Civil Service Examination - Questions and Answers | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Q1: Write chart notes on the following in about 200 words.
Heterosis
Ans: 

• Hybrid vigor, also known as heterosis, refers to the superiority of a crossbreed over its individual parents. This superiority can manifest in various aspects such as size, growth rate, early sexual maturity, and increased resistance to diseases. It occurs in the first generation of crossbreeds from two distinctly different parent breeds. Hybrid vigor is an indication of heterozygosity, and the level of heterosis is linked to the proportion of heterozygous genes. Animals demonstrating significant heterosis are highly heterozygous and cannot reproduce true to their traits.
• To achieve hybrid vigor, each new generation must be produced by crossing parents from two unrelated inbred lines that are heterozygous for multiple genes. The phenomenon is specific to crosses between particular inbred lines, requiring testing of various lines to identify the optimal parental pairing. Despite being highly heterozygous, members of a cross between two inbred lines are genetically identical, ensuring genetic homogeneity and allowing for precise husbandry conditions to maximize production efficiency for that genotype.
• Heterosis is attributed to the entire genome rather than individual genes, and recent evidence suggests that its origins are more related to optimal interactions between gene products rather than the direct expression of heterozygous genes. If the offspring resulting from the interbreeding of the first cross exhibiting hybrid vigor are further interbred, the subsequent generations may not display the same level of vigor.
• The explanation for hybrid vigor lies in the assumption that the mating process brings together a fortuitous combination of complementary or supplementary factors, determining highly valued characteristics.

Q2: Rapid upgradation of livestock in the country is a priority. Detail plan keeping in view the local, regional and socio-economic requirements to achieve shia aim insorporating the new technology available.
Ans: 

• The livestock productivity in our country has significantly improved in recent years, leading to an increased availability of milk and other livestock products per capita. However, this progress is overshadowed by the rising human population, making it challenging to meet the optimal demand for milk, meat, and eggs. It is crucial to swiftly upgrade our livestock to fulfill the population's needs. Given the diverse agroclimatic and socioeconomic conditions in our large country, a uniform policy or method is impractical. Different approaches are necessary for cattle development, considering regional variations.
• In India, as an agricultural country, work animals like cattle (oxen and buffaloes) play a vital role, especially in rural areas where agricultural mechanization is limited. Preservation and improvement of dual-purpose breeds like Kangayan in South India and Marwari in North India are essential for meeting work requirements in agriculture and transportation. Selective breeding, rather than cross-breeding, is recommended to maintain the specific traits suited to local agroclimatic conditions. In terms of milch animals, selective breeding is also advised for breeds like Sindhi, Sahiwal, and Tharparker, while crossing with exotic breeds like Holstein-Friesian, Jersey, and Brown Swiss can further enhance productivity.
• Buffaloes contribute significantly to milk production, and efforts should be directed towards improving indigenous breeds like Murrah and Surti through selection and breeding. Nondescript cattle can be utilized using biotechnological methods like embryo transfer, with males castrated for work purposes. In sheep development, selective breeding is preferred for mutton breeds, while woolly breeds like Nilagiri can be upgraded through crossing with exotic breeds like Merino. Similarly, in goat development, selective breeding of regional breeds is emphasized, with limited crossbreeding with exotic breeds.
• Pork production can contribute to meat production, but aversions to local pig habits can be overcome by proper housing and rearing of exotic breeds like Yorkshire and Berkshire. Poultry farming, a significant source of animal protein, has transitioned from indigenous to exotic breeds. Breeding efforts are focused on further improving egg and meat yields, including the common practice of broiler production.
• In summary, the plan involves rapidly upgrading livestock and poultry in India to meet the increasing demands for meat, milk, and eggs. Differentiated strategies are necessary based on regional and species-specific considerations.

Q3: Describe the effects of inbreeding. What is the usefulness of inbreeding and the reasons for it being practiced for livestock improvement programmes? How the intensity of the inbreeding could be measured?
Ans: 

