Model Answers for Previous Year Questions | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Q1: Comment on the viability of swine production in India.
Ans:

• The pig stands out as a versatile farm animal, offering diverse management approaches and the ability to be raised and sold at different growth stages. Economically, pigs can be raised with minimal infrastructure costs, benefitting from a short generation interval and large litters, allowing for flexible stock management. A sizable stock provides greater opportunities for selective breeding for fattening or breeding purposes.
• Pigs excel in providing a larger quantity of meat per unit live weight compared to other livestock. Pork, being energy-rich, requires minimal labor in pig husbandry, ensuring quick returns on investment. Pigs efficiently convert garbage, garden waste, and discarded feeds into edible meat, addressing the protein scarcity issue. The potential for a well-organized pig industry holds promise for improving pig production in economically disadvantaged rural areas.
• Despite the cost-effectiveness of high-quality pork compared to mutton, obstacles such as religious restrictions, unhygienic rearing conditions, cultural practices, insufficient capital, technological gaps, and a lack of education among pig farmers impede progress. Additionally, pigs' reliance on grains poses challenges in a country striving for self-sufficiency in food grains.
• However, recognizing the essential role of animal protein in human nutrition, particularly considering that about 30% of protein requirements should come from animal sources, swine production is poised for growth. Pigs can complement mixed farming, crop raising, and other livestock activities, acting as "mortgage lifters" for farmers in developed countries.
• Looking ahead, the limitations of sheep, goats, and cattle in meeting the growing meat demand due to low prolificacy and extended gestation periods make pigs and poultry crucial contributors. In rural areas, pig husbandry often remains at a subsistence level, relying on traditional practices. Transitioning from subsistence to commercial pig production requires addressing environmental, health, and management issues. Simply hybridizing indigenous stock with fast-growing exotic breeds without ensuring proper conditions and management may lead to disastrous outcomes. Exotic pigs, despite favorable growth genes, may not express their full potential in poor environmental conditions, making sound management imperative for success.
• Numerous exotic pig breeds are well-suited to our conditions, offering an opportunity to transition from traditional subsistence pig farming, where local pigs are fed on domestic waste and night soil, to a more commercially viable swine production system. By replacing local pigs with these exotic breeds, swine production can become both aesthetically acceptable and economically feasible in India.

Q2: Write short notes on genetic advances per generation.
Ans:

• Offspring from these bulls would be 3500-3000-1000 kg. The phenotypic improvement observed in one generation is the difference between the average performance of the selected group and the average performance of the entire population they belong to.
• In a herd of 50 cows, where the first lactation yield for 306 days averages $500, let's assume that 30 cows were chosen as breeding stock, and their yield averaged 2,500 kg. The selection differential for these cows is calculated as 2,500 - 1,800 - 1,000 kg for the specific trait.
• Similarly, for the bulls, if three selected bulls averaged 3,500 kg, the selection differential for the offspring from these bulls would be 3,500 - 3,000 - 1,000 kg. This selection differential represents the phenotypic improvement anticipated in the next generation based on the chosen breeding stock.

• This doesn't necessarily mean there will be a 1500 kg increase in milk production per cow in the next generation, as the increase is influenced by both genetic and environmental factors. The proportion of the increase attributed to genetics is determined by the heritability of the trait.
• For instance, if the heritability of the trait, such as milk yield, is 0.30, then the genetic portion of the increase would be 0.3 x 1500 = 450 kg. Therefore, the practical genetic advance per generation for milk yield would be 450 kg.
• It is important to note that the genetic advance per generation, or the effectiveness of the improvement rate through selection, relies on key factors like the accuracy of selection, selection intensity, and the genetic variation or heritability of the trait.

Q3: Explain the foundational principles underlying the modern concept of animal breeding.
Ans:

• Although human understanding of inheritance mechanisms is comprehensive, it does not empower individuals to manipulate these processes to achieve desired outcomes actively. There is no central control over the aggregation of genes to produce gametes with a non-random proportion of desired genes from heterozygous parent gametes. Instead, breeders are limited to selecting animals that best suit their needs and accepting the gametes these animals produce. Even when gametes are generated, breeders cannot selectively choose those with preferred genes or promote the union of similar ones. The only option is to allow the array of gametes from chosen parents to unite randomly with the ova produced by the selected females.
• Breeders cannot alter Mendelian laws, the number of genes, or the linkage relations, nor can they generate new genes. While genes can be transformed to some extent by treatments like X-rays and radium, such procedures often result in high sterility and produce mostly undesirable mutations, providing little practical help to breeders.
• In essence, breeders are left with the choices of parents (selection) and various mating systems (breeding), all subject to the laws of chance. This means breeders have the power to decide which animals will have many, few, or no offspring through selection practices that have been employed for an extended period. Selection can be based on individual performance, ancestry, progeny, or a combination of these factors in varying degrees. As the selected parents will not be identical, breeders can use various methods to determine which chosen males will be mated with selected females.

