Dr David Pascoe believes that nutrition is possibly the single most important element in a healthy horse. This belief is supported by Dr Jennifer Stewart BVSc BSc PhD Dip BEP MRCVS Equine Veterinarian and Consultant Nutritionist who has consulted with great success to trainers and studs in Turkey, Hong Kong, Singapore, NZ, India, Dubai and UAE, South Africa, Malaysia, Japan as well as Australia. Here, Dr. Stewart shares her tips with us on balanced nutrition.

Good Feeding for Better Breeding

The late pregnant mare: Mares and foals are sensitive to the amino acid content of their feed. The effects of amino acid imbalance are most pronounced during the last 90 days of pregnancy and the first 90 days of birth – when fetal and neonatal growth spurts occur. Quality hays are good feeds for broodmares, but the amino acids may need tweaking.

Winter: Energy requirements increase in winter because the digestible energy of winter pastures is low and energy requirements of mares increase by about 5% for every 1°C drop in temperature below 15°C. A recent study of 36 mares found that mares on high quality protein diets had higher levels of reproductive hormones, began cycling sooner and ovulated 4-6 weeks earlier than mares on low quality protein diets.

The lactating mare: Between 3 and 24% of mares have reduced quantity or quality of colostrum. It is especially important to have a veterinarian assess the colostrum in mares that run milk prior to foaling. If the pasture is unusually lush and improved or excessive amounts of starch are fed, there is greater risk of running milk and over-producing milk. The strong healthy foal that over-drinks may get gastro-intestinal overload, which can lead to diarrhoea. A mare’s milk production – both the amount and nutrient content – decreases as lactation progresses so that by the 5th month, the mare is supplying less than 30% of the foal’s energy needs. Providing a concentrate that includes oils and high quality protein will slow the downward trend in milk production and quality.

Breeding: In underfed mares, pregnancy rates over 3 cycles are only 50% and maintenance of pregnancy after 90 days only 25% compared to 100% in mares who are correctly fed. Incorrectly fed mares also have delayed return to cycling after birth and lower conception rates, even if well fed after birth and during lactation.

• Mares retiring from racing have better conception rates if they are bred straight away OR given 90 days to let down. In between they are harder to get in foal – often because they are accustomed to a stable, regular exercise and a high plane of nutrition. It is important to maintain energy intake as weight loss reduces fertility. Free choice hay – a mixture of lucerne and meadow – should be available and the amount of concentrate varies with mare body condition and the quality and quantity of roughage.
• Older mares take longer to begin cycling and have more multiple ovulations than young mares. Recently published research found that hormone levels are higher and cycling begins earlier when mares are fed a highly digestible, nutrient-dense fully steam extruded concentrate, such as Mitavite Promita, when compared to mares fed on oats.
• Thin mares: Mares need to be gaining weight to cycle regularly and produce plump, ripe follicles. Even when thin mares are fed recommended energy levels, only 46% ovulate – compared to 86% of thin mares fed at 150% of recommended energy.
• Fat mares: A fat mare who is not getting recommended energy intake may perform as poorly as the thin mare, so a weight reducing diet is not compatible with reproductive performance. Adjustments should be made after pregnancy is confirmed.
• Lactating mares – lactation often coincides with the 1st four months of gestation. Mares foaling in low body condition have impaired reproductive efficiency even if energy requirements for lactation are met.

OILS: Mares on diets enriched with oil and high in fibre, show less stress (as measured by blood cortisol, zinc, vitamin C and white blood cell levels) than mares on grain-based carbohydrate diets. High oil-high fibre feeds are also superior to grain and molasses concentrates in influencing milk composition in ways that improved foal health. Mares on the fat-fibre diets have elevated levels of linolenic acid – an omega 3 fatty acid believed to reduce the risk of foal stomach ulcers and increase in IgG in the colostrum – enhancing foal immunity.

Oil is used preferentially for milk production and provides an early growth advantage for foals. In addition, mares on oil-enriched feeds have shorter time to foal heat (12 vs 14 days), fewer cycles per conception (1 vs 2) and higher pregnancy rates (100 vs 89%)

The greatest risk periods for pregnancy loss are days 15-20 and 30-35 of pregnancy. In mares over 10 years of age, progesterone levels are higher between days 0-13 and 37-49 when supplementary oil is fed. This suggests that increasing the oil intake may increase progesterone concentration in pregnant mares over 10 years of age.

VITAMIN E: The NRC recommended vitamin E intake for pregnant and lactating mares is 80iu per kg of feed. Studies in 1999 found that feeding concentrates with 160iu of vitamin E, compared to 80iu for 4 weeks before foaling and 4 weeks after foaling enhances colostrum and blood levels of vitamin E.