• In the past, there was a belief that inbreeding caused detrimental effects, but it is now understood that inbreeding itself is not the cause; rather, it reveals latent tendencies, whether positive or negative. The effects of inbreeding on growth rate, reproduction, and vigor are as follows:
  • Growth Rate: Inbreeding tends to depress the growth rate in farm animals, although certain laboratory animals may be less affected. The significant reduction in growth rate discourages the use of inbreeding in commercial herds.
  • Reproductive Performance: Inbreeding experiments, with few exceptions, have shown a reduction in reproductive efficiency. Slow testicular development, delayed puberty, a decrease in the number of eggs shed by females, and increased embryonic death rates contribute to this decline.
  • Vigor: Inbreeding often diminishes vitality, leading to increased death rates in inbred lines. Inbred animals are more susceptible to adverse environmental conditions compared to non-inbred ones.
  • Hereditary Lethals or Abnormalities: In many inbreeding experiments, hereditary lethal genes have appeared, typically recessive in inheritance. These genes, previously hidden in low frequencies in heterozygous states, become exposed in inbreeding.
• Despite these effects, inbreeding can be strategically used in livestock improvement programs:
  • Seed Stock Production: Inbreeding can produce seed stock that serves as parents for outbred or crossbred commercial animals, especially in poultry.
• Reasons for practicing inbreeding include:
  • Genetic Purity and Prepotency: To promote genetic purity and increase prepotency.
  • Identification of Undesirable Traits: To bring undesirable recessive traits to light for removal.
  • Development of Inbred Lines: To develop inbred lines for specific traits.
  • Regrouping Genetic Material: For regrouping genetic material in a controlled manner.
• Measuring the intensity of inbreeding is done through the coefficient of inbreeding proposed by Wright in 1921. This coefficient ranges from 0 to 1 (or 0% to 100%) and represents the probable increase in homozygosity resulting from mating closely related individuals. The intensity is relative to a particular breed or population at a specified time. As the coefficient increases, the proportion of heterozygotes declines proportionately.
• The increase in homozygosity indicated by the coefficient is the expected average result. However, due to chance, individuals with the same coefficient may not necessarily be homozygous for the same loci. The standard deviation for the computed value of the coefficient is affected by the effective number of independently segregating loci in the population.

Q4:  Selection is considered the keystone of the arch of animal improvement. Discuss the process adopted for selecting more than one trait in a breeding programme. Describe the effect of environment on selection process.
Ans: 

• The selection index method, originating from the work of Smith and Hazel, is employed in breeding programs to simultaneously consider multiple traits. This method utilizes scores or index values for each individual, aiming to closely correlate these values with the individual's composite breeding value through a linear combination of traits.
• The necessity for an index arises due to several factors:
  • Unequal Economic Importance: Not all traits considered in breeding programs hold equal economic significance. Differential weighting is required based on the expected economic return from improving each trait.
  • Differing Heritability: Traits do not have the same heritability, and therefore, the same intensity of selection does not yield a proportionate improvement for each trait.
  • Phenotypic and Genetic Interrelationships: Phenotypic and genetic interrelationships exist among traits, and emphasis on one trait may impact changes in another, necessitating consideration of these interrelationships.
• Key information required for developing a selection index includes:
  • Relative Economic Importance: Understanding the economic importance of changes in each trait.
  • Heritability and Variance: Knowing the heritability and genetic and phenotypic variances for each trait.
  • Covariances: Understanding phenotypic and genetic covariances among traits.
• The computation of the selection index involves multiple regression techniques and is represented as a linear combination of phenotypic values for different traits with corresponding weights. This approach allows a clear focus on important parameters when dealing with multiple traits possessing considerable additive genetic variance.
• However, limitations of this method include:
  • Unclear Selection Goals: Breeders may struggle to qualitatively define the goal of selection.
  • Varied Economic Importance: The economic importance of traits can vary across different enterprises.
  • Population-Specific Challenges: Heritability values and genetic and phenotypic interrelationships differ among populations, making it challenging to recommend generalized selection indices.
• Another method, the total score method, closely resembles the selection index method. It lists characteristics based on net phenotypic efficiency or profitability, assigning maximum scores to each based on their relative importance, heritability, and genetic correlation.
• The concept of genotype and environmental interaction emphasizes that the best genotype in one environment may not excel in another. This is crucial in breed improvement, where consideration must be given to how improvements made in one environment carry over to others. Genetic correlations between environments, heritability values, and the physiological differences in characters measured under different conditions help address these challenges.
• Studies on genotype-environment interactions in swine and mice highlight the impact of environmental conditions on the effectiveness of selection. Generally, adaptation tends to be fairly general for most traits, but genetic differences are more fully expressed under favorable environments. Therefore, the evidence supports the desirability of selecting under conditions reasonably similar to those of commercial animals in the specific area.

