NAVLE Bovine Herd Health Management 3

Question 1

A dairy herd has a transition cow period disorder rate of 25% for clinical ketosis. Which nutritional management strategy is most effective at reducing periparturient ketosis?

Accepted Answer

Feeding propylene glycol as a preventive drench in the close-up dry period

Answer

Propylene glycol is a glucogenic precursor that, when drenched preventively in the close-up period or early postpartum, reduces the incidence of clinical ketosis by supporting hepatic gluconeogenesis.

Question 2

Which test is used to diagnose pregnancy toxemia (ketosis) in beef cows and can be performed on-farm using a handheld meter?

Accepted Answer

Blood beta-hydroxybutyrate (BHB) measurement

Answer

Handheld ketone meters measuring blood beta-hydroxybutyrate (BHB) provide rapid on-farm diagnosis of subclinical and clinical ketosis, with subclinical ketosis defined as BHB ≥1.2 mmol/L.

Question 3

A beef producer reports that 20% of his cows are losing calves due to abortion in the second trimester. Fluorescent antibody testing of aborted fetal tissues confirms Neospora caninum. What is the most likely source of infection in this cow-calf herd?

Accepted Answer

Ingestion of feed or water contaminated with dog feces containing oocysts

Answer

Dogs are the definitive host for Neospora caninum and shed oocysts in feces; cattle are infected by ingesting contaminated feed or water, making canine fecal contamination the primary horizontal transmission route.

Question 4

What is the recommended minimum colostrum quality (Brix refractometer reading) indicating adequate IgG concentration for feeding to neonatal calves?

Accepted Answer

≥22% Brix

Answer

A Brix refractometer reading of ≥22% correlates with IgG concentrations ≥50 g/L, which is the threshold for high-quality colostrum suitable for feeding neonatal calves.

Question 5

A veterinarian is establishing a herd health program for a 500-cow dairy. Which parameter best defines 'failure of passive transfer' (FPT) in dairy calves?

Accepted Answer

Serum IgG <10 g/L measured at 24-48 hours of age

Answer

FPT is defined as serum IgG <10 g/L (or serum total protein <5.2 g/dL as a surrogate) measured at 24-48 hours of age, after the gut closes to macromolecular absorption.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Bovine Herd Health Management 3