Paper I — Q4
(a) Differentiate between the following: (i) Endocrine and Exocrine glands. (4 marks) (ii) Phytobiotics and Xenobiotics. (4…
Differentiate between the following: Endocrine and Exocrine glands. 4 marks
Phytobiotics and Xenobiotics. 4 marks
Heart sound and heart beat. 4 marks
Normal and abnormal constituents of urine. 4 marks
Pre-natal and post-natal growth. 4 marks
Describe in detail about preparation of silage along with its advantages and disadvantages. 15 marks
Define essential, critical and limiting amino acids. Enlist the factors affecting amino acids requirement in poultry. (5+10 marks)
हिंदी में प्रश्न पढ़ें
निम्नलिखित के बीच विभेदन कीजिये : अन्तःस्रावी एवं बाह्यस्रावी ग्रन्थियाँ । (4 अंक)
पादपजीवी एवं जीनोबायोटिक्स । (4 अंक)
हृदयध्वनि एवं हृदय धड़कन । (4 अंक)
मूत्र के सामान्य व असामान्य घटक । (4 अंक)
प्रसवपूर्व व प्रसवोत्तर विकास । (4 अंक)
साइलेज बनाने की विधि को उसके फायदे और नुकसान सहित विस्तार से वर्णन कीजिये । (15 अंक)
अनिवार्य, क्रांतिक (महत्वपूर्ण) एवं सीमित अमीनो अम्ल को परिभाषित कीजिये । पक्षियों में अमीनो अम्ल की आवश्यकता को प्रभावित करने वाले कारकों को सूचीबद्ध कीजिये । (5+10 अंक)
Model answer
Drafted with AI by UPSC Answer Check against this question's marking rubric, to the expected length. UPSC does not publish answers for Mains — this is one way to score well, not an official key. How we build rubrics and answers.
(a) Differentiations (i) Endocrine vs exocrine glands: endocrine glands are ductless and release hormones directly into blood to act on distant target organs (pituitary, thyroid, adrenal, endocrine pancreas). Exocrine glands release enzymes, mucus or sweat through ducts onto a surface or lumen (salivary, sweat, mammary, exocrine pancreas).
(ii) Phytobiotics vs xenobiotics: phytobiotics are plant-derived bioactive compounds (essential oils, tannins, saponins, flavonoids) added to feed to improve gut health, immunity and growth. Xenobiotics are foreign chemicals such as pesticides, heavy metals, mycotoxins and drugs, which the liver detoxifies through cytochrome P450 and conjugation, adding metabolic burden.
(iii) Heart sound vs heart beat: heart sounds are audible vibrations from valve closure and blood turbulence, heard on auscultation: S1 ("lub") from atrioventricular valve closure and S2 ("dub") from semilunar valve closure. Heart beat is the cardiac contraction-relaxation cycle started by the SA node, felt as the apex beat or pulse and counted as a rate per minute.
(iv) Normal vs abnormal urine constituents: normal ones are water, urea, uric acid, creatinine, hippuric acid (herbivores) and electrolytes (Na⁺, K⁺, Cl⁻, phosphate, sulphate). Abnormal ones indicate disease: glucose (diabetes), protein (renal damage), ketone bodies (ketosis), blood or haemoglobin, bile pigments (liver disease) and casts.
(v) Pre-natal vs post-natal growth: pre-natal growth runs from conception to birth, first by rapid cell multiplication (hyperplasia) and organogenesis, depending on maternal nutrition and uterine capacity. Post-natal growth runs from birth to maturity, mainly by cell enlargement (hypertrophy), with muscle and fat deposition, depending on nutrition and environment.
(b) Silage: Preparation, Advantages and Disadvantages Silage is green fodder preserved by anaerobic lactic acid fermentation.
Preparation:
- Crop: maize, sorghum or bajra, rich in soluble sugars, cut at the milk-to-dough stage with 30–35% dry matter. Wilt very wet crops.
