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

Q1: Write short notes on: Gastrulation
Ans: 

• Following the cleavage phase, there is an extensive movement and reorganization of cells in the blastoderm of the blastula. This transforms the previously single-layered thick embryo (blastula) into a two or three-layered thick embryo known as the Gastrula. The three layers of the gastrula, namely the Ectoderm, Mesoderm, and Endoderm, are considered primary germ layers. These layers serve as the foundational structures from which various organs of the animal body develop.
• The morphogenetic movements during gastrulation collectively bring the germ layers into their respective positions. The outermost layer is called the Ectoderm, the middle one is the Mesoderm, and the innermost layer is the Endoderm. The fully formed gastrula features a central cavity known as the Archenteron, lined by the endoderm, and it communicates with the exterior through an opening called the Blastopore. In later developmental stages, the Archenteron becomes the cavity of the alimentary canal, while the blastopore develops into either the mouth (in protostomia) or the anus (in deuterostomia).
• During gastrulation, there is a decrease in the rate of cell division, and the first evidence of gene transcription (RNA synthesis) becomes apparent. This transcription plays a role in specifying the proteins required for gastrulation. Subsequent transcription during later development dictates proteins characteristic of the differentiated state of cells, such as acetylcholinesterase in nerve cells, myosin in muscle cells, and melanin pigment in epidermal cells.
• Gastrulation is a crucial stage in the embryonic development of multicellular animals, marked by the following events:
  • Rearrangement of blastular cells through morphogenetic movements.
  • Slowing down or inhibition of cellular division.
  • Significant growth.
  • Changes in metabolism, including intensified oxidation rates.
  • Initiation of chemodifferentiation through the synthesis of new and different types of protein molecules.

Q2: Write short notes on: Effect of hot weather on chickens
Ans: 

• Chickens maintain a body temperature ranging from 40.5°C to 43.2°C and struggle to dissipate heat efficiently through radiation when the atmospheric temperature exceeds 37°C. Since birds lack sweat glands, they rely on limited evaporative cooling. Panting becomes the primary method of heat dissipation at high ambient temperatures, with risks of heat prostration and death starting at 38°C.
• Poultry raised in elevated temperatures experience lighter weight at sexual maturity, reduced food consumption, and increased feathering. High temperatures impact egg size and feed consumption during the laying period. The elevated temperature causes a considerable decrease in food intake, leading to insufficient intake of essential proteins, minerals, and vitamins. Failure to adjust the diet proportionally may negatively impact performance.
• Intensive poultry farming demands immediate and special attention, particularly during summer, as heat stress can result in significant losses, causing a nearly complete reduction in egg production. High-yielding birds are particularly vulnerable to elevated temperatures and humidity. The critical temperature for fowls is 47.3°C, and an environmental temperature of 40.5°C with 75% relative humidity raises the body temperature to 48°C, resulting in bird fatality. In contrast, the same temperature with 55% relative humidity produces a non-lethal body temperature of 40°C. At the critical temperature point, observations include reduced egg size and thin-shelled eggs in the flock.
• At 32°C, birds exhibit signs of distress, with increased air gasping. Symptoms become more evident beyond 36°C, with potential losses of up to 50% of the bird population. Disease symptoms under heat stress include panting, reduced feed intake, clustering around water pools, excessive wet droppings, increased daily mortality, soft-shelled eggs, and reduced egg production. Birds affected by heat stroke display gasping, convulsions, and eventually succumb to death.

Q3: Write short notes on: Environmental stress on grazing behaviour
Ans: 

• Environmental stress in livestock primarily refers to climatic stress, although the environment encompasses other factors beyond climate. In cattle, the impact of climatic stress is prominently reflected in their grazing behavior, subsequently influencing their production and reproduction.
• The duration of daytime grazing for cattle varies based on factors such as the degree of climatic stress, the breed and type of cattle, and the quantity and quality of available pasture. In humid tropical climates, high-grade Bos taurus cattle tend to have significantly reduced daylight grazing, mostly limited to early morning and late afternoon periods. 
• The duration of nighttime grazing fluctuates based on the level of climatic stress. Even crossbred Bos taurus x Bos indicus cattle exhibit shorter daytime grazing periods in the tropics compared to temperate climates, seeking shade during the middle of the day. When allowed to graze at night with proper protection against predators, these cattle tend to graze continuously, especially when grass quantity is suboptimal. Limited feed availability increases total grazing time, as does poor grazing quality, leading to more selective behavior in animals.
• Cattle managed under nomadic or semi-nomadic conditions in semi-arid tropics also experience changes in grazing behavior and subsequent impacts on production. During the dry season, decreasing water content in available forage raises the demand for water, coinciding with diminishing surface water resources. As animals have to travel longer distances to obtain adequate feed and water, additional walking increases muscular activity, requiring more feed and generating extra heat. 
• This heat needs dissipation, further depleting the animal's water resources. Simultaneously, the nutrient content of available feed decreases during the progressing dry season. Diminishing water supplies may become highly mineralized, and ambient temperatures may rise, resulting in an additional increase in the animals' water requirements. These factors collectively subject nomadic or semi-nomadic livestock in semi-arid tropics to significant physiological stress, potentially causing a substantial reduction in productivity.

