Vet Med - Czech, 2026, 71(10):399-414 | DOI: 10.17221/78/2025-VETMED

The impact of 5% flaxseed supplementation on sex hormones, antioxidant status, and blood profile in female spotted deer during the breeding seasonOriginal Paper

Y Mesfer Alharbi ORCID...¹, A Ibraheem Alnuqaydan ORCID...², AKA Zaki ORCID...^1,3

¹ Department of Medical Biosciences, College of Veterinary Medicine, Qassim University, Buraidah, Saudi Arabia

² Zoo Supervisor, King Khalid Military City Under the Ministry of Defense, Hafar Al-Batin, Saudi Arabia

³ Department of Physiology, Faculty of Veterinary Medicine, Cairo University, Giza Square, Egypt

Phytoestrogens, such as those found in flaxseed, can mimic oestrogen and influence animal physiology. For spotted deer, an economically significant species in Saudi Arabia, information on how phytoestrogen-rich diets affect reproductive health and overall physiology is limited, particularly in captive zoo settings. This work aimed to clarify the effects of a 5% flaxseed dietary supplement on the sex hormone profile, antioxidant capacity, haematological parameters, and histological features of female spotted deer during the onset of the breeding season. Twelve female deer were separated into two groups: a control group fed a standard diet of alfalfa and pellets, and an experimental group receiving the same diet supplemented with 5% flaxseed for six weeks. Weekly measurements included body weight and feed intake. Blood samples were analysed for sex hormones (oestradiol, testosterone), sex hormone-binding globulin (SHBG), antioxidant enzymes, oxidative stress markers, complete blood count (CBC), and biochemical parameters. Ovarian and reproductive tract histology was also examined. Flaxseed supplementation significantly increased serum oestradiol (E2) levels and SHBG (P < 0.05), reducing the Free Androgen Index (FAI). It also significantly enhanced antioxidant enzyme activities (SOD and CAT). Haematologically, it increased red blood cell count but induced microcytic hypochromic erythropoiesis, suggesting possible iron chelation. A notable increase in eosinophils was observed. Histologically, reproductive tissues showed enhanced development in the flaxseed group. Incorporating 5% flaxseed into the diet of female spotted deer induces a significant oestrogenic shift, improves antioxidant defence, and enhances reproductive tissue morphology. However, it may also cause iron deficiency-like haematological changes and a potential allergic response. This suggests that flaxseed is a potent dietary tool for modulating reproduction in captive deer, but its application requires careful management to mitigate adverse effects.

Keywords: antioxidants; Axis axis; captive wildlife; erythropoiesis; lignans; oestradiol; phytoestrogens

Received: October 2, 2025; Revised: May 19, 2026; Accepted: May 19, 2026; Prepublished online: October 13, 2026; Published: October 15, 2026  Show citation