Animal Nutrition MCQs
1. Hay is best defined as:
A. Fresh green forage fed immediately
B. Fermented high-moisture fodder
C. Dried and preserved forage for scarcity periods
D. Concentrated cereal feed
Correct Answer: C. Dried and preserved forage for scarcity periods
Explanation: Haymaking is the process of turning green forage into a stable, storable feed by reducing its moisture content to a level where microbial activity is inhibited.
2. The ideal color of good quality hay is:
A. Yellowish brown
B. Bleached white
C. Green
D. Dark brown
Correct Answer: C. Green
Explanation: A bright green color indicates that the hay was cured rapidly and harvested at the correct maturity, retaining high levels of carotene (Vitamin A).
3. Moisture content of good quality hay should be less than:
A. 25%
B. 20%
C. 15%
D. 10%
Correct Answer: C. 15%
Explanation: To prevent mold growth and “mow-burn” (spontaneous heating), hay must be dried to about 15% moisture or less before storage.
4. Which hay has the highest crude protein content?
A. Oat hay
B. Berseem hay
C. Lucerne hay
D. Sorghum hay
Correct Answer: C. Lucerne hay
Explanation: Lucerne (Alfalfa) is a legume known as the “Queen of Forages.” Legumes generally contain significantly higher crude protein and minerals compared to grass or cereal hays.
5. A row of cut hay allowed to dry before baling is called:
A. Swath
B. Mow
C. Windrow
D. Bale
Correct Answer: C. Windrow
Explanation: A windrow is a long row of raked hay. It is shaped to allow air circulation for final drying and to make it easy for a baler to pick up.
6. The machine used to improve aroma and color of hay after cutting is:
A. Rake
B. Baler
C. Tedder
D. Harvester
Correct Answer: C. Tedder
Explanation: A tedder lifts and scatters the cut forage. This speeds up the drying (curing) process, preserving the green color and aromatic compounds by reducing the time the crop spends on the ground.
7. Best suited crop for hay making is:
A. Maize
B. Bajra
C. Oat
D. Rice
Correct Answer: C. Oat
Explanation: Oats have thin stems and a high leaf-to-stem ratio, making them much easier to dry uniformly compared to thick-stemmed crops like Maize.*
8. Which structure is considered best for hay drying?
A. Fence rack
B. Tetrapod
C. Hay rack
D. Tripod
Correct Answer: D. Tripod
Explanation: In humid regions, hay is often dried on structures. The tripod is considered superior because it keeps the hay off the ground and allows air to flow through the center of the stack.
9. Drying agents in hay making act by:
A. Increasing protein content
B. Reducing microbial growth
C. Breaking waxy cuticle for water loss
D. Increasing sugar concentration
Correct Answer: C. Breaking waxy cuticle for water loss
Explanation: Chemical drying agents (like potassium carbonate) disrupt the waxy cuticle on the stems of legumes, allowing internal moisture to escape much faster.
10. Silage is preserved by which process?
A. Aerobic respiration
B. Alcoholic fermentation
C. Anaerobic fermentation
D. Oxidative rancidity
Correct Answer: C. Anaerobic fermentation
Explanation: Silage preservation depends on anaerobic (oxygen-free) conditions where lactic acid bacteria convert plant sugars into acids that “pickle” the forage.
11. Ideal dry matter content for ensiling forage is:
A. 15–20%
B. 25–30%
C. 30–35%
D. 40–45%
Correct Answer: C. 30–35%
Explanation: Forage with 30–35% dry matter (65–70% moisture) ferments best. Too much moisture leads to nutrient leaching (effluent), while too little prevents proper compaction.
12. Major acid responsible for good quality silage is:
A. Acetic acid
B. Butyric acid
C. Lactic acid
D. Propionic acid
Correct Answer: C. Lactic acid
Explanation: Lactic acid is the strongest and most efficient acid in silage. It drops the pH rapidly, preventing the growth of spoilage-causing microbes.
13. Unpleasant rancid butter smell in silage is due to excess:
A. Acetic acid
B. Lactic acid
C. Ammonia
D. Butyric acid
Correct Answer: D. Butyric acid
Explanation: Butyric acid is produced by Clostridia bacteria when the silage is too wet or contaminated with soil. It has a foul, rancid butter odor and indicates poor quality.
