Feeding the Broodmare
By NSW Agriculture


Good nutrition and proper exercise will ensure that brood mares remain healthy, conceive early, foal easily and lactate adequately. Feed requirements, however, vary with each stage of the breeding cycle.

Feeding for Conception
Nutrition plays a very important role in reproductive performance, contributing greatly to hormonal output, which regulates the oestrus cycle. Mares should be gaining weight during the joining period. Research has shown a 60% increase in conception rates in mares gaining weight over mares losing weight during this period. It has also been found that embryos in mares on a low plane of nutrition commonly die between the 25th and the 30th day of gestation. These problems can be largely overcome by increasing the mares plane of nutrition 30 to 45 days before the start of the breeding season, and continuing at this level until you are sure she is in foal.

Probably one of the most common problems facing the horse owner is that of the overweight mare. These mares must be allowed to lose weight over the winter period, and should then be placed on an improving plane of nutrition to encourage the onset and regular return of oestrus. This is particularly a problem with maiden mares, which need special treatment.

Mares must have regular exercise to make them fit at breeding time. If kept in a small backyard paddock or a stall, they will need lungeing or some other form of regular exercise to stop them getting too fat. Ideally, keep mares in a large paddock with undulating terrain where they can be encouraged to keep themselves fit. Feeding at some distance from the water supply will encourage movement between feed and water and help maintain fitness.
In general, good quality pasture is sufficient to maintain the mare. Fortunately, the breeding season tends to correspond with the peak of pasture production in spring. However, if supplementary feeding is required it should start well before the horse begins to decline in condition, or at least 30 days before joining.

Gestation
During the first two-thirds of pregnancy the foetus is not very large and the nutrient requirements of the mare are not greatly increased over those for maintenance. Half the growth of the foetus takes place in the last 10 weeks of pregnancy and it is at this time that feed supplements must be increased significantly.

Since foetal growth consists largely of muscle and bone, additional amounts of protein and minerals are needed. These may be provided by increase amounts of good quality pasture. Where this is not available, feed good quality luceme hay or chaff, plus grain. However, the mare should be not too fat just before foaling as this may lead to difficulties during birth.

Table 1: Comparison of the more commonly used Feeds ('as fed')


Lactation
The mare's need for all nutrients almost doubles after she has foaled. These must be provided if the mare is to produce sufficient milk for the foal and gain condition to conceive again.
Lactating mares need about 13 to 14 % crude protein. Pasture cannot usually meet this need, especially when it dries off in late spring and summer. Good quality luceme hay or chaff should again be fed, along with sufficient grain to meet the energy needs of the mare.
Lactating mares in good condition will generally have a short oestrus about 9 days after foaling, but this can vary between 7 and 16 days after foaling. Under favorable conditions, the mare can conceive during this period, saving valuable breeding time, but average conception rates will be only 20 to 25 %. The mare will not return to oestrus again for another for at least another 16 days, but she may take more than 60 days. Good nutrition here is most important to ensure an early and regular return.
Peak Lactation usually occurs 8 to 12 weeks after birth of the foal. This means that, after foaling, mares should receive increasing amounts of feed so that they are steadily gaining weight. Mares of light breeds may produce as much as 24kg milk per day at peak lactation but the average production is probably 14 to 18 kg.

What to Feed
Tables 1 and 2 list average composition of feeds and requirements for dry, pregnant and lactating mares, but should only be used as a guide. Adjustments must be made to meet the individual requirements of the horse.


As a starting point, a ration of equal amounts of roughage and concentrate can be fed to pregnant and lactating mares. The amount to be fed will depend on the availability and quality of the paddock feed, and this can only be determined by gauging each individual's performance on the ration fed.
The type of feed to be given will be determined by the quality of existing paddock feed, bearing in mind that lush spring feed is more likely to be deficient in energy than in protein, and dry summer feed is more likely to be deficient in protein.
As a guide, table 1 gives a comparison of the energy and protein content of some of the more commonly used horse feeds. When used in conjunction with table 2 (which gives the feed requirements for mares of varying weights and status when full hand feeding is required), a balanced ration can be achieved to provide the basis for individual adjustment.