Sufficient forage should be fed to make up the difference between the horses’ dietary energy needs, as given in Appendix Tables 4, and that provided by the grain mix. This may be done by allowing the growing horse free access to all of the nonlegume forage it will consume. However, if a legume forage such as alfalfa (lucerne) is being used, the amount fed weanlings should be restricted to that needed to provide the amount of digestible energy required for moderate to rapid growth.
The weanling should not be allowed unlimited access to good-quality legume forage. Doing so, just as feeding excess grain, results in excess dietary energy intake, greatly increasing the risk and incidence of developmental orthopedic diseases (DOD) as described in the section on “Feeding Practices that Cause DOD” in Chapter 16. Unless the feed is so low in energy density that the gastrointestinal tract won’t hold a sufficient amount to meet or exceed dietary energy needs of the growing horse, intake of a sufficiently palatable diet will depend upon the energy density of that diet: the higher the diet’s energy density, the less of that diet consumed; the lower its energy density, the more of that diet consumed until the desired amount of energy has been reached. However, the amount of energy desired, or the point at which feed intake stops because adequate energy has been consumed, by weanlings being fed grain or a high-protein, palatable legume forage, is about 20 to 50% higher than the amount of digestible energy needed for a moderate growth rate sufficient to allow the horse to reach its maximum potential size.
A fast growth rate doesn’t increase mature size, but it does increase the risk of developmental orthopedic diseases. This risk is reduced after 1 year of age because growth rate, particularly skeletal growth rate, which is best indicated by height rather than weight, has slowed considerably. As shown in Table 15–2, the horse normally reaches 90% or more of its mature height and, therefore, skeletal size, by 12 months of age. For example, 100% of the cannon bone’s length and 90% of its circumference are reached by 1 year of age. Bone mineral content and strength also increase during growth. Although bone mineral content doesn’t peak until 3 to 4 years of age, most of the increase, like growth, occurs during the first year of life. Yearlings, therefore, in contrast to weanlings, may be given unlimited access to legume as well as nonlegume forages with little risk of causing developmental orthopedic diseases induced by excess dietary energy intake.
In summary, in feeding the growing horse the goal is to achieve a steady growth rate from birth to maturity, avoiding any severe growth depression or spurt by ensuring that all nutrients needed are consumed in the proper amount. This is accomplished by:
TABLE 15–2 Size of Horses from Birth to Maturity as a Percent of Mature Sizea
Example Calculations of Amount to Feed Weanlings
Example 1. For a 4-month-old weanling with an anticipated mature weight of 1100 lbs (500 kg), the amount to feed for rapid growth can be determined in the following manner:
a. (4 mo old) × (1.5 lbs of grain mix/day/mo of age from Table 15–3) = 6 lbs grain mix/day maximum.
b. (6 lbs grain/day) × (0.9 dry matter [DM] content) = 5.4 lbs grain DM/day.
c. (5.4 lbs grain DM/day) × (1.6 Mcal/lb grain DM from Table 15–1) = 8.64 Mcal/day provided by the grain mix.
d. 14.4 Mcal/day needed from Appendix Table 4–500) – (8.64 Mcal/day from grain) = 5.76 Mcal/day needed from forage.
e. (576 Mcal/day needed) ÷ (1.0 Mcal/lb hay DM from Table 15–1) = 5.76 lb hay DM/day needed.
f. (5.76 lbs hay DM/day) ÷ (0.9 DM content) = 6.4 lbs hay as fed/day.
Thus, you should feed 6 lbs (2.7 kg) of grain mix and 6 to 7 lbs (3 kg) of alfalfa hay daily (as compared to 5.5 lbs (2.5 kg) alfalfa/day estimated using the rule of thumb of 0.5 lbs/100 lbs (0.5 kg/100 kg) of anticipated mature weight daily).
