Suckling a foal, or lactation, is a period of significant physiological stress for mares. The nutrient needs of the lactating mare are greater than any other horse, except perhaps a racehorse in peak training.
Add to this a possible new pregnancy as lactating mares are rebred and the likely effects of nutritional stress become abundantly clear.
The lactating mare has increased requirements for many nutrients and a deficiency in any minerals, for example, will result in the mare to use up her own stores, causing possible deficiencies in the mare and foal and problems with rebreeding.
It is vital to keep mares in good condition prior to foaling and through lactation.
Research has shown that underfeeding a mare could extend gestation by up to 10 days. In addition, mares with a condition score (CS) of 5 or greater have better fertility for rebreeding.
The energy status of mares is therefore important for breeding.
Mares going into the breeding season in a moderate body condition (CS 5/6) required fewer cycles for conception and had higher conception rates than thinner mares (CS 4 or less). Mares who foal down in thin condition tend to remain thin through lactation and have a longer period from birth to the second oestrus period.
Mares in better condition also ovulated sooner than mares with a CS of less than 5.
It also appears that keeping mares at a higher CS of 7/8 did not impair or improve reproductive performance.
A 550kg lactating mare may produce an astonishing 11-14kg milk per day for the first three months of her foal's life.
This amount will decrease to about 8kg/day by five months. This equates to about 450ga over a 150-day period.
This is obviously a huge metabolic effort by the mare and graphically explains the importance of meeting her nutrient requirements during this time.
A mare's milk is also rich in protein and fat and therefore the her diet must also have more protein and energy to meet these increased needs.
It is important to choose a good quality concentrate stud feed/balancer from a reputable manufacturer, as well-balanced nutrient formulations will contain higher levels of nutrients in their most bio-available forms.
For example, different carriers of the same mineral can be absorbed and used at significantly different levels.
Some forms of minerals are more easily used within the mare's body than others, while others are very poorly absorbed.
When lactating mares are fed concentrates based upon fat/oil and fibre (low starch rations), as compared to higher starch-based concentrates such as stud mixes, milk composition is affected in ways that help to improve the health of suckling foals.
Levels of the essential fatty acid, alpha-linolenic acid (ALA) in milk are increased and this in turn may lead to a reduction in gastric ulcers in foals. Higher colostrum levels of IgG are also found and colostrum is vital for immunity of the foal.
Mares fed on fibre- and fat-based diets should also be given a good low-starch stud balancer that contains all the quality amino acids, vitamins and minerals needed to meet requirements.
A good choice of oil is linseed or flaxseed oil. Linseed oil is the same as common flaxseed oil (Linum usitatissimum) and is a rich source of ALA, which is also thought to be beneficial for fertility.
Lactation typically lasts about six months due to varying management factors such as time of weaning. During the first three months of lactation, mares certainly need individual attention.
Overweight or 'good-doers' will need a different approach to feeding than the underweight mare. Some mares sail through lactation with little -- if any -- loss of condition, whereas others may lose a significant amount of weight.
If mares lose weight during early lactation or mares are underweight at foaling, then the time for rebreeding may be lengthened and conception rates may be lower, as discussed earlier. These mares may need a higher-energy stud cube, preferably with lower starch levels than a stud coarse or cereal mix.
Oil and fibre may not provide enough calories for some of these mares, during early lactation particularly where pasture or forage quality/quantity is not sufficient.
On the other hand, most lactating mares will hold their condition well on top quality forage/pasture and a low-calorie stud balancer only.
The levels of all nutrients required increases in early lactation. All these will be provided if the chosen stud feed is fed at the recommended quantities. If not, then nutrient intake may be compromised. If the correct levels of formulated stud feed are being fed, there is absolutely no need for an additional pasture mineral block.
It goes without saying that all lactating mares will drink large amounts of water, and clean, fresh water must be available to them at all times. A free choice salt lick is also beneficial.
Pasture should be analysed to look for any mineral deficiencies.
Over the past three months of lactation, daily requirements start to decline significantly. Although the volume of milk remains much the same, the nutrient density, particularly energy, decreases substantially.
By month four, the mare's milk will provide less than 30pc of the total energy needs of the foal, which should now be eating well on its own.
Concentrates can therefore be reduced by 50pc at around three months. Foals should be eating well, ideally a low-starch balanced creep feed or balancer in readiness for weaning.
Research showed that lactating mares were less stressed at weaning when fed an oil and fibre-based diet compared to high cereal starch feeds. It makes sense, therefore, to prepare mares for weaning by feeding plenty of top quality forage, with alfalfa/beet pulp and oil with a stud balancer supplying vitamins, minerals and quality amino acids.
Throughout lactation, the mare's bodyweight should be monitored closely and minor adjustments be made to the concentrate ration as and when required to ensure the mare remains in optimum condition.
This will help mares maintain their health and breeding performance.