American Registry of Professional Animal
Scientists (ARPAS) - Beef Cattle Specialist Exam
Practice
1. Which volatile fatty acid (VFA) is the primary substrate for gluconeogenesis in
the beef animal’s liver?
• A. Acetate
• B. Butyrate
• C. Propionate
• D. Lactate
Answer: C
Explanation: Propionate is the only major VFA that is glucogenic; it is cleared by the liver
and converted to glucose, providing the majority of the animal’s glucose needs.
2. In the Net Energy (NE) system, which energy fraction accounts for the heat
increment of fermentation and nutrient metabolism?
• A. Digestible Energy (DE)
• B. Metabolizable Energy (ME)
• C. Net Energy (NE)
• D. Gross Energy (GE)
Answer: C
Explanation: Net Energy is ME minus the heat increment (HI). HI includes heat from
fermentation and metabolic processes.
3. Which microbial species is primarily responsible for the rapid production of
lactic acid during the onset of ruminal acidosis?
• A. Fibrobacter succinogenes
• B. Megasphaera elsdenii
• C. Prevotella ruminicola
• D. Streptococcus bovis
Answer: D
Explanation: Streptococcus bovis is a rapidly growing amylolytic bacterium that produces
lactic acid when starch levels are high, leading to a drop in pH.
, 4. What is the primary mode of action for ionophores like monensin in the
rumen?
• A. Increasing Gram-negative bacteria populations
• B. Reducing the production of propionate
• C. Inhibiting the growth of Gram-positive bacteria
• D. Increasing methane production
Answer: C
Explanation: Ionophores selectively inhibit Gram-positive bacteria, shifting the microbial
population toward Gram-negative species which produce more propionate and less
methane.
5. In beef cattle genetics, what does the ‘Accuracy’ (ACC) value associated with
an EPD represent?
• A. The reliability of the EPD as an estimate of the true breeding value
• B. The percentage of the trait that is heritable
• C. The probability that the calf will survive to weaning
• D. The rank of the animal within the breed
Answer: A
Explanation: Accuracy is a measure of the reliability of an EPD, influenced by the amount
and quality of data (pedigree, performance, progeny) available.
6. Which hormone is produced by the corpus luteum (CL) and is essential for the
maintenance of pregnancy?
• A. Estrogen
• B. Prostaglandin F2a
• C. Luteinizing Hormone
• D. Progesterone
Answer: D
Explanation: Progesterone (P4) is secreted by the CL to maintain the uterine environment
required for pregnancy.
7. A deficiency in which mineral is most commonly associated with ‘Grass
Tetany’ in lactating cows grazing lush spring forage?
• A. Calcium
• B. Magnesium
• C. Phosphorus
• D. Potassium
Answer: B
Scientists (ARPAS) - Beef Cattle Specialist Exam
Practice
1. Which volatile fatty acid (VFA) is the primary substrate for gluconeogenesis in
the beef animal’s liver?
• A. Acetate
• B. Butyrate
• C. Propionate
• D. Lactate
Answer: C
Explanation: Propionate is the only major VFA that is glucogenic; it is cleared by the liver
and converted to glucose, providing the majority of the animal’s glucose needs.
2. In the Net Energy (NE) system, which energy fraction accounts for the heat
increment of fermentation and nutrient metabolism?
• A. Digestible Energy (DE)
• B. Metabolizable Energy (ME)
• C. Net Energy (NE)
• D. Gross Energy (GE)
Answer: C
Explanation: Net Energy is ME minus the heat increment (HI). HI includes heat from
fermentation and metabolic processes.
3. Which microbial species is primarily responsible for the rapid production of
lactic acid during the onset of ruminal acidosis?
• A. Fibrobacter succinogenes
• B. Megasphaera elsdenii
• C. Prevotella ruminicola
• D. Streptococcus bovis
Answer: D
Explanation: Streptococcus bovis is a rapidly growing amylolytic bacterium that produces
lactic acid when starch levels are high, leading to a drop in pH.
, 4. What is the primary mode of action for ionophores like monensin in the
rumen?
• A. Increasing Gram-negative bacteria populations
• B. Reducing the production of propionate
• C. Inhibiting the growth of Gram-positive bacteria
• D. Increasing methane production
Answer: C
Explanation: Ionophores selectively inhibit Gram-positive bacteria, shifting the microbial
population toward Gram-negative species which produce more propionate and less
methane.
5. In beef cattle genetics, what does the ‘Accuracy’ (ACC) value associated with
an EPD represent?
• A. The reliability of the EPD as an estimate of the true breeding value
• B. The percentage of the trait that is heritable
• C. The probability that the calf will survive to weaning
• D. The rank of the animal within the breed
Answer: A
Explanation: Accuracy is a measure of the reliability of an EPD, influenced by the amount
and quality of data (pedigree, performance, progeny) available.
6. Which hormone is produced by the corpus luteum (CL) and is essential for the
maintenance of pregnancy?
• A. Estrogen
• B. Prostaglandin F2a
• C. Luteinizing Hormone
• D. Progesterone
Answer: D
Explanation: Progesterone (P4) is secreted by the CL to maintain the uterine environment
required for pregnancy.
7. A deficiency in which mineral is most commonly associated with ‘Grass
Tetany’ in lactating cows grazing lush spring forage?
• A. Calcium
• B. Magnesium
• C. Phosphorus
• D. Potassium
Answer: B