TABLE 15–3 Amount of Feed Recommended for Growing Horsesa
Example 2. For a 9-month-old weanling with an anticipated mature weight of 1100 lbs (500 kg), the amount to feed for rapid growth can be determined in the following manner:
a. (9-mo-old) × (1.5 lbs/day/mo of age from Table 15–3) = 13.5 lbs grain-mix/day, but this exceeds the maximum of 0.9 lbs/100 lbs anticipated mature weight daily (Table 15–3), so instead feed (0.9 lbs/ 100 lbs) × (1100 lbs anticipated mature wt), or about 10 lbs of grain mix/day.
b. (10 lbs grain/d) × (0.9 DM content) = 90 lbs grain DM/day.
c. (9 lbs grain DM/d) × (1.6 Mcal/lb grain DM from Table 15–3) = 14.4 Mcal/day provided by grain.
d. (19.3 Mcal/day needed from Appendix Table 4–500) — (14.4 Mcal/day from grain) = 4.9 Mcal/day needed from forage.
e. (4.9 Mcal/d needed) ÷ (1.0 Mcal/lb hay DM from Table 15–1) = 4.9 lb hay DM/day needed.
f. (4.9 lb hay DM/day) ÷ (0.9 DM content) = 5.4 lbs hay as fed/day.
Thus, you should feed 10 lbs of grain mix and 5 to 6 lbs (2.5 kg) of alfalfa hay daily (as compared to 5.5 lbs (2.5 kg) alfalfa/day estimated using the rule of thumb of 0.5 lb/100 lbs (0.5 kg/100 kg) of anticipated mature weight daily).
Feeding Growing Horses on Pasture
Because of the facilities available, or to decrease feeding costs and labor, when adequate pasture forage is available many prefer to keep horses on pasture and to give as little additional feed as necessary. If needed, enough grain mix to allow at least a moderate growth rate (such as given in Appendix Table 4) and to ensure that maximum mature size and skeletal development are not impaired should be fed. For nursing foals, regardless of the forage (pasture or hay) available to them, it is recommended that they be fed the amount of grain mix given in Table 15–3. For weanlings on primarily grass pasture, there should be enough good-quality forage for them to eat all they want. In addition, it is recommended that weanlings be fed daily at least 1 lb (0.45 kg), but not over 1.5 lbs (0.7 kg) of grain mix/ mo of age (for pony breeds, ⅓ to ½ lb [0.15 to 0.25 kg]/ mo of age) up to a maximum of 0.7 to 0.9 lbs/100 lbs (or kg/100 kg) of anticipated mature body weight. However, yearlings or older on good-quality, palatable, growing grass pasture (e.g., Bermuda grass) or winter wheat pasture in early spring, that provide ample amounts of forage even in selectively grazed areas, do not need to be fed any grain or supplemental feed to attain at least a moderate growth rate and their maximum mature size without any detrimental effects. Wheat harvest is not affected by grazing winter wheat early in the Spring (Feb-April in the Central United States).
The amount of pasture forage needed is 60 to greater than 80 lbs of forage dry matter per 100 lbs body wt (or 60 to over 80 kg/100 kg). In a properly fertilized good grass pasture with adequate moisture, this may be obtained with a stocking rate of about 3 yearlings/acre (7 to 8/ha) during the period of forage growth. With lesser amounts of pasture forage available, or poorly palatable forage without supplementation, growth rate will be reduced.
During the winter, or periods when pasture forage is not growing, even when ample amounts of pasture forage are available, at least 5 lbs (2.3 kg) of grain mix daily for light horse breeds must be fed to yearlings or growth and body condition will be reduced.
Cool season annuals, such as wheat, rye and ryegrass pasture providing ample forage, have also been shown to be adequate for yearlings during forage growth (early spring), with little increase in daily gain attained when they were supplemented with a grain mix. In contrast, some pasture forages such as Kleingrass, are not adequate for yearlings even during forage growth, high nutrient content, and with ample quantities available because of poor palatability. Inadequate amounts of a poorly palatable forage will be consumed.