- Chop to 1–3 cm to release sugar and allow close packing.
- Fill quickly into a pit, trench, bunker, tower or silage bag, compacting hard to expel air.
- Seal with airtight plastic and weigh it down. Lactic acid bacteria such as Lactobacillus plantarum lower pH to 3.8–4.2, suppressing clostridia and spoilage organisms. Allow about 45–60 days before opening.
- Low-sugar crops such as legumes need molasses or additives.
Advantages: green feed through lean and drought months, high retention of carotene, protein and energy, palatable and succulent, little field loss and weather risk, and compact storage.
Disadvantages: costly silos and labour, seepage and aerobic spoilage if sealing is poor, butyric acid or Listeria and mould toxin problems if fermentation fails, and unsuitability of low-sugar crops without additives.
(c) Amino Acids in Poultry Definitions: essential amino acids cannot be synthesised by the bird, or not fast enough, so the diet must supply them (lysine, methionine, threonine, tryptophan, valine, arginine). Critical amino acids are those essential ones most likely to be deficient in practical diets (methionine, lysine, threonine in maize-soybean rations). The limiting amino acid is the one furthest below requirement, which stops the use of all others; methionine is first limiting in maize-soybean diets, and lysine follows.
Factors affecting requirement:
- Genotype: fast-growing broilers need more than layers or indigenous birds.
- Age and stage: requirement per unit feed falls from starter to finisher.
- Production: growth, egg mass, or feathering.
- Energy density: birds eat for energy, so amino-acid density must rise with ME.
- Temperature: heat stress cuts intake, so higher concentration is needed.
- Disease: coccidiosis and enteric infection raise threonine and sulphur amino acid needs.
- Digestibility and anti-nutrients (trypsin inhibitors), and antagonisms such as lysine-arginine.
- Sex and body weight.
How this answer will be evaluated
What earns full marks: Precise definitions, clear differentiation, and comprehensive process description with specific examples.
Evaluation rubric
Each sub-part is marked on its own, against the marks and word limit printed on the paper.
- (a)(i) Distinguish endocrine and exocrine glands by secretion mode and duct presence. 4 marks
compare— paired headings or point-wise contrast → key differences → significance → conclusion
Must cover
- Endocrine: ductless, secretes into blood
- Exocrine: ducted, secretes to surface
- Examples: Pituitary vs Salivary/Sweat
- Hormonal vs enzymatic function
Loses marks
- Confusing ductless with ducted
- Failing to mention blood vs surface secretion
Earns more
- Mention of specific hormones (e.g., insulin)
- Mention of specific enzymes (e.g., amylase)
Extra mark
- Reference to specific livestock pathology (e.g., diabetes)
- (a)(ii) Differentiate phytobiotics (plant-based) and xenobiotics (foreign) compounds. 4 marks
compare— paired headings or point-wise contrast → key differences → significance → conclusion
Must cover
- Phytobiotics: natural plant metabolites
- Xenobiotics: foreign/synthetic substances
- Examples: Saponins vs Pesticides
- Function: gut-health feed additive vs toxic load needing detoxification
Loses marks
- Defining phytobiotics as synthetic
- Confusing source of origin
Earns more
- Mention of specific phytobiotics (e.g., tannins)
- Mention of specific xenobiotics (e.g., heavy metals)
Extra mark
- Link to feed safety regulations
- (a)(iii) Distinguish heart sound (auscultation) from heart beat (mechanical contraction). 4 marks
compare— paired headings or point-wise contrast → key differences → significance → conclusion
Must cover
- Heart sound: acoustic (S1, S2)
- Heart beat: the contraction-relaxation cycle, counted as a rate
- Sound caused by valve closure
- Beat is felt by palpation or pulse; sound is heard by auscultation
Loses marks
- Treating them as identical
- Failing to link sound to valve mechanics
Earns more
- Mention of 'Lub-Dub' sounds
- Linking S1 to AV valves
Extra mark
