Genetics Report PDF

Selection and Breeding Systems GROUP 4  Animal It aims to improve the genetic makeup of Breeding livestock populations to enhance productivity, disease resistance, and overall quality. It is heavily reliant on selection and breeding systems...

Selection and Breeding Systems GROUP 4  Animal It aims to improve the genetic makeup of Breeding livestock populations to enhance productivity, disease resistance, and overall quality. It is heavily reliant on selection and breeding systems. It is heavily reliant on selection and breeding systems  Selection The process of choosing which individuals will become parents and contribute their genes to the next generation. Selection Methods Individual Selection focuses on the individual animal's performance for specific traits most effective for traits with high heritability Family Selection considers the average performance of a family and selects entire families based on their overall merit useful for traits with low heritability Selection Methods Pedigree Selection method of choosing breeding animals based on the performance of their ancestors. Progeny Testing evaluates the breeding value of an individual based on the performance of its offspring particularly valuable for traits that are expressed only after slaughter or for sex- limited traits Breeding Systems Involve the mating of animals to achieve specific genetic outcomes Breeding Systems OUTBREEDING Involves mating animals that are not closely related. Outcrossing Crossbreeding Involves mating animals Involves mating animals that are not closely from different breeds to related, but within the exploit heterosis, also same breed known as hybrid vigor Breeding Systems Inbreeding Species Hybridization involves mating closely process where two related animals. different species increases the interbreed, resulting in homozygosity of the offspring known as hybrids population can lead to the creation of leads to inbreeding new traits, adaptations, and depression even new species Genetic Control of Farm Animal Traits and Inherited Disorders  Genetic Control of Farm Animal Traits PHENOTYPIC TRAITS Qualitative Quantitative Quantitative Classical Mendalian traits that Features that are measurable are under genetic control with and economically important. little to no environmental modifications. Animal-produced milk Meat Form and structures Eggs Antigens Height and weight Antibodies Skin pigmentation.  Management and Control of Inherited Diseases Genetic Early Diagnosis Medical Regular Screening and and Management Monitoring Breeding Identification of and Disease and Health Management At-Risk Animals Control Tracking Screening Health Vaccination Routine Monitoring and Health Selective Medication Checks Breeding Management of Carrier Record Animals Keeping Inherited Disorders in Farm Animals Widespread use of artificial insemination (AI) and international trading of semen and breeding accelerates the spread of undesirable genes in the population. However, the most common inheritance pattern of genetic diseases is autosomal recessive inheritance. Autosomal An individual must inherit two copies of the Recessive defective gene (one from each parent) to express Inheritance the disorder. Bovine Brachyspina Syndrome (BBS) It is a genetic disorder in cattle, particularly affecting Holstein cows. It is characterized by a shortening of the spine (brachyspina), leading to many developmental abnormalities and usually results in stillbirth or death shortly after birth. Autosomal An individual must inherit two copies of the Recessive defective gene (one from each parent) to express Inheritance the disorder. Bovine Leukocyte Adhesion Deficiency (BLAD) It’s in Holstein cattle is an autosomal recessive congenital disease characterized by recurrent bacterial infections, delayed wound healing and stunted growth, and is also associated with persistent marked neutrophilia. Autosomal An individual must inherit two copies of the Recessive defective gene (one from each parent) to express Inheritance the disorder. Porcine Stress Syndrome (PSS) It is characterized by acute death induced by natural stressors. It is an inherited, autosomal recessive disorder due to a defective ryanodine receptor leading to huge calcium influx, muscle contracture and increase in metabolism. Control of single gene and multifactorial disorders by Selection and Breeding  Single Gene (Mendelian) Disorders Single gene disorders arise from mutations in a single gene. These mutations can follow three common inheritance patterns.  Common Inheritance Patterns Autosomal Dominant Autosomal Recessive X-linked A mutation in one Both copies of the Disorders linked to copy of the gene is gene must be mutations on the X enough to cause the mutated for the chromosome (e.g., disorder (e.g., disorder to appear Hemophilia) typically Huntington's Disease (e.g., Cystic Fbrosis). affect males more severely, as they have only one X chromosome Breeding and Selection for Single-Gene Disorders In breeding programs, controlling single-gene disorders is more straightforward due to the clear inheritance patterns. Genetic testing allows breeders to: 1. Identify carriers 2. Avoid effected individuals 3. Use genetic testing as a preventative tool  Multifactorial Disorders Unlike single-gene disorders, multifactorial disorders are influenced by multiple genes and environmental factors.  