Q4: Write short notes on: Adaptation to thermal stress in animals
Ans: 

• A thermal equilibrium is achieved only when the overall heat gain is counterbalanced by the total heat loss. The cutaneous vasomotor responses to thermal variations are primarily controlled by sympathetic vasoconstrictor nerves. Peripheral vasodilation is induced by inhibiting the sympathetic vasoconstrictor tone. 
• Warmth can reduce vasoconstrictor tone either through an elevation in hypothalamic temperature or reflexively via thermoreceptors in the skin. Local skin vasodilation may also occur due to the direct impact of warmth on blood vessels or the presence of bradykinin, a potent vasodilator released from activated sweat glands in humans.
• Beyond an environmental temperature of approximately 31°C, skin vasodilation ceases to enhance heat dissipation, and unless other mechanisms augment heat loss, an increase in body temperature will occur.
• When the environmental temperature drops, the regulation is achieved by reducing heat loss through physical adjustments. If this proves insufficient, heat production is increased as a secondary defense through chemical regulation.

Q5: Write short notes on: Methods of controlling climatic stress in cattle
Ans: 

• The microclimate, which includes factors like temperature, humidity, air velocity, and thermal radiation, plays a crucial role in the heat balance of animals, directly impacting their production and health. Adverse environmental conditions necessitate the modification of these factors.
• In cold environments, animals experience a net heat loss due to energy exchange. This can be compensated for by increasing feed intake to maintain the heat balance.
• On the other hand, in hot environments, the energy exchange may result in a net heat gain if excess heat cannot be dissipated through the evaporation of moisture from the skin or respiratory tract. The solution is to favorably modify one or more microclimatic factors.
• For cold climates, buildings are insulated to conserve animal heat, and supplemental heat may be added to maintain desirable conditions. Ventilation is controlled to reduce humidity, and proper drainage ensures that free water leaves as a liquid instead of vaporizing at the expense of animal heat. Solar radiation is maximized through appropriate building design and orientation. Outside pens are strategically located to provide protection from cold winds and exposure to solar radiation.
• In hot weather conditions, well-designed shades are implemented to reduce the radiation heat load, and there is an ample supply of cool drinking water near or under the shades. Showers that wet the animal's skin surface enhance evaporative cooling. Air movement is increased through the use of wire or cable fencing, placing pens and corrals on hills, using fans in areas with low movement, and planting low-growing vegetation around pens and corrals. Additional methods include inspired cooling for dairy cows, evaporative cooling, or total barn air-conditioning.

Q6: Write short notes in about 200 words: Sanitary analysis of water
Ans: 

• To assess the suitability of a water supply for domestic use or livestock, a comprehensive water analysis is required. This includes: 
  (i) a topographical examination of the water source,
  (ii) a physical and chemical examination,
  (iii) a bacteriological examination, and
  (iv) a microscopic examination.
• Many farms and pastures rely entirely on surface water sources, and the examination involves identifying potential sources of pollution, such as animal excreta, stable wastes, and carcasses. Contamination of gathering grounds and drainage areas for streams and ponds must also be investigated, particularly polluted surface waters receiving drainage from stables, cowsheds, and cesspools.
• While a topographical survey provides information about the water supply, chemical and bacteriological examinations are crucial to identify toxic impurities and bacterial infections. Sanitary analysis primarily involves the bacteriological examination of water. The authoritative interpretation of results and the hygienic classification of water supplies depend on the following information:
  (i) Bacterial coli serves as a key indicator of recent excretal pollution. Finding this organism in water in more than minimal numbers should not be ignored.
  (ii) The presence of organisms from the IAC group in water, in the absence of fecal coli, may result from
  (a) soil contamination,
  (b) contamination with excretal material at a distance sufficient for fecal coli to die out,
  (c) contamination with excreta from a person discharging IAC in almost pure culture (rare), or
  (d) inadequate treatment of initially polluted water with chlorine, which only killed more susceptible fecal coli.
• In general, the presence of fecal coli indicates recent and potentially hazardous excretal contamination that requires immediate attention. The presence of IAC in untreated water suggests less recent contamination, which, though not immediately dangerous, calls for further steps to achieve better water purity. The presence of IAC in treated water necessitates adequate water treatment.

