NAVLE Bovine Herd Health Management 4 — Questions and Answers
Question 1: A veterinarian is performing a herd reproductive evaluation. Which metric best represents overall reproductive efficiency in a beef cow-calf operation?
- Conception rate to first service
- Pregnancy rate per estrous cycle (PR/EC)
- Percentage of cows pregnant by 90 days post-calving (21-day pregnancy rate) (Correct answer)
- Bull-to-cow ratio during the breeding season
Correct answer: Percentage of cows pregnant by 90 days post-calving (21-day pregnancy rate)
The percentage of cows pregnant by 90 days post-calving (equivalent to a 90-day breeding season) measures overall reproductive efficiency by accounting for both conception rate and submission rate.
Question 2: Foot rot (Fusobacterium necrophorum infection) is common in beef feedlots. Which environmental management change has the greatest impact on reducing foot rot incidence?
- Prophylactic copper sulfate foot baths for all cattle
- Reducing mud and standing water in pen areas to minimize skin maceration (Correct answer)
- Routine zinc supplementation in the diet
- Trimming hooves every 60 days on all feedlot cattle
Correct answer: Reducing mud and standing water in pen areas to minimize skin maceration
Wet, muddy conditions cause skin maceration between the claws, allowing Fusobacterium necrophorum to invade; pen drainage and mud management are the most impactful environmental interventions.
Question 3: A dairy herd has a high prevalence of digital dermatitis (Mortellaro's disease). Which treatment is most effective for active, painful lesions?
- Systemic oxytetracycline injection
- Topical oxytetracycline applied to the lesion and wrapped with a bandage (Correct answer)
- Hoof trimming and copper sulfate footbath only
- Surgical debridement under general anesthesia
Correct answer: Topical oxytetracycline applied to the lesion and wrapped with a bandage
Topical oxytetracycline or lincomycin applied directly to digital dermatitis lesions after cleaning and drying, covered with a bandage, achieves the highest cure rates for active M2 lesions.
Question 4: When designing a biosecurity protocol for a cow-calf operation, which practice is MOST important for preventing introduction of Bovine Leukemia Virus (BLV)?
- Vaccinating all incoming cattle with MLV BLV vaccine
- Testing all purchased cattle for BLV antibodies before introduction and segregating positives (Correct answer)
- Using prophylactic ivermectin treatment to prevent insect transmission
- Quarantining all incoming cattle for 14 days regardless of BLV status
Correct answer: Testing all purchased cattle for BLV antibodies before introduction and segregating positives
BLV is most effectively prevented by serological testing (AGID or ELISA) of all purchased cattle and excluding seropositive animals, since there is no approved vaccine in the US.
Question 5: A beef producer asks about strategies to reduce the use of medically important antimicrobials in the feedlot. Which intervention is the best alternative for reducing bovine respiratory disease (BRD) morbidity?
- Increasing the dose of antibiotics to prevent resistance
- Implementing metaphylaxis only for high-risk cattle combined with optimization of vaccination protocols (Correct answer)
- Eliminating all antibiotic use and relying on supportive care only
- Switching from injectable to in-feed antibiotics exclusively
Correct answer: Implementing metaphylaxis only for high-risk cattle combined with optimization of vaccination protocols
Targeted metaphylaxis in high-risk cattle combined with robust vaccination programs reduces BRD morbidity while minimizing overall antibiotic use, consistent with antimicrobial stewardship principles.
Question 6: Which reproductive technology is used to synchronize estrus in beef heifers and cows to facilitate fixed-time artificial insemination (FTAI) without heat detection?
- Gonadotropin-releasing hormone (GnRH) injection alone
- Ovsynch or Select Synch protocols combining GnRH, progesterone (CIDR), and prostaglandin F2α (Correct answer)
- Human chorionic gonadotropin (hCG) injection alone
- Melengestrol acetate (MGA) in feed for 14 days without any hormonal synchronization
Correct answer: Ovsynch or Select Synch protocols combining GnRH, progesterone (CIDR), and prostaglandin F2α
The 7-day CO-Synch+CIDR or Ovsynch protocols combining GnRH, a CIDR insert, and prostaglandin F2α synchronize follicular wave and luteal regression to enable fixed-time AI without heat detection.
Question 7: A dairy herd has a transition cow program. Which serum calcium concentration defines subclinical hypocalcemia (milk fever) in periparturient cows?
- <2.0 mmol/L (8.0 mg/dL) without clinical signs (Correct answer)
- <1.4 mmol/L (5.5 mg/dL) with clinical signs
- <2.5 mmol/L (10 mg/dL) within 7 days of calving
- <1.0 mmol/L (4.0 mg/dL) with recumbency
Correct answer: <2.0 mmol/L (8.0 mg/dL) without clinical signs
Subclinical hypocalcemia is defined as serum calcium <2.0 mmol/L (8.0 mg/dL) without overt clinical signs, and it predisposes cows to other periparturient disorders including metritis, displaced abomasum, and ketosis.
NAVLE Bovine Herd Health Management 4
A veterinarian is performing a herd reproductive evaluation.
Which metric best represents overall reproductive efficiency in a beef cow-calf operation?