Animal Nutrition MCQs Set 4
76. In metabolic trials, the samples collected include:
A. Only feces
B. Only urine
C. Feces and urine
D. Blood and milk
Correct Answer: C. Feces and urine
Explanation: Unlike a simple digestibility trial which only measures what is lost in feces, a metabolic trial (or balance trial) measures the total intake and total output of nutrients. This requires collecting both feces and urine to calculate the retention of elements like nitrogen or minerals.
77. Castrated males are preferred in digestibility trials because:
A. Higher intake
B. Faster digestion
C. Separate collection of feces and urine
D. Less feed wastage
Correct Answer: C. Separate collection of feces and urine
Explanation: In metabolic studies, it is vital to prevent urine from contaminating fecal samples. Because castrated males (wethers or steers) have anatomical structures that allow for the use of collection harnesses or funnels to separate these two waste streams easily, they are the preferred experimental subjects.
78. Digestibility determination in poultry is difficult because:
A. High feed intake
B. Rapid metabolism
C. Cloacal excretion of feces and urine
D. Small body size
Correct Answer: C. Cloacal excretion of feces and urine
Explanation: Poultry possess a cloaca, a single common chamber where the digestive and urinary tracts meet. Because feces and urine are voided together as a single excreta, it is difficult to determine the digestibility of individual nutrients without specialized surgical procedures like colostomy.
79. Limiting amino acid in pigs is:
A. Methionine
B. Lysine
C. Threonine
D. Tryptophan
Correct Answer: B. Lysine
Explanation: A limiting amino acid is the one present in the shortest supply relative to the animal’s requirement. In typical cereal-based diets for swine, Lysine is almost always the first limiting amino acid, meaning protein synthesis stops once it is exhausted.
80. Limiting amino acid in sheep is:
A. Lysine
B. Valine
C. Methionine
D. Isoleucine
Correct Answer: C. Methionine
Explanation: For ruminants, especially wool-producing sheep, Methionine is often the first limiting amino acid. This is because wool is made of keratin, which is exceptionally high in sulfur-containing amino acids like methionine and cysteine.
81. Taurine is an essential amino acid for:
A. Dog
B. Pig
C. Cat
D. Poultry
Correct Answer: C. Cat
Explanation: Cats are obligate carnivores and lack the enzyme pathway to synthesize sufficient Taurine from other amino acids. A deficiency in cats leads to central retinal degeneration and dilated cardiomyopathy.
82. Branched-chain amino acids (BCAAs) include all EXCEPT:
A. Valine
B. Leucine
C. Isoleucine
D. Alanine
Correct Answer: D. Alanine
Explanation: The BCAAs are a group of three essential amino acids: Valine, Leucine, and Isoleucine. They are unique because they are primarily metabolized in the muscle rather than the liver. Alanine is a simple non-essential amino acid.
83. Dietary excess of tyrosine causes:
A. Liver necrosis
B. Eye lesions
C. Muscle degeneration
D. Fatty liver
Correct Answer: B. Eye lesions
Explanation: While amino acids are necessary, extreme toxicities can occur. In laboratory animals and specific livestock models, a massive excess of Tyrosine leads to a syndrome characterized by inflammatory eye lesions and skin plaques on the paws.
84. Essential fatty acid requirement in cats is fulfilled by:
A. Linoleic acid
B. Linolenic acid
C. Oleic acid
D. Arachidonic acid
Correct Answer: D. Arachidonic acid
Explanation: Most animals can convert linoleic acid into arachidonic acid. However, cats lack the desaturase enzyme activity necessary for this conversion, making Arachidonic acid a strictly essential dietary requirement for felines.
85. Caecotrophy is characteristic of:
A. Guinea pig
B. Rabbit
C. Horse
D. Cow
Correct Answer: B. Rabbit
Explanation: Caecotrophy (or “soft feces” eating) is the process where rabbits produce and ingest specialized nutrient-rich pellets from their cecum. This allows them to re-digest microbial protein and vitamins synthesized in the hindgut.
86. Prevention of coprophagy in rabbits leads to:
A. Increased growth
B. Increased nitrogen retention
C. Decreased protein utilization
D. Improved digestibility
Correct Answer: C. Decreased protein utilization
Explanation: If a rabbit is prevented from performing caecotrophy, it loses access to high-quality microbial protein and B-vitamins. This results in a significant decrease in nitrogen (protein) utilization and overall growth.
87. Caecotrophy in rabbits starts at age:
A. 1 week
B. 2 weeks
C. 3 weeks
D. 5 weeks
Correct Answer: C. 3 weeks
Explanation: Young rabbits begin to transition from a strictly milk-based diet to solid forage around 3 weeks of age. It is at this stage that their cecal fermentation begins and they start practicing caecotrophy.
