Nutritional Considerations For Broodmares
The successfulness of any breeding program depends partially on correct nutritional management of broodmares. Past history reveals the common use of many different nutritional management practices for broodmares. Many of these have contributed to increased cycles per conception, low foaling rates, and below average foal growth. Studies provide information which enables nutritionists to refine recommendations of nutrient requirements for maximum broodmare performance. The broodmare owner should supply the amount and balance of nutrients that will aid in maximum conception rates and best meet the needs during gestation and lactation. Nutrients of concern include energy, protein, minerals and vitamins.
The Open Mare
The mare owner’s objective for this group of mares is high conception rates early
in the breeding season with a low ratio of cycles bred per conception. The sooner
a mare has conceived, the quicker she can be removed from the breeding program, and
the more economical it is to the mare owner. This is especially true when mares are
taken to a breeding farm. Mares that are settled on the first cycle will cost the
owner less in mare care, and better enable the stallion manager to make efficient
use of labor and available stallion semen.
Body Condition and Energy Needs. A major problem with open mares is that many enter into the breeding season in poor
body condition. Body condition is visually identified by observing fat cover along
the neck, withers, back, shoulder, ribs and tailhead (See ANSI-3920 Body Condition
of Horses). Mares in a low body condition have little to no fat cover along the sides
of the neck or withers, behind the shoulder, or around the tailhead. Also, the backbone
and a faint outline of the ribs can be seen. Mares entering into the breeding season
in low condition require more cycles per conception, have lower conception rates,
and are later in their transition into the ovulatory season as compared with open
mares in a fleshy condition. Mares in fleshy condition will have a slight crease down
the back and will have fat covering the outlines of the ribs. Noticeable amounts of
fat can also be seen along the sides of the neck and withers, and the fat deposited
around the tailhead feels soft.
Energy content of the ration is of major concern because of the influence of body
condition on reproductive performance. The amount of energy needed per day will depend
largely on how much the mare weighs, and whether she needs to gain weight before the
breeding season. A 1,200 pound mare maintained in fleshy body condition may meet her
energy needs on an all forage diet. If access to pasture is unavailable and/or hay
is limited, needs could require a high quality grass hay at 1 percent of her body
weight in combination with as much as 6 to 7 pounds of a typically formulated grain
mix daily.
Grain needs for mares on pasture will vary widely due to quality and quantity of available
forage. It is important to observe grouped mares individually as those in low body
condition may need to be removed from the herd and fed supplemental grain. It is important
to remember that mares in a marginal or thin condition can quickly lose condition
when moved to the new surroundings and activities of a breeding farm. Increasing body
condition on these mares prior to moving to the breeding farm will help avoid delays
in the onset of estrous and conception.
Protein needs. The open mare’s protein requirements is no different than for other mature horses
at similar weights. A 1,200-pound mare will need about 1.5 pounds of crude protein
per day. This relates to feeding 15 pounds of a 10 percent crude protein ration. Consider
both hay and grain sources of protein when determining fed levels. It is good practice
to have the hay source analyzed for protein. For example, if 11 pounds of bermudagrass
hay which analyzed to be 10 percent crude protein is fed with 6 pounds of a 12 percent
crude protein grain mix, one would be feeding about 1.8 pounds of crude protein. Usually,
protein requirements are met when feeding adequate grain to maintain energy levels
for a fleshy condition in mature, open mares.
Calcium and Phosphorus Needs. Calcium and phosphorus are the major minerals of concern.
Calcium and phosphorus requirements of open mares are dependent on the body weight
and digestibility of minerals in the feed. A 1,200 pound mare will need about 22 grams
of calcium and 15 grams of phosphorus per day. This level relates to feeding a grain-hay
ration with 0.3 to 0.4 percent calcium and 0.15 to 0.2 percent phosphorus. Calcium
levels should be 1.5 to 2 greater than phosphorus levels in the total ration. Hays
are usually higher in calcium than phosphorus, but levels of available minerals will
vary greatly from different hay crops. Most commercial grain mixes contain equal amounts
of calcium and phosphorus to ensure a proper ratio. Grain mixes should contain a minimum
of 0.5 percent calcium and 0.4 percent phosphorus when combined with grass hays to
ensure adequate amounts of these minerals.
Vitamin Needs. Vitamin requirements are generally met in open mares when feeding high quality grain
and hay. Most commercially available grain mixes have added vitamin sources to ensure
adequate vitamin levels. Vitamin premixes can be fed to supplement questionable feed
sources but should be fed only at recommended Ievels.
Mares in Last 90 Days of Gestation
The mare in late gestation differs nutritionally from the open mare. Her nutrient
requirements are slightly higher because she is maintaining her body and supplying
nutrients to a rapidly growing fetus.
