FEEDING FOR BREEDING – PREGNANCY DIABETES OCCURS IN HORSES TOO! 

Courtesy of Jenquine.

Known as ‘gestational diabetes’ or GDM, pregnancy diabetes affects between 4 and 12% of women. An equivalent condition occurs in mares and increases their risk of pregnancy-associated laminitis. In both us and horses, the condition is associated with changes in blood glucose and insulin. 

At around 12 – 14 weeks pregnancy in women and 21 weeks (5 – 6 months) in mares, insulin sensitivity begins to drop – called ‘insulin resistance’. This is an evolutionary adaptation which means the mother’s tissues don’t respond normally to insulin – the role of insulin is to move glucose out of the blood and shift it into the body tissues. When the mare’s tissues develop insulin resistance, the amount of glucose they take from the blood reduces – so more glucose is diverted to the foetus and placenta.  We’ve often heard that ‘she gives it all to the foal’ and after the 5^th month of pregnancy, this is exactly what nature designed. The large demand for glucose by the growing foal is met by a reduction in the amount the mare uses.  

The choice of diet can protect or increase the hazards. Feeds containing starch/sugar are associated with insulin resistance, obesity and laminitis. Because pregnancy itself is associated with laminitis with the danger increasing after 5 months gestation, the risk is compounded in mares on feeds that are high in starch/sugar and further increased with processing methods that improve feed digestibility in the small intestine – as these processing methods increase blood glucose and insulin changes.  

Being a broodmare has been identified as a risk factor for obesity and laminitis and it can be hard to manage increasing body weight in pregnant mares. And it’s not just the effect of blood glucose and insulin levels on the hooves – additional stress on the feet comes from the increasing body weight borne by the hooves most of which occurs during early–mid pregnancy and is largely due to the development of the placenta and enlargement of the uterus. 

Diet management is important too for the foetal foal as it is affected by the amount of glucose and insulin in the mare’s bloodstream. Foals born to mares that are overweight, obese or fed sugar/starch concentrates have altered blood glucose and lower insulin sensitivity until at least 5 months and up to 18 months after birth – the greatest risk period for the initiation of DOD. Foals from mare’s fed starch/sugar concentrates during pregnancy are more susceptible to osteoarticular lesions – including all forms of developmental orthopaedic diseases (DOD) such as bone cysts, physitis and OCD.? 

Pregnant mares are commonly fed concentrates to provide the increased amino acid and mineral needs of pregnancy but energy requirements don’t increase significantly until lactation. All care must be taken to ensure the feed is low in starch and sugar and mares don’t become overweight. Diets based on fibre and oil have little effect on insulin and have been shown to protect against the development of laminitis in mares and DOD in foals. 

Feeding to match requirements is the fundamental principle. The risk of over-feeding is increased with complete feeds if the amount fed is increased to meet the increased vitamin and mineral needs of pregnancy. However, if a complete feed is fed below recommended amounts, it’s likely that there will be underfeeding of vitamins and minerals. Feeding a correctly formulated, complementary amino acid/mineral/vitamin/antioxidant supplement allows you to increase or decrease energy intake without compromising vitamin and mineral intake. Jenquine all-4-feet is a low starch, low sugar, amino acid and mineral rich complementary balancer for all diets.