Fermex Field Study Update: First Bresse Offspring Weights
October 14, 2026 · Bryant’s Roost Supplement Field Study
We have a new starting point in our Fermex field study: the first individual weights from Bresse chicks produced by our breeding pens.
Today, we weighed and banded 30 chicks from four pens. The six chicks from Pen 5—the pen whose parent birds received Fermex in their feed beginning at hatch—had the highest average body weight at this first measurement.
That is an observation worth following, not proof that Fermex caused the difference.
Today’s Bresse chick weights
The chicks are approximately one week old. These measurements establish a baseline for following each bird over time.
| Breeding pen | Chicks | Mean weight |
|---|---|---|
| Pen 2 | 5 | 90.6 g |
| Pen 3 | 9 | 96.1 g |
| Pen 4 | 10 | 98.6 g |
| Pen 5 Fermex-fed parents | 6 | 108.2 g |
The 24 chicks from Pens 2, 3, and 4 averaged 96.0 grams combined. The six Pen 5 chicks averaged 108.2 grams—about 12.2 grams, or 12.7%, heavier at this first weighing. The combined comparison is calculated from all 24 individual weights, not a simple average of the three pen averages.
Heavier today does not yet mean faster growth
One weighing tells us what each chick weighs now. It does not tell us how quickly that chick gained weight. We need repeat measurements before we can compare growth rates.
Each chick now has an individual wing-band number, so future weigh-ins can follow the same birds rather than relying only on group averages.
What this comparison can—and cannot—tell us
This is an observational farm field study. Genetics, egg size, sex ratios, breeder performance, and other differences between pens may contribute to the weights we see.
There is only one Fermex-parent pen in this comparison. Its six chicks are six individual observations, not six independent treatment groups. That limits what we can conclude about the supplement.
We also need to keep parent supplementation separate from chick supplementation. The Pen 5 parents received Fermex as they grew and matured. Direct Fermex exposure of these offspring has not been established, so we are not presenting this as a trial of chicks being directly fed Fermex.
These weights do not establish a benefit in hatch rate, survival, or feed efficiency, and we are not attributing the weight difference to Fermex.
What we’ll follow next
Our next measurements will let us look at individual weight gain, how evenly the chicks grow, survival, and physical development. The important question is whether this early difference persists as the birds mature.
For now, we have a documented baseline and individually identified birds. We’ll keep reporting what we observe, including results that do not support a benefit. Promising observations are a reason to keep measuring—not a substitute for evidence.
Read the previous Fermex field study update or follow the full supplement field study.