A study published in December 2026 in Poultry Science, Volume 105, Issue 12, examines how immunocastration and testosterone supplementation alter testicular development and muscle collagen gene expression in male chickens.

The paper, authored by Xiao Zhang, Kota Hoshina, Miyu Uemori, Shiro Egawa, Shotaro Nishimura, and Yoshinao Z. Hosaka, addresses two linked questions in poultry production: how immunological suppression of testicular function reshapes reproductive tissue, and how the same interventions reach into breast and skeletal muscle through collagen-related gene expression.

Why does this matter at the farm level?

Immunocastration has gained traction across livestock sectors as an alternative to surgical castration, and the technique carries direct relevance for poultry operations where male birds are raised for meat. The study's focus on collagen gene expression signals an interest in connective tissue biology within muscle — a determinant of meat texture and processing quality.

By pairing the immunocastration protocol with testosterone supplementation, the authors designed the work to separate the effects of suppressed gonadal function from the effects of androgen replacement. That design allows practitioners and researchers to trace which changes in muscle tissue follow from the hormone environment and which follow from the immune intervention itself.

What did the study cover?

According to the publication record, the investigation spans:

• Testicular development in male chickens following immunocastration
• Testicular response under concurrent testosterone supplementation
• Gene expression changes in muscle collagen
• The interaction between gonadal suppression and androgen replacement

The authors report their findings in Poultry Science, Volume 105, Issue 12, the journal's December 2026 issue.

What are the practical implications?

For poultry veterinarians and production specialists, the work adds to the body of evidence on non-surgical methods of controlling male reproductive physiology. Connective tissue remodeling in muscle, mediated through collagen gene expression, sits at the intersection of endocrine status and carcass quality — a pairing that determines economic outcomes in broiler and rooster production systems.

The inclusion of a testosterone-supplemented group also gives the study comparative value: any practice considering hormonal modulation in male birds must weigh reproductive suppression against the downstream effects on muscle composition.

Full methodological detail, including sample sizes, dosing protocols, and statistical results, appears in the complete article in Poultry Science. Practitioners seeking the exact gene targets and quantitative expression data should consult the primary publication, as the present summary reflects the information available in the publication record.

Subsequent work building on these findings will likely clarify whether the collagen expression changes measured here translate into measurable differences in meat quality traits under commercial conditions.