A new comparison of two dairy calf weaning timelines — 3 weeks versus 6 weeks — appears in the October 2026 issue of the Journal of Dairy Science, with researchers tracking plasma bile acid concentrations across the transition in calves fed milk replacer ad libitum. Volume 109, Issue 10 carries the paper, signed by M.H. Ghaffari, A. Stoschus, L.E. Diesing, S. Schuchardt, and H.M. Hammon.

By the numbers

• 2 weaning endpoints: 3 weeks and 6 weeks
• 100% difference in liquid-feeding duration between the two groups
• 1 marker: plasma bile acid concentration, tracked longitudinally
• 5-author team, led by Ghaffari
• Published October 2026 in Journal of Dairy Science, Volume 109, Issue 10

What did the study measure?

The title sets out a longitudinal comparison of plasma bile acid dynamics across the weaning window in calves weaned at 3 weeks versus 6 weeks, all on ad libitum milk replacer. That regime elevates fat intake and hepatic workload relative to restricted programs. The two endpoints bracket current commercial practice; the longer interval represents a 100% increase in liquid-feeding duration.

Calves on ad libitum milk replacer consume more fat and energy than those on restricted programs. Higher fat intake drives bile secretion to emulsify lipids, altering plasma bile acid pools. When weaning ends the high-fat liquid diet, bile acid dynamics shift again, and the study design captures both transitions across two end dates.

Why track bile acids at weaning?

Plasma bile acids rise and fall with feed intake, intestinal absorption and hepatic clearance — all three shift at once during weaning. The marker therefore functions as an integrated read on how a calf's liver and gut handle the dietary change. In adult transition dairy cows, bile acid measurement has established clinical value. In pre-weaning calves, the evidence base remains thin, which is what makes a focused longitudinal study on the marker worth attention.

What changes at the exam table or in the barn?

The full text will determine the specific findings, but the experimental design maps directly onto three decisions dairy producers and their veterinarians face routinely:

• Minimum milk-feeding duration under ad libitum programs
• Age at which starter grain intake should accelerate for rumen development
• Whether to add hepatic markers to pre-weaning metabolic panels in poor-growth calves

For practitioners, the practical question is whether plasma bile acid measurement belongs alongside beta-hydroxybutyrate and non-esterified fatty acids as a weaning screening tool — and at which age the marker discriminates most clearly between early-weaned and extended-milk-fed cohorts.

What do the available materials include?

The publication notice provides the title, authorship and journal placement. The materials provided do not include numerical results, sample size or statistical comparisons, so the headline question sits as the study poses it: do 3-week and 6-week weaned calves show distinct bile acid trajectories? The full paper in Volume 109, Issue 10, will carry the specific values.

Why this paper, why now?

The October 2026 publication date places the work in an active research window for dairy heifer nutrition, where early and extended milk-feeding programs compete as commercial strategies. The Ghaffari-led comparison adds a hepatic-metabolism layer to that debate, and the full text is likely to drive the next round of practitioner questions about minimum milk-feeding duration, starter intake targets, and which calves merit metabolic screening around weaning.