14. Most common silage inoculant used is:
A. Enterococcus coli
B. Lactobacillus plantarum
C. Clostridium spp.
D. Bacillus subtilis
Correct Answer: B. Lactobacillus plantarum
Explanation: L. plantarum is a homofermentative bacterium. It is added to forage to ensure a rapid, dominant lactic acid fermentation phase.
15. Recommended pH of good quality silage is:
A. 2.5–3.0
B. 3.7–4.2
C. 4.8–5.5
D. 6.0–6.5
Correct Answer: B. 3.7–4.2
Explanation: In cereal/maize silage, a pH between 3.8 and 4.2 is ideal. This high acidity is sufficient to inhibit all further microbial activity and preserve the nutrients.
16. Chaff size of maize plant for silage should be:
A. 5–7 cm
B. 3–5 cm
C. 1–3 cm
D. <1 cm
Correct Answer: C. 1–3 cm
Explanation: Chopping to 1–3 cm allows for better compaction (removing air) and improves the surface area for bacterial action, while still providing enough “effective fiber” for the ruminant.
17. In grab test, forage ball falls apart rapidly indicates moisture:
A. >75%
B. 70–75%
C. 60–70%
D. <60%
Correct Answer: D. <60%
Explanation: The grab test is a field method to estimate moisture. If the squeezed ball springs apart instantly, the forage is too dry (<60% moisture) for proper ensiling.
18. Best crop for silage making is:
A. Wheat
B. Maize
C. Oat
D. Barley
Correct Answer: B. Maize
Explanation: Maize (Corn) is the ideal silage crop because it contains high levels of soluble sugars (for fermentation) and high energy content from the grain.
19. Vitamin most lost during hay making is:
A. Vitamin D
B. Vitamin E
C. Vitamin A
D. Vitamin K
Correct Answer: C. Vitamin A
Explanation: Vitamin A (as carotene) is highly sensitive to sunlight and oxygen. Prolonged sun-curing can destroy up to 80% of the carotene in the forage.
20. Brown color of hay is due to:
A. Oxidation reaction
B. Caramelization
C. Maillard reaction
D. Lipid peroxidation
Correct Answer: C. Maillard reaction
Explanation: The Maillard reaction occurs when hay is baled too wet. The heat generated causes sugars to react with proteins (amino acids), turning the hay brown and reducing protein digestibility.
21. Amino acid most susceptible to Maillard reaction is:
A. Methionine
B. Lysine
C. Tryptophan
D. Glycine
Correct Answer: B. Lysine
Explanation: Lysine has a free epsilon-amino group that reacts easily with reducing sugars under heat, making it the most vulnerable amino acid during poor hay storage.
22. Moisture content of haylage is:
A. 20–30%
B. 30–40%
C. 45–55%
D. 60–70%
Correct Answer: C. 45–55%
Explanation: Haylage is intermediate between hay and silage. It is wilted to about 45–55% moisture before being baled and wrapped in plastic for fermentation.
23. Flieg index is used to evaluate:
A. Hay quality
B. Straw digestibility
C. Silage quality
D. Protein efficiency
Correct Answer: C. Silage quality
Explanation: The Flieg Index is a score calculated based on the concentrations of lactic, acetic, and butyric acids, as well as pH, to determine the fermentation quality of silage.
24. Ratio of grass/cereal to legume in silage mixture should be:
A. 1:1
B. 2:1
C. 3:1
D. 4:1
Correct Answer: C. 3:1
Explanation: Legumes are harder to ensile because they are low in sugar and high in buffering capacity. Mixing them with cereals in a 3:1 ratio provides enough sugar for successful fermentation.
25. Main cation of extracellular fluid is:
A. Potassium
B. Calcium
C. Sodium
D. Magnesium
Correct Answer: C. Sodium
Explanation: Sodium (Na+) is the primary cation in the extracellular fluid (ECF), while Potassium (K+) is the primary cation inside the cells (ICF). This balance is vital for nerve and muscle function.