Feeding Nursing Foals
Milk produced by the well-fed normal mare is sufficient to meet all of the foal’s nutritional needs for about the first 2 months of life and all of its mineral needs (calcium, phosphorus, magnesium, potassium, sodium, copper, and zinc) for the first 4 months of life. However, most foals will begin nibbling on the mare’s grain mix and forage within a few days of birth due to imitation behavior, not nutritional need. Most mares will allow their own foals to eat their grain mix (Fig. 15-1) with them, whereas they will frequently drive other foals away. As the foal grows, it will spend progressively more time consuming solid feed, but even at 5 months of age a foal still with its dam will spend only about 50% of its time feeding as compared to 70% for the mare. The amount of solid feed eaten is usually closely associated with the amount of milk being consumed. The more milk, the less solid feed the foal will eat.
Fig. 15–1. Most foals by a few days of age will begin eating the grain mix and hay fed their dam, which most mares will allow their own foal but not others to do.
Past 2 months of age, the amount of milk produced by many mares no longer meets all of the foal’s nutritional needs. Therefore, beginning when the foal is anywhere from 1 to 2 months of age, a grain mix specifically formulated to meet the nursing foal’s needs (Table 4–9) should be fed. Even as young as 3 weeks of age, the foal’s efficiency of grain utilization is high, with the foal gaining about 1 lb/4 lb (1 kg/4 kg) of grain consumed. Feed efficiency decreases as the foal gets older and growth rate slows (to 1 lb gain/7 lbs of grain consumed at 4 months of age). Feeding a grain mix creep feed is beneficial not only in ensuring that the nursing foal’s nutritional needs are met, but also so that following weaning the foal is accustomed to eating a grain mix separate from what it may eat with the mare.
In foals from 1 to 3 months of age, nursing normal milk-producing mares, average daily gain (ADG) up to their maximum genetic potential will be the following:
Lbs/day ADG = 2.08 + 0.109 (Mcal DE from nutritionally adequate solid feed consumed daily), or
Kgr/d ADG = 0.95 + 0.05 (Mcal DE from nutritionally adequate solid feed consumed daily).
Thus, if no grain mix is consumed, the nursing foal will gain about 2.08 lbs (0.95 kg/d). From this formula, it can also be determined how much supplemental feed must be fed to attain a faster growth rate. For example, for 2.6 lbs/ day gain, 4.77 Mcal DE/day of nutritionally adequate solid feed must be consumed, i.e., [(2.6 lbs/d gain — 2.08) ÷ 0.109 = 4.77 Mcal DE/day]. If the grain mix fed provides 1.6 Mcal/Ib, 3 lbs/day would need to be consumed to provide this amount of dietary energy, i.e., 4.77 Mcal DE/day ÷ 1.6 Mcal/lbs of grain mix = 3 lb grain mix/day.
If, during nursing, an adequate amount of nutritionally adequate solid feed is not consumed, then following weaning an adequate diet is consumed, a compensatory growth spurt will occur. This growth spurt greatly increases the risk of the foal incurring and the severity of developmental orthopedic diseases (DOD) (see “Rapid Growth as a Cause of DOD” in Chapter 16). If the foal has been on a good creep-feeding program, this growth spurt, and as a result the risk of DOD, are reduced.
The amount of entirely grain mix creep feed fed should not be restricted until the foals are consuming 4 to 5 lbs (about 2 kg) daily. Prior to this time there should always be feed in the creep feeder. Most foals will eat small amounts frequently. Once the foals are eating 4 to 5 lbs (2 kg) daily, however, the amount of creep feed fed should be limited to that given in Table 15–3 so that growth rate doesn’t exceed that given in Table 15–2. If the amount fed isn’t limited, some foals may eat excessive amounts, resulting in too rapid growth rate increasing the risk and severity of DOD, as described in Chapter 16.
If the mare is fed in a stall, she can be tied and a separate feeder provided for the foal. Alternatively, a stout board can be placed across one corner of the stall in such a manner that the foal can walk under the board easily to get to a creep feed placed in the corner but the mare cannot. For most light breed horses, a height of 54 inches (137 cm) usually is about right. If the mares and foals are on pasture and the foals are fed in a group, care should be taken that all foals can get to a creep feeder without crowding; if not, dominant or greedy-eating foals may consume more than their share, leaving inadequate amounts for less aggressive or slower-eating foals. If this isn’t prevented by having adequate feeding space available, it may be necessary to feed shy, or slow-eating foals separate from aggressive or fast-eating foals. The amount of creep feed needed should be put in the creep feeder in equal amounts at least twice daily after removing any wet or moldy feed that may remain in the feeder.