Body Condition and Energy Needs. The mare requires an additional 3 to 4 megacalories of digestible energy above maintenance
requirements. This increased energy need can be met by feeding more of the same grain
mix she was consuming when open and during early gestation. A 1,200-pound mare will
need about two to three pounds of additional grain mix per day when she enters late
gestation to meet her increased energy requirement. Of course this is dependent on
the energy density of the concentrate being fed. It is important that she remain in
fleshy condition if she is to be rebred following foaling. The added nutritional stress
brought on by early lactation can cause mares in a marginal condition to drop in condition
to the point of affecting rebreeding efficiency. Also, many pastures are in their
lowest nutritive value this time of year, so close inspection of mare condition is
necessary so grain and hay levels can be adjusted accordingly.
Protein Needs. The gestating mare has a slightly increased need for protein above her requirement
in the open state. Crude protein requirements will increase about 1/2 of a pound when
mares are in late gestation. This increased need above maintenance is usually met
when feeding more grain mix to supply adequate energy, so a higher percent protein
grain mix is usually not necessary.
Calcium and Phosphorus Needs. As with other nutrients, the amount of calcium and phosphorus required during late
gestation is increased above the amounts needed in the open state. These mares require
approximately 20 more grams of calcium and phosphorus than when in an open state.
As with protein, these amounts are usually more than adequately met when increasing
the amount of grain mix for energy purposes.
Vitamin Needs. The major vitamin of concern during late gestation is vitamin A. Vitamin A requirements
are doubled when mares are in late gestation and lactation. Most commercially prepared
grain mixes have sufficient levels of added vitamin A to adequately meet requirements;
however, many producers routinely feed a vitamin premix to gestating mares consuming
feeds of questionable vitamin levels. It is important that the premix contain about
a 9 to 1 ratio of Vitamin A to Vitamin D, a 6 to 1 ratio of Vitamin D to Vitamin E,
and be fed at levels recommended on the label. Overfeeding of several of the vitamins
can cause irreversible damage to the mare and fetus.
The Lactating Mare
The wet mare’s nutrient requirements are greatly influenced by the amount of milk
produced to supply the nutrient needs of the foal. Milk yields range from two to three
percent of the mare’s body weight per day, so it can be easily seen that nutrient
needs are greatly increased.
Body Condition and Energy Needs. Energy requirements will nearly double following foaling. It is usual for a 1,200-pound
mare to need 12 to 15 pounds of an average energy density grain mix in addition to
10 to 12 pounds of a good quality hay to meet her energy needs. Mares will also typically
increase their voluntary intake during lactation and also meet a great percentage
of their energy intake with high quality forage if allowed, thus reducing the total
amount of concentrate needed. Careful management is necessary in this class of mares
because individual requirements will vary greatly. A foal can quickly lower condition
in the mare, and wet mares in a thin body condition may take longer to rebreed and
have lower pregnancy rates than mares in a moderate to fleshy condition. Also, the
mare may be moved to a new location for breeding soon after foaling, which can create
a loss in condition due to stress. It is extremely difficult to increase condition
in lactating mares because the amount of feed that would be necessary can lead to
higher incidence of founder and colic. As such, it is important that the mare is adequately
conditioned before foaling.
Protein Needs. Protein requirements are also of importance during lactation because of the large
amounts of protein leaving the mare in the milk. Mares not receiving adequate protein
have decreased milk production resulting in lowered foal growth. Requirements double
in heavily lactating mares, and an increased percent protein ration is usually necessary.
Most hay-grain combinations dictate that the grain mix be at least 14 percent crude
protein. Grain mixes with 10 to 12 percent crude protein should be fed with a hay
high in crude protein, so many producers feed a high quality alfalfa with this type
of grain mix.
Calcium and Phosphorus Needs. Calcium and phosphorus needs will also double in the lactating mare as compared with
her requirements for maintenance. The calcium and phosphorus density of the grain
ration will depend on the amount of grain and hay that is fed. The mineral density
of most rations should be increased to levels of 0.6 percent calcium and 0.4 percent
phosphorus to meet the added requirement. Mineral needs can be met when increasing
the amount of grain mix fed for energy needs. If grain and hay sources are marginal
in their mineral densities, it is advisable to add a mineral premix to rations for
this class of mares. Mineral premixes, like vitamin premixes, should be added only
at recommended levels.
Vitamin Needs. Most classes of horses will meet their vitamin needs by feeding high quality grains
and hays. Vitamin requirements increase in lactation to the point that it is a good
practice to add a vitamin source to grain mixes. Feed suppliers and feed tags should
provide information on whether grain mixes have been fortified with vitamins during
the feed manufacturing process. If not, it is recommended to add a vitamin supplement
on-site to the grain mixes for lactating mares. Vitamin premixes should contain about
a 9 to 1 ratio of Vitamin A to Vitamin D, and about a 3 to 1 ratio of Vitamin D to
Vitamin E, and be fed at levels recommended from label directions to ensure proper
levels of these vitamins. Regardless, it is always important to fully consider the
composition of the diet before adding additional supplements and consultation with
someone educated in equine nutrition is always justified.
Extension Equine Specialist