Farm Ireland

Wednesday 21 March 2018

Feeding lactating mare correctly vital for its breeding future and young foal

Nia O'Malley

Lactation places immense demands on the mare, both nutritional and physiological. During this time the mare must recover from the stress of parturition, produce milk to support the growth and development of the young foal and re-breed successfully.

In fact, the nutritional needs of a lactating mare are greater than those of any other class of horse, with the possible exception of the racehorse in full training.

If her feed intake is not increased to provide these nutrients, she will maintain milk production by using her body stores for energy, amino acids and minerals, causing loss of weight and loss of body condition as well as mineral losses. If the nutrient deficiency is extreme, milk production and re-breeding efficiency will both decrease.

Mares produce an average of 24lbs (10kg) or approximately 13.5 litres of milk daily during a five-month lactation period. This equates to more than 2,000 litres of milk over 150 days. Some mares can produce as much as 32lbs (15kg) of milk a day. The average amount of milk produced by mares in the first 22 days of lactation is 26.5lbs (12kg) per day. Production appears to reach a peak at 30 days and slowly declines after that.

In order to sustain this output, the protein and energy requirements of the mare almost double from early gestation to lactation. Requirements for calcium, phosphorous, iron, magnesium and vitamin A also increase greatly.

Compared to a performance horse, whose energy needs increase gradually throughout his training, the lactating mare's energy needs increase quite suddenly after foaling. (See Table 1).

In order to meet the mare's requirements during this period immediately post-foaling, it would be advisable to gradually increase her concentrate intake during the last week to 10 days of gestation, so that the mare is consuming close to the amount required for milk production by the time she foals. Suddenly increasing feed intake in the days immediately following foaling could lead to digestive disturbances.

The most-common mistakes made when feeding broodmares are overfeeding during early pregnancy and underfeeding during lactation. A lactating mare will usually consume 2-3pc of her body weight in feed (forage and concentrate) daily.

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However, daily feed intake will depend on the quality of the forage and the energy density of the concentrate. Also, daily feed intake can vary between individuals. Feed intake may have to be increased for hard keepers or heavy milkers, and decreased for mares who are easy keepers.

Peak milk production occurs roughly six-to-12 weeks after foaling. As the mare's milk production decreases, her feed intake should be decreased to maintain proper body weight. At weaning time, reduce the feed further. Gradual feed reduction the week prior to weaning will reduce milk production enabling the mare to dry off quicker.

Energy and Protein

Energy and protein intake can affect the milk production and composition (amino acid and fatty acid profile). A positive energy balance will support reproductive performance and the development and growth of the newborn foal.

Restricted energy or protein intake is known to reduce milk production. Excess energy or protein intake can increase milk production causing foals to ingest too much milk. Excessive milk intake may cause foals to grow too fast, which increases the risk of developing Developmental Orthopedic Disease. A higher milk intake for the foal may also cause digestive upset like colic and scouring.

Mare's milk is very high in protein, typically containing about 20-25pc protein on a dry basis. A mare during peak lactation will secrete over 1lb (0.5kg)/day of protein in her milk. This milk protein is very high in the amino acid lysine, essential for the growth and development of the foal. Lysine helps the body absorb and conserve calcium and helps in the development of collagen and ossification. Meeting the mare's protein requirements through quality protein sources will ensure adequate dietary lysine (see Table 2).


Studies have shown that bone mineral content (BMC) in foals at six months is 68pc complete.

Meeting the mare's requirements for trace minerals (iron, zinc, copper and manganese) is especially critical during the last trimester of gestation, as the foetus accumulates stores of minerals in the liver to support rapid growth post parturition. The foetus has developed this nutritional strategy of storing trace minerals during pregnancy because mare's milk is quite low in these elements. Without proper liver stores of trace minerals, the young foal may be predisposed to bone development disorders.

Research has shown that adding more trace minerals to the lactating mare's diet does not change the composition of her milk. Research has also shown it is not possible to make this up by supplementing the foal with minerals after birth.

Calcium and phosphorus are the minerals of primary concern, and supplementation may be necessary. (See Table 2) Inadequate amounts of these macro minerals in the milk may affect the normal growth and development of the young foal.

Lactation makes the greatest nutritional demands on a mare in any phase of the reproductive cycle. Mares should be fed according to their individual requirements and diet adapted depending on energy requirements, seasonal effects on forage and body condition.

References: Nutrient Requirements of Horses – National Research Council

Nutritional Management of Pregnant and Lactating Mares – B Scott; Feeding the lactating mare – M van den Berg; Protein Needs of Broodmares – J Pagan

Nia O'Malley is an equine nutritionist with Connolly's Red Mills

Irish Independent