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Bovine Herd Health Flashcards

7 cards from real NAVLE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Bovine Herd Health flashcards as text

  1. A herd of stocker cattle develops red-water disease (bacillary hemoglobinuria). Which organism and predisposing factor is responsible?

    Answer: Clostridium haemolyticum, liver fluke migration

    Bacillary hemoglobinuria is caused by C. haemolyticum (C. novyi type D), which proliferates in anaerobic zones created by migrating Fasciola hepatica liver flukes.

  2. Which reproductive toxin produced by endophyte-infected tall fescue grass causes 'summer slump' and reduced pregnancy rates in beef cows?

    Answer: Ergovaline

    Ergovaline from the Neotyphodium coenophialum endophyte causes vasoconstriction, hyperthermia, and poor reproductive performance in cattle grazing infected fescue.

  3. A dairy producer wants to monitor transition cow health. Which single blood test best predicts subclinical ketosis in fresh cows?

    Answer: Serum beta-hydroxybutyrate (BHB) ≥1.2 mmol/L

    Serum BHB ≥1.2 mmol/L (1.0–1.4 mmol/L threshold range) measured in the first 2 weeks postpartum is the gold standard for diagnosing subclinical ketosis.

  4. Anaplasmosis in cattle is transmitted primarily by which vector in the US?

    Answer: Dermacentor andersoni and Dermacentor variabilis ticks

    Anaplasma marginale is transmitted by Dermacentor tick species in the US, though mechanical transmission by biting flies and blood-contaminated instruments also occurs.

  5. A beef herd in the southeastern US has calves born with contracted tendons, cleft palate, and arthrogryposis. The dam grazed lupine between days 40–70 of gestation. Which teratogen is responsible?

    Answer: Anagyrine (quinolizidine alkaloid in lupine)

    Anagyrine in lupine species causes crooked calf disease (arthrogryposis and cleft palate) when dams graze lupine between days 40 and 70 of gestation.

  6. When calculating the economic impact of mastitis in a dairy herd, which production loss component is typically the largest?

    Answer: Reduced milk production (discarded milk + production drop)

    Reduced milk yield accounts for approximately 60–70% of total mastitis costs; clinical and subclinical cases each cow produces significantly less milk throughout the lactation.

  7. A veterinarian is conducting a pre-breeding soundness exam (BSE) on a herd bull. According to the Society for Theriogenology minimum standards, what minimum total motility percentage is required for a 'satisfactory' classification?

    Answer: 30% progressively motile sperm

    The SFT BSE minimum requires ≥30% progressively motile sperm and ≥70% morphologically normal sperm for a satisfactory potential breeder classification.