- Reference to auscultation in veterinary practice
- (a)(iv) List normal vs abnormal constituents found in urine. 4 marks
compare— paired headings or point-wise contrast → key differences → significance → conclusion
Must cover
- Normal: Urea, creatinine, electrolytes
- Abnormal: Glucose (glucosuria)
- Abnormal: Protein (proteinuria)
- Abnormal: Blood (hematuria)
Loses marks
- Listing only normal constituents
- Failing to distinguish pathological markers
Earns more
- Mention of ketones (ketonuria)
- Mention of bilirubin
Extra mark
- Linking specific abnormality to disease (e.g., diabetes)
- (a)(v) Differentiate pre-natal (in-utero) and post-natal (birth) growth. 4 marks
compare— paired headings or point-wise contrast → key differences → significance → conclusion
Must cover
- Pre-natal: Fetal development in uterus
- Post-natal: Growth after birth
- Pre-natal: Organogenesis and cell division
- Post-natal: Muscle/fat deposition
Loses marks
- Confusing embryonic with fetal stages
- Failing to define the birth boundary
Earns more
- Mention of gestation period
- Mention of weaning
Extra mark
- Reference to specific gestation length in livestock
- (b) Detail silage preparation process, listing its advantages and disadvantages. 15 marks
describe— define → structure or process in order → labelled diagram → significance
Must cover
- Process: Chopping, packing, sealing (anaerobic)
- Fermentation: Lactic acid bacteria role
- Advantages: Nutrient retention, year-round feed
- Disadvantages: Spoilage risk, labor intensive
Loses marks
- Omitting the anaerobic requirement
- Failing to list both pros and cons
Earns more
- Mention of pH target (<4.2)
- Mention of specific crops (maize, sorghum)
Extra mark
- Reference to specific silo types (tower, bunker)
- (c) Define essential, critical, and limiting amino acids; list factors affecting poultry requirements. 15 marks
define— precise definition → the distinguishing feature → one example
Must cover
- Essential: Cannot be synthesized (e.g., Lysine)
- Limiting: First to run out in diet
- Critical: essential amino acids most likely to be deficient in practical diets
- Factors: Age, production stage, genetics
Loses marks
- Confusing essential with non-essential
- Failing to list at least 3 factors
Earns more
- Mention of Methionine/Cystine relationship
- Mention of body weight
Extra mark
- Reference to NRC (National Research Council) standards
What "Describe" is asking you to do
Give a full, ordered account of the thing named — its parts, stages or mechanism — in the sequence in which it actually exists or occurs. Most describe questions come from the science optionals, where the marks sit in correct technical detail and, where the stem says so, a labelled diagram.
Structure that answers it
One-line identification of the subject → the parts or stages in their real order, each with its defining detail → labelled diagram where the subject is structural → closing line on function or significance
Where marks are lost
Loose general prose where the examiner is ticking named parts, correct terminology and their sequence; and in the General Studies papers, turning to evaluation before the description is finished.
Practice this exact question
Write your answer and it is marked point by point against the model answer above — what you covered, what you missed, what you got wrong.
Evaluate my answer →More from Animal Husbandry & Veterinary Science 2021 Paper I
- Q1 Answer the following questions in about 150 words each: (a) Write composition of egg yolk…
- Q2 (a) Write about the feeding of swine for lean meat production and its importance in human…
- Q3 (a) Describe causes of different types of anoestrus in dairy cows and suggest their remed…
- Q4 (a) Differentiate between the following: (i) Endocrine and Exocrine glands. (4 marks) (ii…
- Q5 Answer the following questions in about 150 words each: (a) Mention the pattern of crop-r…
- Q6 (a) Describe molecular marker. Write in detail about different types of DNA markers along…
- Q7 (a) Describe the procedure for calculating the economics of milk production in commercial…