Student Case Presentation
Evaluation of Passive Transfer Using Total Solids and the Influence of Sampling Timing in Dairy Calves
| Date/Time: |
8/27/2026 Poster 09
|
| Presenter: |
Emily Ferrari |
| Veterinary School: |
TUF |
Abstract:
The AABP recognizes that transfer of passive immunity is a critical determinant of calf health and long-term productivity within the dairy system across the United States. This project evaluated passive transfer in neonatal calves using total solids (TS) measurements collected from a commercial dairy herd between 2020 and 2025 and had the aim of exploring the relationship between the timing of sampling and TS measurements. Total solid measurements were obtained from serum samples collected weekly and read on an optical refractometer. Temporal factors potentially influencing TS measurements were evaluated, including month, season, year, day of year, birth day of month, birth day of week, and calf age at sampling. Across the five-year study period, TS did not significantly vary across months, seasons, and years, showing that the herd had stable colostrum management. The only statistically significant pattern found was calf age at time of sampling. Calves sampled at ≤3 days of life were substantially more likely to receive an ‘Excellent’ (>6.2 TS) passive transfer classification, compared with calves sampled at ≥4 days of life who showed greater numbers of ‘Good’ (5.8-6.1 TS) and ‘Fair’ (5.1-5.7 TS) scores. Sampling in the older group of calves demonstrated a trend toward decreased serum TS concentrations, representing lower estimated IgG and passive immunity. These findings suggest that timing of serum collection may influence TS classification and highlight the importance of consistent sampling protocols when monitoring passive transfer in dairy calves.
