CAC CAC Livestock & Animal Science 2 — Questions and Answers
Question 1: In swine production, what does the term 'pigs per sow per year' (PSY) measure?
- Average daily feed intake
- Reproductive efficiency of the sow herd (Correct answer)
- Slaughter weight of market hogs
- Number of boars needed per sow
Correct answer: Reproductive efficiency of the sow herd
PSY is the key productivity metric for swine operations, combining litter size, wean-to-service interval, and farrowing rate.
Question 2: Which condition describes mastitis in dairy cows caused by environmental pathogens such as E. coli or Klebsiella?
- Contagious mastitis
- Environmental mastitis (Correct answer)
- Subclinical mastitis
- Chronic mastitis
Correct answer: Environmental mastitis
Environmental mastitis is caused by pathogens the cow contacts in her surroundings, particularly in dirty bedding and stagnant water.
Question 3: A somatic cell count (SCC) below what threshold is generally accepted as indicating healthy mammary gland status in dairy cows?
- 50,000 cells/mL
- 200,000 cells/mL (Correct answer)
- 500,000 cells/mL
- 1,000,000 cells/mL
Correct answer: 200,000 cells/mL
An SCC below 200,000 cells/mL is considered indicative of a healthy, uninfected mammary quarter.
Question 4: The National Animal Identification System (NAIS) and its successor programs in the US are primarily designed to:
- Set commodity prices for livestock
- Enable rapid traceback during disease outbreaks (Correct answer)
- Regulate interstate hay transport
- License agricultural consultants
Correct answer: Enable rapid traceback during disease outbreaks
Animal ID and traceability programs allow USDA to quickly identify and contain disease outbreaks by tracing animal movements.
Question 5: What is the recommended withdrawal time purpose when using antibiotics in food animal production?
- To allow the animal to recover from illness
- To ensure drug residues clear tissue before slaughter or milking (Correct answer)
- To satisfy state licensing requirements
- To prevent vaccine interference
Correct answer: To ensure drug residues clear tissue before slaughter or milking
The withdrawal period allows the animal's body to metabolize and eliminate antibiotic residues to safe levels below FDA tolerances.
Question 6: In poultry production, what does the term 'feed conversion ratio' (FCR) represent?
- Ratio of protein to energy in feed
- Pounds of feed required to produce one pound of live weight gain (Correct answer)
- Percentage of feed waste in the barn
- Cost of feed per dozen eggs
Correct answer: Pounds of feed required to produce one pound of live weight gain
FCR measures feed efficiency; a lower FCR (e.g., 1.8) means the flock is converting feed to body weight more efficiently.
CAC CAC Livestock & Animal Science 2
In swine production, what does the term 'pigs per sow per year' (PSY) measure?