Q5: Write short notes on: Significance of pedigree selection.
Ans: 

• Pedigree and Selection: Pedigree serves as a record of ancestors, with its biological significance lying in the fact that individuals inherit half of their genetic material from each parent. This information is valuable for predicting the genetic value of offspring, especially when selection on individual traits is challenging due to factors like low heritability, absence of records, or when animals are still immature. However, limitations exist, such as uncertainty about the genetic makeup of parents due to complications like dominance and epistasis. Pedigree selection can be enhanced by providing comprehensive information about both positive and negative aspects of ancestors, including collateral relatives.
• Population versus Individual: A population comprises individuals with common characteristics that group them together. This grouping can be based on species, such as populations of cows, sheep, or fowls, sharing common traits. Populations are inherently heterozygous, and their size, denoted by the number of breeding individuals, varies over time. Population size undergoes changes influenced by factors like births, deaths, and environmental conditions. In contrast, an individual is a single entity compared to others of the same type that collectively form a population. The distinction between a large and small population is arbitrary and varies among species. The rate of change in population size depends on factors like the generation interval and reproductive characteristics, with shorter intervals and larger litters resulting in more significant population growth.

Q6: What is Variance? Discuss the sources of variance. How do the different components of variance affect our choies of breeding and selection methods?
Ans: 

• Variance: Variance is a measure of the degree of dispersion or variation within a population, expressing the average squared deviation of individual measures from the population mean. While average deviation and range offer insights into variability, variance, specifically the average squared deviation, is considered the most useful measure for studying population variability. The study of variation in metric characters, particularly their genetic basis, involves partitioning into components attributed to various causes, with variance being a crucial metric.
• Sources of Variation: The genetics of a metric character involves understanding its variation, which is measured and expressed as variance. This partitioning into genotypic and environmental components, such as genotypic variance and environmental variance, forms the basis of studying heredity versus environment. The phenotypic variance (Vp) is the sum of genotypic (Vg) and environmental (Ve) variances, where Vg is further divided into additive (Va), dominance (Vd), and interaction (Vi) variances.
• Genetic Components of Variance: Understanding genetic properties requires a finer division of phenotypic variance into components like breeding value, dominance deviation, and interaction deviation. The additive variance (Va), representing the variance of breeding values, is particularly significant, as it is a key determinant of resemblance between relatives and the population's response to selection. The partitioning of genetic variance, especially additive genetic versus non-additive genetic and environmental variance, is expressed as heritability, denoted by the Vg/Vp ratio.
• Environmental Variance: Environmental variance encompasses variations of non-genetic origin, influenced by factors like nutrition, climate, and maternal effects. While environmental factors are partly under experimental control, some variations are intangible and cannot be eliminated. Intangible variations may arise from unknown environmental circumstances or developmental variations, introducing complexity to the study of variance.
• Heritability: The value of heritability estimates lies in their ability to inform about the potential progress achievable through selection for a specific trait. A high heritability indicates a strong correlation between genotype and phenotype, suggesting that selection based on phenotype would be effective. Conversely, a low heritability suggests a weaker correlation, requiring more attention to collateral relatives and progeny for successful selection. Heritability values vary among traits, influencing the choice of breeding and selection methods.
• Conclusion: Understanding the sources and components of variance, both genetic and environmental, is crucial for comprehending the heritability of traits. The value of heritability estimates guides breeding practices, indicating the potential success of selection efforts for specific characteristics in a population. However, the heritability of traits depends on various factors, including gene frequencies and the historical context of the population.

Q7: Name and describe indigenous breeds of sheep with reference to wool and mutton production. Nirme two exotic breeds. Suggest a suitable breeding programme using exotio breed(a) for wool production.
Ans: Indigenous Sheep Breeds in Different Regions of India:

• India boasts diverse indigenous mutton and woolly sheep breeds, each exhibiting distinct characteristics in terms of wool quality and quantity. The variation in wool production is especially prominent among different breeds, with some being more woolly than others. The breeds can be categorized based on the climatic zones they inhabit.

Temperate Himalayan Region:

• Gaddi (Bhadarwahis): Originating in Bhaderwah tehsil, Jammu, Gaddi sheep are small yet sturdy, open-grazing throughout the year. They produce fine, lustrous wool, mostly white with colored faces. The wool is suitable for combing and spinning into soft, uniform threads, with a staple length of up to 12 cm. They are clipped three times a year.
• Bhakarwal: Migratory and excellent climbers, Bhakarwal sheep have coarse, colored wool, and their wool yield ranges from 15 to 25 kg. Rams are horned, and ewes are hornless.
• Gurez: Originating in north Kashmir, Gurez sheep have wool without kemp, and ewes are good milkers. The breed shows variations in horned and hornless individuals.

