Growth of the foetus begins from the point of conception and gradually accelerates so that the most rapid development occurs during the final trimester (third) of pregnancy.
Baileys have always advocated correct nutrition throughout pregnancy, since nutrients are not only required to support the growing foetus but also the development of the placenta, uterus and mammary glands as well as ensuring internal reserves are built up for both mare and foal after birth. The health of the mare’s placenta is crucial to the transfer of nutrients from the mare to the foetus.
Whilst “inadequate” nutrition may not lead to immediate apparent problems, long term shortfalls of nutrients or depletion of internal reserves could affect the development of subsequent foals. Inadequate nutrition during pregnancy has however been attributed to prolonged gestation, developmental abnormalities and low birth weights.
Good nutrition is also important at conception to ensure correct hormonal responses to support the pregnancy and, whilst excessive weight gain in the mare is to be avoided, recent research is suggesting that some weight gain during mid-gestation is necessary to provide an energy source for use in late gestation and early lactation. Over-feeding the mare will not produce a foal with a higher birth weight, but is more likely to increase the risk of problems during foaling.
Indeed, a separate study has also shown that maternal weight loss during mid-gestation had a direct effect on the mare’s blood insulin and glucose levels and those of the foal at birth, giving a strong indication of the link between mare nutrition and the subsequent health and viability of the foal. A link has also been shown between the feeding of a seleno-yeast, like Sel-Plex® which is included in Baileys Stud feeds, and increased levels of immunoglobulin (antibodies) in the mare’s colostrum and subsequently in the foal’s blood serum.
The mare’s diet should include a balance of nutrients, including essential amino acids, provided by quality protein sources, vitamins and both major (macro) and trace (micro) minerals. Research in New Zealand showed a higher incidence of growth problems in foals when the pre and post natal diets of the mares contained adequate levels of major minerals but below recommended allowances of trace minerals (Ref 8). Even mares looking well on pasture should receive supplementary nutrition as no modern forage is going to meet the major and trace mineral requirements of a pregnant mare on its own.