Q7: Write short notes on: Freezing microtomy
Ans: 

• Before examining body tissues and organs for histopathological changes under a microscope, they need to undergo a series of preparations. This preparation involves fixing, hardening, dehydrating, de-alcoholizing, clearing, embedding, section cutting, mounting, and staining.
• The process of section cutting is performed using a microtome, an instrument that slices tissues into extremely thin sections for microscopic examination. Typically, the material is embedded in a suitable medium like paraffin wax, which usually takes about 18 hours. However, for specific purposes such as identifying fat in tissues, certain impregnation methods for the central nervous system, or the rapid examination of pathological material like tumors that need quick sectioning and staining immediately after removal, frozen sections are prepared. 
• These sections are as thin as 5, and they experience less shrinkage compared to paraffin-embedded material. It's important to note that frozen sections cannot be stored before staining, and they should only be used for the mentioned specific purposes, not as an alternative to paraffin embedding. While frozen sections are manipulated similarly to ordinary sections, extra care is needed due to the absence of an embedding mass. Tissues should not be frozen too hard, as overly frozen sections may shrivel up and split. A specialized microtome is utilized for cutting frozen sections.

Q8:  An animal's productivity is affected, both directly and indirectly by environmental factors.' Discuss the statement with reference to either milk production in cattle or wool growth in sheep. Briefly describe the methods of controlling climatic stress in one of the above species.
Ans: 

• Climate, an uncontrollable environmental factor, holds the greatest influence over animal productivity, with all other factors being largely alterable and mostly influenced by climate. Therefore, the initial discussion focuses on the direct and indirect effects of climate on productivity.
• Direct climate effects on animals involve their attempts to maintain body temperature suitable for optimal biological activity. Domestic animals, as homeotherms, have limited means to vary heat production compared to the methods for heat dissipation. While they can reduce productive processes and muscular heat production, basal heat production remains mostly unaltered to maintain minimal body warmth.
• The direct effects of climate on cattle encompass various aspects, including grazing behavior, feed intake, water intake, efficiency of utilization, loss of nutrients, growth, milk production, and reproduction. Grazing behavior, for instance, varies during the daytime in response to climatic stress, breed, and type of cattle. In humid tropical climates, high-grade Bos taurus cattle exhibit radically curtailed daytime grazing, mostly confined to early morning and evening hours. The length of nighttime grazing fluctuates with the degree of climatic stress. 
• Dry seasons further impact grazing by increasing the demand for water due to decreasing forage water content. This prompts animals to walk longer distances to find adequate feed and water, raising feed and water demand as increased muscular activity requires extra feed and generates additional heat. This heat needs dissipation, further depleting the animals' water resources. Consequently, energy is diverted for dissipation purposes, reducing the energy available for milk production. 
• Additionally, the nutrient content of available feed decreases as the dry season progresses, and diminishing water supplies may become highly mineralized. Rising ambient temperatures further increase the animals' water requirements. These factors collectively subject nomadic or partially nomadic livestock in semi-arid tropics to significant physiological stress, substantially reducing productivity.
• In high ambient temperatures, there is a decrease in feed intake, and in extremely high temperatures, food consumption and rumination essentially stop, adversely affecting milk production. The water intake of animals increases with rising ambient temperatures up to a certain point (85°F or 29.4°C), after which it declines. Humidity also plays a role, with increasing humidity decreasing water consumption. Moreover, elevated ambient temperatures reduce the efficiency of feed utilization.
• Experimental evidence indicates that high ambient temperatures depress milk, butterfat, and solids-not-fat production. In temperate climates, twins exhibit 44 percent higher milk production than their counterparts in the tropics. The optimal temperature for milk production in temperate cattle breeds is around 10°C (50°F), while the critical temperature, after which milk production significantly declines, is 21 to 27°C (70 to 80°F) for Jersey and Holstein, and 29 to 32°C (86 to 90°F) for Brown Swiss and tropical cattle. 
• The butterfat content of milk in temperate climates decreases gradually until the ambient temperature reaches 29°C (85°F) and then rises. This is attributed to the fact that above 29°C (85°F), the decline in milk production is more rapid than the decline in the percentage of butterfat in milk. High ambient temperatures also impact other milk constituents, such as a rise in chloride content and a fall in lactose and total nitrogen content when temperatures exceed 27 to 32°C (80 to 90°F).
• The indirect effects of climate primarily impact the quantity and quality of available feed. Additionally, climate influences the incidence of diseases and parasites, as well as the storage and handling of feed, with variations across different agroclimatic regions. In equatorial and humid tropical regions, forage often has high water content, affecting the total quantity of feed consumed and potentially reducing dry matter intake. The nutritive value of tropical forage is limited by its low crude protein (CP) content, and digestible crude protein (DCP) content is more variable than total digestible nutrients (TDN), resulting in a reduction in milk yield.
• In semi-arid and arid tropics, challenges in nutrition and production stem from the intensely seasonal nature of forage resources and the risk of low nutrient intake and water deprivation during the dry season. High ambient temperatures and humidity create favorable breeding environments for internal and external parasites, fungi, and disease vectors, further impacting milk production.
• Methods for controlling climatic stress involve acclimatization, which can be temporary or permanent, depending on whether the animal increases heat loss, reduces heat production, or enhances tissue tolerance to higher temperatures. Temperate cattle in the tropics are kept in cool conditions through appropriate housing and access to water. Selection of cattle breeds more tolerant to heat is also considered.
• Since various environmental factors, including temperature, humidity, air velocity, thermal radiation, and microclimate, are involved in heat balance, production, and health, modifying these factors in adverse environments is crucial. In hot environments, if excess heat cannot be dissipated through evaporation of moisture from the skin or respiratory tract, it is necessary to alter one or more microclimatic factors favorably.
• For cold climates, buildings are insulated to conserve animal heat, and supplemental heat is provided to maintain desirable conditions. Ventilation is controlled to reduce humidity, and good drainage is ensured to prevent free water from vaporizing at the expense of animal heat. Solar radiation is maximized through proper building design and orientation.
• In hot weather conditions, well-designed sheds are provided to reduce radiation heat load, with food and a sufficient supply of cool drinking water located near or under the shades. Showers that wet the animal's skin surface are used to enhance evaporative cooling. Air movement is increased through wire or cable fencing, fans, and other methods, including inspired cooling for dairy cows, evaporative cooling, or barn air conditioning.

