning and are heavier at weaningcrossbred sows may wean 40-45% heavier litters than purebreds90% are crossbredTwo basic types of crossbreedingRotationalCombines 2 or more breedsDifferent breed of boar is mated to a replacement crossbred female produced by the previous generationTerminalNone kept for breedingDairy CattleLine breedingPerformance of offspringDHIA-keeps recordsWhat mating systems are used in the horse industry?Line breedingLook at performanceIntelligence is highly heritableAncestorsWhat does the future hold for livestock mating systemsComposite animalsFit environmentSuper efficientSuper productiveIncreased testingPerformanceGeneticANSC 107 1nd EditionLecture 11  Outline of previous lectureI. Evaluation of slaughter animals a. Yield gradeb. Quality grade c. Dressing %II. Factors influencing value of slaughter animalsa. Dressing percent b. Fatnessc. Marbling d. Muscling e. Carcass weigh and age  Outline of current lecture I. Qualitative/QuantitativeII. InbreedingIII. Line breeding IV. OutcrossingV. Cross Breeding VI. Future Learning objectives- To understand the differences in line-breeding, in-breeding, and cross-breeding- To understand the election methods used in breeding livestocko In-breed-same breed (clearly relatable/i.e.father daughter)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Created more homozygous genes - Line breeding-same breed (related down the line) - Cross breeding-completely different breeds- Genetic problems o Sheep Spider geneo Cattle Angus bulls-curly calf o PSS Pietraino Horses  HYPP  Qualitative Traits- Those for which phenotypes can be classified into groups rather than numerically measured o i.e. coat color, horns vs. polled o Commonly controlled by a single gene  Quantitative Traits- Those that are usually controlled by many genes, having a small effect- Most traits that are economically important are quantitatively measured o Additive in nature o Many genes contribute to a measured effect  Gene Action- Sex linked traits-traits genetically controlled by genes located on the sex chromosomes o i.e. hemophilia, color blindness, are controlled by a gene on the X