NAF Five Star Oestress Liquid 2L Refill. NAF Five Star Oestress Liquid is a unique complex of herbs that can help to balance the hormones in 'moody' mares. Oestress allows the mare to naturally correct her hormonal imbalance making her more inclined to relax and concentrate on her work. Oestress offers bio-available magnesium to help support the system against the anxiety and muscle tension often seen in hormonal mares and is rich in antioxidants to help flush toxins from the system. Oestress should be fed daily throughout the spring and summer season and may be increased in accordance with the mare's oestrus cycle. Read more… Can be fed all year round if needed. NAF Five Star Oestress Liquid is also suitable for geldings displaying 'riggy' behaviour. Horses and Ponies Recommended Daily Amounts Peak Rate (3-5days) - 75-100ml per day Maintenance Rate - 25-50ml per day 1 Litre fed at maintenance level should last approximately 40 days.