Q9: Write short notes in about 200 words: Animal diseases associated with water supply
Ans: 

• It is widely believed that the transmission of Johne's disease in cattle is primarily through the contamination of water and other ingested substances with infected feces. The ability of the Johne's bacillus to survive outside the animal body for an extended period is closely associated with the spread of the disease through these means. The Johne's bacillus exhibits a significant capacity for survival when infected feces are deposited into water. 
• Consequently, it is important to prevent cattle from entering and contaminating ponds and other water sources. Additionally, other common infections in livestock, such as tuberculosis, bovine contagious abortion, anthrax, blackquarter, swine erysipelas, and parasitic infestations like fascioliasis, parasitic bronchitis, and parasitic gastro-enteritis, may occasionally be transmitted through waterborne routes.

Q10: Write short notes on: Syndesmochorial placenta
Ans: There are two main types of placenta:

• Deciduate: In this type, the foetal part of the placenta is closely associated with the maternal part, and the entire placenta is shed off after parturition. Examples include humans and primates.
• Indeciduate: In this type, the association between the foetal and maternal parts is not as close, and the maternal endometrium is not shed. This type is found in all domestic animals.

Indeciduate placenta can be further classified into three types:

• Cotyledonary: Chorionic villi are grouped into well-defined projections called cotyledons, separated by smooth stretches of chorion. Foetal cotyledons fit into maternal cotyledons, resembling a press button. This type is found in ruminants.
• Diffuse: Chorionic villi are scattered all over the chorion. This type is observed in animals like mares and sows.
• Zonary: Chorionic villi form a band above the middle of the chorionic sac, creating a girdle-like structure. This type is partially deciduous, as the circular ring is shed during parturition. Examples include carnivores.

Placenta also varies in the number and types of cell layers between the mother's blood and the embryo, leading to different classifications:

• Epitheliochorial: Chorion rests on intact uterine epithelium, as seen in pigs.
• Syndesmochorial: Varying amounts of uterine epithelium may be absent, bringing the chorion into contact with the uterus's connective tissue. Cattle, deer, and giraffes have this type of placenta, with areas of attachment called placentomes where foetal cotyledons and maternal caruncles interdigitate.
• Endotheliochorial: No maternal connective tissue intervenes between the endothelium of maternal vessels and the chorionic epithelium. This type is found in dogs.
• Haemochorial: Chorion is bathed in maternal blood, a characteristic of human placenta.
• Haemoendothelial placenta: Foetal vessel endothelium appears to be in direct contact with maternal blood, observed in rabbits.