How do I nutritionally support my broodmare during pregnancy and to provide the unborn foal with the key nutrients required for development?

Within the last trimester of the pregnancy, the largest amount of growth of the foetus occurs within the mare, with over 60% of the growth occurring within this third of the pregnancy. However, the nutrient requirements of the mare increase before then, as early as the fifth month of pregnancy. This increase sees an increased demand for calories or digestible energy, protein and in particular the amino acids lysine and methionine which are important for tissue growth within the foal. Therefore in addition to pasture or forage, later in the pregnancy the mare should be supplied with an increasing plane of nutrition with concentrate feeds added to the diet. To ensure an adequate supply of all the required nutrients the diet may also be supplemented with multi-vitamin and mineral nutraceuticals.

In addition to increasing calorie and protein requirements, there are specific increases in the requirements for vitamins and minerals in the broodmare at this stage of the life cycle. The vitamin A and E requirements are elevated above normal for the whole of pregnancy. The amount of calcium and phosphorus needed in the diet increases throughout the gestation as they become deposited in the foetus during the process of bone growth and mineralization (endochondral ossification) 17% of the mature bone mineral content will be present at birth.

In addition to these nutrients, trace elements such as copper and potentially manganese, iron and zinc are built up in the liver of the foal for use after birth to support growth as these minerals are in poor supply in the mare’s milk. Studies have shown that copper supplementation of the pregnant mare can increase the copper store in the liver of the foal, the quantity of which is variable and unique to each individual foal at birth. The studies indicated that this could then have an effect on reducing susceptibility to developmental cartilage lesions as copper is vital for connective tissue formation and bone growth.