88. Biological method of improving straw nutritive value includes:
A. Steam treatment
B. NaOH treatment
C. Cellulase enzymes
D. Pelleting
Correct Answer: C. Cellulase enzymes
Explanation: Biological treatments involve using living organisms or their products. Adding cellulase enzymes or white-rot fungi to break down the lignin-cellulose bond is a biological approach to making straw more digestible.
89. Alkali treatment of straw is a type of:
A. Physical method
B. Chemical method
C. Biological method
D. Nutritional method
Correct Answer: B. Chemical method
Explanation: Using chemicals like Sodium Hydroxide (NaOH) or Ammonia (NH3) to dissolve lignin and swell the cellulose fibers of straw is classified as a chemical method of improving nutritive value.
90. Combination of physical and chemical treatment is called:
A. Biological processing
B. Supplementation
C. Physio-chemical method
D. Fortification
Correct Answer: C. Physio-chemical method
Explanation: When two different modes of treatment are combined—for example, steaming (physical) and urea application (chemical)—it is referred to as a physio-chemical treatment method.
91. Autoclave operates at:
A. 100°C for 30 min
B. 121°C for 15 min
C. 160°C for 1 hour
D. 600°C for 2 hours
Correct Answer: B. 121°C for 15 min
Explanation: The standard setting for an autoclave to achieve sterilization is 121°C at 15 psi (pounds per square inch) for 15 minutes. This temperature is sufficient to kill even the most heat-resistant bacterial spores.
92. Instrument used to determine ash content is:
A. Hot air oven
B. Autoclave
C. Kjeldahl apparatus
D. Muffle furnace
Correct Answer: D. Muffle furnace
Explanation: To determine ash (total mineral content), a sample is heated in a muffle furnace at 550–600°C. This burns away all organic matter, leaving only the inorganic residue behind.
93. Kjeldahl digestion is performed at approximately:
A. 200–250°C
B. 300–350°C
C. 360–410°C
D. 450–500°C
Correct Answer: C. 360–410°C
Explanation: During the digestion phase of the Kjeldahl method, sulfuric acid is heated to its boiling point (with catalysts) to break down organic nitrogen. The optimal temperature for this process is roughly 360–410°C.
94. Good quality silage produced by lactic acid fermentation has pH:
A. Above 5.0
B. 4.8 or above
C. 4.2–4.5
D. 3.5–4.2
Correct Answer: D. 3.5–4.2
Explanation: In high-quality silage, lactic acid bacteria produce enough acid to drop the pH to between 3.5 and 4.2. This level of acidity inhibits the growth of butyric acid-producing bacteria and yeasts.
95. High ammonical nitrogen (>20%) in silage indicates:
A. Very good silage
B. Good silage
C. Fair silage
D. Poor fermentation
Correct Answer: D. Poor fermentation
Explanation: Ammonical nitrogen is a sign of protein breakdown (proteolysis). In well-preserved silage, it should be below 10%. A level above 20% indicates severe spoilage and poor fermentation.
96. Cottonseed cake maximum safe inclusion level is:
A. 5–10%
B. 10–15%
C. 15–20%
D. 20–25%
Correct Answer: D. 20–25%
Explanation: Cottonseed cake is a good protein source but contains gossypol, a toxic pigment. For adult ruminants, the maximum safe inclusion level in the total ration is usually around 20–25%.
97. Maximum safe inclusion of urea in ration is:
A. 0.5%
B. 1–2%
C. 3–4%
D. 5%
Correct Answer: B. 1–2%
Explanation: To avoid ammonia toxicity, urea should generally not exceed 1% of the total dry matter of the ration or 2–3% of the concentrate mixture.
98. Maximum safe inclusion of oil in ration is:
A. 1%
B. 2–3%
C. 4–5%
D. 6–7%
Correct Answer: B. 2–3%
Explanation: High levels of fat coat the fiber particles in the rumen and inhibit microbial activity. Therefore, added fats or oils should generally be kept between 2 and 3% of the total ration.
99. Wheat bran is classified as:
A. Protein supplement
B. Mineral supplement
C. Energy feed
D. Roughage
Correct Answer: C. Energy feed
Explanation: Wheat bran is a by-product of flour milling. While it has some protein and minerals (especially phosphorus), it is primarily utilized as a medium-energy concentrate or energy feed.
100. Sodium requirement as percentage of total dry matter is approximately:
A. 0.10%
B. 0.20%
C. 0.30%
D. 0.50%
Correct Answer: C. 0.30%
Explanation: Sodium is a vital electrolyte. For most livestock, a dietary inclusion of approximately 0.30% sodium (which often equates to roughly 0.5–1.0% common salt) is required to maintain osmotic pressure and nerve function.