When grass is never enough

'A Good Start in Life'

Without doubt, the most important period of a horses life is from birth through to two years of ages.  During this time a young horse can reach 90% of its adult height and 80% of its adult weight.  Good nutrition however begins with the pregnant broodmare. 

In New Zealand or horse breeding industry bases itself on pasture farming.  Spring grass is rich in energy and protein at the time of year when most mares are foaling and foals are suckling.

However alot of mares do not have ready access to abundant spring grass at foaling time, which the unborn foal requires.  If the mare foals in late spring or early summer the grass is of lower nutritional value.

There are two important periods to consider - the last three months of pregnancy, - the first 3 months of lactation.

For the first eight months of pregnancy the energy requirements of the pregnant mare is the same as those of a mare that is not pregnant.  From nine months onwards the energy requirement increases to support the rapidly growing foetus.  A broodmare can gain 50kg in weight over the last twelve weeks of pregnancy.

During the final month a pregnant mares energy requirement increases to 20% above what it was at 8 months.  The protein and calcium requirements also increase significantly.  A mare needs approximately 1 kilo of protein and 40gm of calcium per day.  This means a 550kg broodmare has to eat 30kg of pasture per day to fulfill her energy requirements.  This amount of pasture while comfortably meeting her protein requirements will only just manage to meet her calcium requirement.  (Spring grass is around 25% protein, and contains approximately 1.4gm calcium/kg).

An intake of 30kg of pasture perday is only possible where there is an abundance of spring growth.  In alot of situations intakes of 30kg per day is not possible, either is just isnt enough grass or the mare is foaling after the spring growth has slowed down.

Lactation places the greatest nutritional demands on a broodmare.  Lactating mares need as much energy in their diets as that of a racehorse in full training.

The amount of energy in the diet influences the amount of milk a mare can produce.  Because foals initially rely on mothers milk as their only source of energy, protein and minerals.  The mares energy intake is therefore a very important factor.  It directly influences how well a foal will grow during the first three months of its life.

A mare in early lactation produces between 15 and 20 litres of milk per day. To be able to do this she needs 70% more energy in her diet than she did at eight months of pregnancy and 40% more than she did during her final month.  Her protein and calcium requirements increase by 50% to 1.5kg and 60gms per day respectively.

A lactating mare needs to consume 45kg of pasture per day (8% of her bodyweight).  Even under ideal grazing conditions, intakes of this magnitude are not possible.  Unless additional energy and mineral sources are fed, the lactating mare will rapidly deplete her body fat reserves and start mobilising calcium and minerals from her bones.

This is even more important when mares foal after the spring growth period and have to graze summer grass while lactating.  Summer grass contains less energy than spring grass, making even less energy available to the mare for milk  production.  Summer grass is also lower in protein  than spring grass and mares will quickly become protein deficient and have to start drawing on body protein reserves.

There are several alternative energy sources that can be used ranging from straight grains through to complete broodmare premixes.  The easiest and cheapest energy source to feed is oats.  Oats have an energy content of 3.0mCal/kg, up to 6kg per day may need to be fed depending on the quality and quantity of pasture available.

A supplementary protein source is necessary if the mare is grazing mature summer grass with minimal new growth.   Lucerne Chaff, soya bean meal and milk powder are all high quality protein sources that can be fed along with the oats.  Alternatively the commercial premixes available for broodmares all contain high quality protein.

Also a good mineral supplement formulated for broodmares should be added to provide additional calcium, phosphorus and trace minerals such as copper, zinc, manganese, iodine and selenium.  These minerals are essential for growth and development of the foals musculo-skeletal system.  The requirement for each of these increases with pregnancy and lactation.

In summary, even if your mare has access to good spring grass she will need extra protein and mineral balances to grow a healthy foal without drawing on her own body reserves.  Make sure you up the feed intake in the last three months of pregnancy and first three months of lactation.