ICAR AIEEA (PG): Master's entrance, Veterinary Science and Animal Sciences · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersThe rumen and how to feed cattle, buffalo, sheep and goats through each stage of life, including ration formulation by the Pearson square and least-cost methods.
In the exams: ICAR AICE-JRF core group 05; ICAR AIEEA-PG 14 (Animal Nutrition)
ICAR AIEEA (PG), Code 14 Animal Sciences (Animal Nutrition)
Rumen microbes and VFA proportions, fate of acetate, propionate and butyrate, ammonia and microbial protein, RDP/RUP, feeding standards and thumb rules, Pearson square and DM conversion, colostrum and calf feeding, silage pH and quality indicators, deficiency diseases and urea feeding.
How our questions for ICAR AIEEA spread across the units of Applied Animal Nutrition I: Ruminants. Difficulty: 17 easy, 28 medium, 4 hard.
| Rumen ecosystem and function | 5 | |
| Nutrient requirements and feeding standards (ICAR 2013, NRC and NASEM) | 5 | |
| Least-cost ration formulation | 5 | |
| Rumen manipulation | 4 | |
| Ration formulation by the Pearson square | 4 | |
| Feeding of calves | 4 | |
| Feeding of heifers | 4 | |
| Feeding of lactating animals | 4 | |
| Evaluation of silage and hay | 4 | |
| Area-specific mineral mixtures | 4 | |
| Clinical nutrition | 4 | |
| Feeding of dry animals | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
On a predominantly forage diet, which volatile fatty acid is present in the rumen in the highest molar proportion?
A. Acetic acid, at roughly two-thirds of total VFA
Forage diets give about 65 to 70 percent acetate, 15 to 20 percent propionate and about 10 percent butyrate. Propionate rises with starch feeding, and lactic acid accumulates only in acidosis.
Further reading: Van Soest, Nutritional Ecology of the Ruminant, 2nd ed.
Which volatile fatty acid is the main substrate for hepatic gluconeogenesis in the ruminant?
D. Propionate
Propionate is converted to glucose in the liver. Acetate is the main precursor of milk and body fat, and butyrate is largely converted to beta-hydroxybutyrate in the rumen wall.
Further reading: McDonald et al., Animal Nutrition, 7th ed.
A grazing cow eats 300 MJ of gross energy a day. If 6 percent of gross energy is lost as methane, how much energy is lost as methane each day?
A. 18 MJ
300 × 0.06 = 18 MJ per day. 1.8 MJ comes from a decimal slip (0.6 percent), 50 MJ from dividing 300 by 6, and 6 MJ from writing the percentage as the answer. Methane losses are commonly 2 to 12 percent of GE.
Further reading: McDonald et al., Animal Nutrition, 7th ed.
The main reason for limiting total dietary fat in a dairy ration to about 6 to 7 percent of dry matter is that higher levels:
B. depress fibre digestion in the rumen and can lower milk fat
Unsaturated fatty acids coat fibre and are toxic to cellulolytic bacteria, reducing fibre digestion and feeding the trans-10 pathway of milk fat depression. Rumen-inert fats are used to add energy with less effect. Milk fever and ketosis are not caused by dietary fat in this way.
Further reading: McDonald et al., Animal Nutrition, 7th ed.
Physically effective NDF (peNDF) in a ration is calculated as:
A. NDF times the proportion of particles large enough to stimulate chewing
peNDF = NDF × physical effectiveness factor, often estimated as the proportion of DM retained on specified sieves. NDF minus ADF approximates hemicellulose, not peNDF.
Further reading: NRC, Nutrient Requirements of Dairy Cattle, 2001; NASEM 2021
For large-breed dairy heifers in intensive systems, the commonly targeted age at first calving is:
C. 22 to 24 months
22 to 24 months balances rearing cost with heifer size. Indigenous cattle and buffalo under smallholder conditions often calve at 30 to 40 months or later, mostly because of poor feeding.
Further reading: NRC, Nutrient Requirements of Dairy Cattle, 2001; NASEM 2021
In early lactation, the dairy cow is usually in negative energy balance because:
B. milk yield peaks before dry matter intake does
Milk peaks at about 6 to 8 weeks while DMI peaks later, so the cow mobilises body fat to fill the gap. Colostrum and early milk are not low in energy, and maintenance needs do not fall.
Further reading: NRC, Nutrient Requirements of Dairy Cattle, 2001; NASEM 2021
A cow receives 4 kg of concentrate mixture containing 2 percent mineral mixture. How much mineral mixture does she get per day from the concentrate?
B. 80 g
4 kg × 0.02 = 0.08 kg = 80 g. 8 g and 800 g are decimal slips; 20 g takes 2 percent of 1 kg.
Further reading: ICAR, Nutrient Requirements of Animals, 2013; Banerjee, A Textbook of Animal Husbandry
A cow with subclinical ketosis in early lactation would be expected to have a blood beta-hydroxybutyrate concentration of at least about:
D. 1.2 mmol/L
Blood BHB of about 1.2 mmol/L or more is the widely used cut-off for subclinical ketosis, with about 3.0 mmol/L for clinical ketosis; exact thresholds vary slightly. 0.5 mmol/L is normal.
Further reading: Constable et al., Veterinary Medicine, 11th ed.
Subacute ruminal acidosis (SARA) is usually defined by rumen pH remaining below about which level for several hours a day?
D. 5.5 to 5.8
SARA is commonly defined as rumen pH below about 5.5 to 5.8 for several hours daily; acute lactic acidosis reaches about 5.0 or lower. pH 6.8 to 7.0 is normal on forage; 3.5 to 3.8 is silage pH.
Further reading: Constable et al., Veterinary Medicine, 11th ed.
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