NAVLE Bovine Herd Health 2

Question 1

A beef cow herd has a 15% prevalence of Bovine Respiratory Disease (BRD) in newly arrived feedlot calves. Which metaphylactic antibiotic is most commonly used at arrival processing?

Accepted Answer

Tulathromycin

Answer

Tulathromycin (Draxxin) is a macrolide widely used for metaphylaxis in high-risk beef cattle due to its long tissue half-life and single-dose efficacy.

Question 2

Pinkeye (Infectious Bovine Keratoconjunctivitis) in a cow herd is most commonly caused by which organism?

Accepted Answer

Moraxella bovis

Answer

Moraxella bovis is the primary causative agent of IBK, producing a pilus that allows corneal attachment and a hemolysin that damages corneal epithelium.

Question 3

A dairy herd has an elevated somatic cell count (SCC) averaging 500,000 cells/mL. What SCC threshold is used by the USDA as the legal limit for Grade A milk in the US?

Accepted Answer

750,000 cells/mL

Answer

The US legal limit for bulk tank SCC in Grade A milk is 750,000 cells/mL, though the EU standard is stricter at 400,000 cells/mL.

Question 4

Which vaccination protocol is most effective for preventing Bovine Virus Diarrhea (BVD) in a cow-calf operation?

Accepted Answer

Modified live BVD vaccine given before breeding

Answer

MLV BVD vaccines given pre-breeding provide superior mucosal immunity and prevent fetal infection that leads to persistently infected (PI) calves.

Question 5

A rancher reports abortions in 8% of his beef cows in the last trimester. Brucella abortus is confirmed. Which test is used for the official US brucellosis eradication program to test individual cattle?

Accepted Answer

Card test (Rose Bengal plate test)

Answer

The card (Rose Bengal) test is the approved screening test in the US brucellosis eradication program, with positive reactors confirmed by the buffered acidified plate antigen (BAPA) or fluorescent polarization assay.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Bovine Herd Health 2