Creep feeders should be placed close to where the mares are fed, and where there is good drainage, water, salt, shade, or a location attractive to foals, to encourage them to use the feeders. Observations indicate that foals graze only when their mothers do and are more likely to eat, at least initially, and to eat more creep feed, when they see their mothers eating. In addition, they won’t use a feeder if doing so means being too far away from their dam. As shown in Fig. 15-2, there are numerous ways to make the creep feed available to the foal but not the mare. Foals may have to be shown how to enter and eat from a creep feeder. Often confining several foals inside a feeder for a few minutes, showing them the creep feed, and putting some in their mouths to get them started eating it is adequate so they will act as teachers for the remaining foals.
Fig. 15–2(A,B,C). Creep feeders. Figure 15–2 C shows the inside of the creep feeder shown in B. Ensure that the creep feeders are sturdy and safe, and that openings are wide enough and high enough to allow the foal to enter and leave safely while preventing entrance by the mare. Feeders should be large enough to accommodate the necessary number of foals, and covered to keep the feed dry. A feed box containing bars across the top placed close enough together to prevent the mare from inserting her muzzle into the box but far enough apart to allow the foal to eat from the box may also be used as a creep feeder.
Although most foals start eating solid feed in the first few days of life, most receiving adequate milk do not drink water, as the milk meets their water needs. In a study of 15 foals with their dams on pasture, the youngest age at which a foal was observed to drink water was 3 weeks, and 8 of the 15 foals were never observed to drink prior to weaning. However, the foal should always have free access to water, particularly after 3 weeks of age. If a nursing foal drinks very much water (for more than 0.5 to 1 min) or often (more than once daily at an environmental temperature of less than 50°F, or 10°C, or more than every 2 to 4 hrs at 50 to 95°F, or 10 to 35°C), the foal probably isn’t receiving enough milk. This is also indicated by prolonged or excessive bouts of nursing or by a below-normal weight gain (Table 15–2). During the first month of life, the foal normally nurses for 1 to 2 minutes 3 to 7 times/ hr, and light horse breeds should gain 2 to 3 lbs (0.9 to 1.4 kg) daily. The foal’s weight and, therefore, its daily gain can be obtained from a heart girth measurement as described in Chapter 6 under “Obtaining Horse’s Weight’’ or more accurately by weighing the foal. A smaller foal’s weight can be obtained as the difference in a person’s weight holding and not holding the foal when standing on a scale.
Inadequate milk production by the mare is most commonly due to illness or inadequate nutrition. Following a mild or short-term illness, mares will usually return to adequate milk production. However, they usually won’t if the illness is severe or prolonged. If the foal on the mare producing inadequate milk is less than 5 weeks of age, it may be weaned from the mare and all of its milk needs provided as described for “Orphan and Early Weaned Foals’’ later in this chapter. However, if supplementation for no more than a few weeks is likely to be necessary, it may be preferable to leave the foal with the dam and to give it enough supplemental milk so that it drinks little water and gains the normal amount shown in Table 15–2. Some experimentation may be necessary to determine which method works best to get the foal to accept additional milk. If the foal nurses the mare without obtaining milk, hold a nippled bottle near her udder; the foal may start to nurse from the bottle. Some foals may reject a nipple but drink from a bucket. Some may need to be muzzled or periodically separated from the mare before they will nurse a bottle or drink from a bucket.
The total amount of milk needed by normally nursing foals of light horse breeds has been shown to be about 16 qts (or L)/day (20 to 25% their body weight) for the first 5 weeks of life and about 18 qts (or L)/day thereafter (17 to 20% of their body weight). If the foal is over 5 to 8 weeks of age, milk doesn’t need to be given. Instead, the older foal that isn’t receiving adequate milk from its dam may be weaned and fed as a weanling separate from the mare.
TABLE 15–4 Composition of Mare’s and Cow’s Milka
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