Multifactorial Disorders Several genes, each with a small effect, Multiple genes contribute to the risk of the disorder (e.g., diabetes, heart disease, and cleft palate). Environmental factors such as diet, Environmental Factors stress, exposure to toxins, and lifestyle choices can exacerbate or mitigate the risk posed by the genetic predisposition.  Breeding and Selection for Multifactorial Disorders Genetic Predesposition Breeders aim to reduce the genetic risk by selecting individuals with fewer risk alleles for the disorder. Phenotypic Selection In the absence of clear genetic markers for all contributing genes, breeders often rely on selecting individuals based on observable traits or health outcomes. Environmental Management Breeders must also focus on managing the conditions under which animals are raised. Non-genetic (Environmental Control of Inherited Disorders)  Environmental Factors Environmental factors can influence whether a genetically predisposed condition manifests. These include nutrition, housing conditions, and management practices. 1. Nutrition A well-balanced diet is vital for optimal growth and health. Nutrition can keep dormant genetic disorders from becoming active. For example, poor nutrition can lead to the expression of genetic disorders that might remain dormant in a well-nourished animal. Goiter (poultry) Milk Fever (dairy cows) White Muscle Disease (sheep) 2. Management Practices Stress can worsen genetic predispositions. It can lower an animal's immune response, making it more likely to show symptoms of inherited conditions VS Gastric Ulceration (growing-finishing pigs) Practical Solutions Ensuring pigs have enough room to move Gentle and consistent handling during transport or routine checks Gradual dietary changes prevent the gut from being overwhelmed Good ventilation and maintaining the correct temperature in barns Housing Conditions in Poultry Poultry with a genetic predisposition to weak respiratory systems can easily develop these diseases when kept in poor housing conditions. High stocking densities Poor ventilation Build-up of ammonia, dust Stress and moisture Increase spread of respiratory pathogens Weak immune system Housing Conditions in Poultry Infectious Bronchitis Chronic Respiratory Disease Practical Solutions Give birds more space Provide proper airflow Regular cleaning and disinfection Predicting animal mating results and Selection of phenotypes  It was first proposed by the geneticist Angus John Bateman in 1948 through his study on fruit flies Bateman's (Drosophila melanogaster). Principle Bateman's principle is a theory in evolutionary biology that explains differences in reproductive strategies and mating behaviors between males and females in many species  Difference in Reproductive Investment Females typically invest more in reproduction compared to males. Males have relatively low investment in terms of producing sperm, which is inexpensive energetically compared to eggs. Types of Mating Systems In Sexual Animals  Types of Mating Systems In Sexual Animals A. Monogamy The pairing of a single male with a single female. Theoretically, individuals in monogamous pairs will both contribute to the defense and parental care of offspring.  Types of Mating Systems In Sexual Animals B. Polygamy Pairing to more than one mate during a breeding season. 1. Promiscuity When both males and females have multiple mates. 2. Polygyny When's males mate with more than one female. a. Resource Defense Males compete for possession of resource. b. Male Dominance Males establish dominance hierarchy. c. Harems Defended group of females associated with one male d. Lek Male defend small mating territory with no resources.  Types of Mating Systems In Sexual Animals C. Polyandry A group with one female and many males 1. Cooperative All males in the group copulate with the female and all participate in brood provisioning. D. Polygynandry Multiple females and males mate with each other, and males may care for the broods of several females.  Selection of Phenotypes Phenotype is defined as the observable traits or characteristics of an organism which is the result of the interaction of genes and environmental factors. These traits include physical appearances and any other traits that we can observe.  Phenotypic Selection Phenotypic selection occurs when individuals with different characteristics differ in their survival, fecundity, or mating success. Selection is the nonrandom differential survival or reproduction of phenotypically different individuals.  Types of Selection Natural selection drives adaptive evolution by selecting for and increasing the Stabilizing Selection occurrence of beneficial Directional Selection traits in a population. Diversifying Selection  Stabilizing Selection If natural selection favors an average phenotype by selecting against extreme variation, the population will undergo stabilizing selection. Directional Selection When the environment changes, populations will often undergo directional selection, which selects for phenotypes at one end of the spectrum of existing variation.  Diversifying Selection Sometimes natural selection can select for two or more distinct phenotypes that each have their advantages. In these cases, the intermediate phenotypes are often less fit than their extreme counterparts. Thank You! GROUP 4