Q5: Discuss the conditions under which you would expect selection for crossbreed performance to yield better results than intrapopulation selection.
Ans: 

• Before delving into the comparison between selection for crossbreed performance and intrapopulation selection, it's essential to clarify the distinction between the two. Intrapopulation selection occurs within the same breed, differentiating it from inbreeding, where related animals are mated. In intrapopulation selection, animals belong to the same breed or group but are not closely related, eliminating the inbred population aspect. Crossbreeding involves mating animals from distinct breeds, such as pairing a Jersey bull with a Sindhi cow.
• In interbreeding, heterozygosity and variability increase, while prepotency decreases. When using crosses for breeding, their offspring tend to exhibit more variability than the crossed parents and generally have an average merit lower than their purebred counterparts. Opting for selection based on crossbreed performance proves advantageous when seeking enhanced vigor, faster growth rates, increased fertility, and overall robustness. It is also relevant when exploiting the dominance of certain characters and introducing new genes into a closed population.
• When a specific breed lacks certain traits, the quickest and most reliable method for improvement is to introduce genes through crossbreeding with stock known to excel in that trait. Initiating new breeds with a broad genetic makeup is another scenario where crossbreeding is favored. Crossbreed performance is preferable for producing market animals, utilizing heterosis, such as in sheep or goats for slaughter or cows for higher milk yield, despite potential reductions in breeding value.
• Strategic crossbreeding, where complementary breeds are judiciously chosen, may result in increased vigor. The success of crossbreeding hinges on whether the production increase outweighs potential confusion about the breeding value of crossbred individuals and the increased cost of replacing purebred stock in a modern crossbreeding system. This approach is more likely to be profitable in species like swine, poultry, and sheep, as opposed to larger livestock such as cattle.
• Selection for crossbreed performance is also recommended when heterosis in crossbred females can be utilized by further crossing with a third, different breed in rotational crossing systems. Moreover, it is likely to yield better results than intrapopulation selection when employing crisscrossing techniques, using heterosis in dams while avoiding the decline in average individual merit that usually occurs in intrapopulation matings.
• Additionally, selection for crossbreed performance is advisable when initiating new breeds or breeding programs with superior performance compared to the foundational purebred stock. Characteristics can be stabilized over a few generations through inbreeding after the initial crossbreeding.

Q6: Define selection. How will you construct selection indices for effecting genetic progress for milk production in cattle?
Ans:

• Selection involves choosing parents for the next generation. By selecting, we determine which individuals will have many offspring, which will have few offspring, or which will have no offspring at all.
• The optimal selection process utilizes all available information about an individual's breeding value, incorporating an index derived from various sources such as the individual itself, its parents, full-siblings, half-siblings, and other relatives. When the character under consideration is limited to one sex, information about unmeasurable individuals comes solely from their relatives. The objective is to amalgamate all relevant information into an index, based on which individuals will be chosen. In improving the economic value of animals or plants, selection typically applies to multiple traits simultaneously, assigning appropriate weights to each trait based on its relative economic importance, heritability, and genetic and phenotypic correlations. The various traits are combined into a score or index, enabling selection as if the index were a single character, leading to the most rapid possible improvement in economic value.
• The selection index represents the best linear prediction of an individual's breeding value and takes the form of multiple regressions of the breeding value using all available sources of information. In a simple scenario where the only information is an individual's phenotypic value as a deviation from the population mean (P), the predicted breeding value (EBV) is calculated as EBV = b(P), where b is the regression of breeding value on phenotypic value. If there are multiple pieces of information (P, P₁, P₂, etc.), where P1 is the phenotypic value of an individual or a group of relatives, these pieces are termed measurements. The index for the individual then becomes I = bP + b₁P₁ + b₂P₂ + ..., constructing a selection index that considers various sources of information.
• When creating a selection index for improving genetic progress in milk production, cows can be ranked based on their milk production. Factors such as early maturation, higher milk production per lactation, high-fat percentage in the milk, optimal lactation length, regular calving, and annual calving are assigned values. These values are then combined to yield a single value for each individual. Information from different types of relatives, including parents, siblings, and half-siblings, is also considered to arrive at a comprehensive selection index.