Dry Western Region:

• Chokla: Widely seen in Rajasthan, Chokla sheep have a square and compact frame, and their wool quality ranges from 54 to 60. Rams weigh 32-38 kg, and ewes 22-30 kg.
• Magra: Found in Bihar, Chur, and Nagaur districts of Rajasthan, Magra sheep have a medium-sized frame and light pink skin. Rams weigh 32-36 kg, and ewes 25-30 kg, producing wool with a quality between 45 to 50.
• Nali: Large-framed with white skin, Nali sheep have wool quality between 44 and 50, with a staple length of 8-13 cm. They are shorn twice a year, yielding 2.3 to 3.5 kg of wool annually.

Southern Region:

• Deccani: Deccani and Bellary breeds are black with thin necks and narrow chests. They yield 0.7 kg of wool and have a coarse texture.
• Nilgiri: Found in the Nilgiri hills, Nilgiri sheep produce fine wool of 64s quality with a staple length of 6 cm. It's a crossbreed between Coimbatore, Cape Merino, South Down, and Cheviot breeds.

Eastern Region:

• Shahabadi: Seen in Patna and Chota Nagpur, Shahabadi sheep have a coarse wool type, yielding 0.5 to 1 kg per year, with a mixture of wool, hair, and kemp.

Exotic Breeds and Crossbreeding Programs:

• Merino and Rambouillet: Merino and Rambouillet are exotic breeds known for fine wool production.
• Breeding Programs: Crossbreeding programs have been initiated to enhance wool quality and quantity. Breeds like Hissardale, Nugini, and Kashmiri Merino are the result of crossbreeding with exotic breeds like Australian Merino. These breeds offer a balance of mutton quality, wool fineness, and resistance to local climatic conditions and diseases.

Conclusion: India's indigenous sheep breeds exhibit a rich diversity in wool characteristics, adapting to various climatic zones. The crossbreeding programs with exotic breeds aim to enhance wool quality and quantity while maintaining other desirable traits, contributing to the sustainable development of the sheep industry in the country.

Q8: Write short notes on the following in about 200 words:
Breed synthesis in India
Ans:

• The need to create a new breed arises when existing ones fail to meet specific requirements. In India, numerous indigenous livestock breeds exist, adapted to local environments but often showing poor performance. Conversely, exotic breeds from temperate climates perform well but struggle in India's unfavorable conditions. To strike a balance between hardiness and performance, crossbreeding of indigenous and exotic breeds is undertaken. This involves combining the hardiness of indigenous breeds with the superior performance of exotic ones. The resulting crossbred animals typically have around 50% or 62.5% exotic inheritance and 50% or 57.5% indigenous inheritance. Once it is observed that these animals thrive under local conditions, the specific combination of exotic and indigenous blood is fixed through inbreeding and selection, leading to the creation of a new synthesized breed.
• In India, the synthesis of livestock breeds has been notably carried out in cattle and sheep. Examples include the Preiswal breed, a 5/8 Friesian and 3/8 Sahiwal cross, developed in ICAR or military dairy farms. The National Dairy Research Institute produced breeds like Karan Fries, a cross between Friesian and Tharparker, and Karan Swiss, a cross between American Brown Swiss and Bahlwal. The synthesis of Sunandini, a breed in Kerala State, involved crossing Zebu with Brown Swiss, Jersey, or Holstein, incorporating varying proportions of exotic and indigenous inheritance.
• Historically, breeds like Taylor were synthesized in Patna, Bihar, as far back as 1856, using crossbreeding with shorthorn and channel island bulls with Zebu.
• In the domain of sheep, breeds such as Hissardale, Avikalin, Avivestra, Bharat Merino, and Sandyno have been produced by crossing local sheep breeds with exotic ones, fixing the inheritance through inbreeding. While the Central Sheep and Wool Research Institute produced breeds like Hissardale, Avikalin, Avivestra, and Bharat Merino, the Sheep Breeding Research Institute in the Nilgiris produced Sandyno. The use of exotic breeds like Rambouillet and Merino for crossbreeding with local sheep such as Malpura, Chokle, Nalli, or Nilgiri has resulted in mainly woolly breeds, contributing to both fine wool quality and increased meat yield.