Nutritional requirements of broodmares

Without a doubt, the nutritional status of the broodmare is a critical component in the growth, development and health of the foal from the moment of conception through to weaning and even racing.

The Period of Gestation
Prior to the latest publication of the National Research Council of the most recent version of Nutrient requirements of Horses, industry professionals divided a mare’s gestation into two distinct nutritional periods namely from the time a mare was in foal to about 8 months (early gestation) often referred to as the first and second trimesters of pregnancy and the period from 9 to 11 months or birth (late gestation) or the third trimester.

The nutritional requirements of a mare during the first and second trimesters were similar and equivalent to those of any mature horse at maintenance. During the last trimester, an increase in certain nutrients such as energy and protein, as well as certain key minerals was recommended during the time of most rapid foetal growth. The most recent research has indicated however that whereas the nutrition requirements of mares should remain the same during the first 4 months of gestation, certain vital nutrients should be increased gradually during the middle term (5 to 8 months of pregnancy). The research that brought about this change took into account not only maintenance of the mare’s body weight and foetal growth, but also the nutritional expenditures involved in certain non-foetal tissues during gestation such as the creation and development of the mare’s placenta and mammary glands.

In order to support the development and maintenance of these non-foetal tissues during mid-pregnancy, it is recommended that protein and energy intakes are raised around 10% to 20% above the early gestation level from the 5th month of gestation onwards. There is no change to the previous nutritient requirements during late pregnancy (9 to 11 months) and this is a time when energy, protein, amino acid but especially mineral intakes need to increase.

The following gives an indication of the latest recommended daily nutritional requirements for a 500kg Thoroughbred broodmare in good health and body condition (National Research Council 2007).

Mares During Lactation
The mare’s nutritional requirement during lactation is based on the requirements required to maintain the mare in optimal body condition and the nutrients necessary for milk production. In early lactation the 500 kg mare must produce 15 – 20kg of milk each day with the nutrients needed to help the foal grow at over 1.5kg per day.

So great are the energy demands of the mare during early lactation (first 3 months), few performance horses require more energy. The energy, protein and mineral requirements for lactating mares have been reviewed upwards according to latest research during both early and late lactation.

The table below gives an indication of the mare’s nutrition requirements during lactation compared with the requirements in early pregnancy.

Feeding The Broodmare
Well tendered high quality pastures goes a long way in supplying mares with sufficient calories (energy) to nourish foetal growth during gestation and produce optimal quantities of high quality milk during lactation.

A mare’s feeding programme should be adjusted to accommodate the differences in requirements throughout gestation and lactation and to supply what she can’t get from pasture.

Possibly the best method of achieving this in practice, is using a feeding method which include both a balancer which is a low intake concentrate source of essential protein, vitamins and minerals designed for all classes of horses when additional calories are not required (Capstone Life Time Balancer pellet) and a fully fortified complete feed (Capstone Stud Time or Perform Time pellets) as these also contain not only the protein, vitamins and minerals required for the animal but also the energy.

Capstone Life Time Balancer can also be fed alone to horses that are maintained on all forage diets, or added to mixes when additional nutritional fortification is required, or fed with grains to provide the correct balance of nutrients in the daily ration.

A fully fortified feed such as Capstone Stud Time is fed at a higher intake than a balancer such as Capstone Life Time Balancer pellet (approximately 4 – 5 kg’s vs. 1.0 kg per horse per day). Both feeds must be fed in conjunction with a good quality forage source such as hay or pasture fed at between 1.0%(min) to 1.5% of bodyweight per day.

For mares that do not require such a high intake of a fully fortified feed (Capstone Stud Time), but do not maintain their bodyweight on a balancer alone (Capstone Life Time Balancer), one uses a mixture of both feeds, adjusting energy levels as required during the breeding season. Feed intakes of either feed will thus vary depending on stage of gestation and lactation and the changing requirements of each individual mare. This feeding system is designed to maintain a constant nutrient intake, while adjusting for energy requirement and works very well.

Such a feeding programme ensures the mare is maintained on an appropriate base nutrient package throughout all phases of reproduction and enables each mare to be fed individually. The experts at Kentucky Equine Research recommend that one regularly assesses the mare’s body condition score throughout all phases of reproduction, modifying energy intake as necessary to maintain the mare in the ideal good but not fat body condition.