I've owned Rosie for six years. She's a twelve-year-old Irish Sport Horse mare — talented, sensitive, and for most of the year, an absolute pleasure to be around. But for three or four months every spring and summer, she becomes a different horse. Spooky, tense, difficult to handle on the ground, unpredictable under saddle. The kind of behaviour that makes you question whether you're doing something wrong, whether she's in pain, whether the partnership you've built over years is actually as solid as you thought.
It took me two years to understand that what I was dealing with was hormonal. Mares can experience significant behavioural changes during their oestrus cycle — heightened sensitivity, tension, resistance, mood swings that have nothing to do with training or management and everything to do with physiology. Once I understood that, I could address it. NAF Five Star Oestress was the supplement that made the difference.
Two Years of Managing Rather Than Solving
Before I found Oestress, I managed the seasonal behaviour rather than addressing it. I adjusted my riding to work around Rosie's difficult days. I avoided certain exercises during the worst weeks. I was more cautious, less ambitious, less willing to push for the work I knew she was capable of. It was a reasonable adaptation, but it wasn't a solution — and it meant that for a significant portion of the year, I wasn't getting the best from either of us.
I'd tried a magnesium supplement that helped slightly with the tension but didn't address the hormonal root cause. I'd tried a general calming supplement that made her slightly dull without actually improving the behaviour. Neither was the right answer.
Why I Chose NAF Five Star Oestress
The NAF Five Star Oestress was recommended by my instructor, who had used it with her own mare and seen significant results. NAF is a brand I trust — they've been making equine supplements for decades and their Five Star range is formulated with genuine care for efficacy rather than just marketability.
The key ingredient is Chasteberry (Vitex Agnus Castus) — a botanical that has been used traditionally to support hormonal regulation in both horses and humans. It works by influencing the pituitary gland's production of hormones, helping to smooth out the peaks and troughs of the oestrus cycle rather than suppressing it entirely. Combined with magnesium — which supports muscle relaxation and nervous system function — and calming herbal extracts, the formula addresses both the hormonal cause and the physical symptoms of tension and sensitivity.
The 500g size was the right starting point: enough for a proper trial period without committing to a large supply before knowing whether it would work for Rosie specifically.
The First Cycle
I started Rosie on Oestress in early March, before the spring season properly began. The feeding instructions are straightforward — a measured amount added to her feed once daily. She accepted it without any fussiness, which matters: a supplement a horse won't eat is a supplement that doesn't work.
The first cycle after starting the supplement was noticeably different. Not dramatically — I want to be honest about that — but measurably. The tension that usually built through the week before she came into season was less pronounced. She was easier to handle on the ground. Under saddle, she was more focused and less reactive to things that would normally have caused a spook or a resistance.
By the second cycle, the improvement was more significant. By the third, I had my horse back.
What Changed
The specific changes I noticed: Rosie stopped being spooky at things she'd been fine with for years. The tension in her back — which I'd been managing with extra warm-up time and careful riding — reduced significantly. She became more consistent in her responses to the aids, which is the thing that matters most for training: a horse that responds the same way on Tuesday as she did on Monday is a horse you can make progress with.
She also became easier to handle on the ground during her difficult weeks — less reactive when being groomed, less tense when being tacked up, more willing to stand quietly. These are small things that compound: a horse that's easier to manage on the ground is a horse you approach with more confidence, and that confidence communicates itself in ways that make the horse calmer in return.
A Full Season On
I used Oestress through the full spring and summer season — approximately five months. The improvement was consistent throughout. I've since started her on it again this spring, earlier than last year, and the seasonal behaviour has been minimal compared to what it was before I found the supplement.
My instructor noticed the change without me mentioning it. At a lesson in May she said: "Rosie's going really well at the moment. Whatever you're doing, keep doing it." I told her it was the Oestress she'd recommended. She smiled. "It works, doesn't it."
The Difference It Made
I stopped dreading spring. That's the honest summary. For two years, the arrival of longer days and warmer weather had meant the beginning of a difficult season with a horse I loved but couldn't always manage. Now it means the beginning of the riding season with a horse I trust. That shift — from anxiety to anticipation — has changed how I approach every session with Rosie, and that change in my approach has made her better in return. The supplement didn't just help Rosie; it helped the partnership.
Who I'd Recommend This To
Any mare owner who has been managing seasonal hormonal behaviour rather than addressing it. Anyone whose mare is a different horse in spring and summer compared to autumn and winter. Anyone who has tried general calming supplements without success and needs something that addresses the hormonal root cause specifically. And anyone whose instructor or vet has suggested trying a chasteberry-based supplement and who wants a formulation from a brand with a proven track record in equine nutrition.
Start before the season begins if possible — the chasteberry takes a few weeks to build up in the system, and starting early means the supplement is working before the difficult behaviour begins rather than after. The 500g size is the right amount for a full trial period.
You can find NAF Five Star Oestress 500g in our store. It also sits within our Horse Vitamins & Supplements, Horse Care, Equestrian, and Outdoor Recreation collections if you'd like to explore more.
Start it early. Give it time. Get your mare back.
— Kate Saunders, Wiltshire
0 comentarios