Raising a healthy foal involves closely monitoring their growth. This will help you make appropriate changes to their diet and management to support optimal development.

Foals grow quickly in the first few months after birth, reaching ~80% of their mature height and ~43% of their mature weight by just six months of age. This rapid growth rate makes foals susceptible to developmental and joint issues, which can impact their future well-being and performance in the long-term. [1]

Throughout the first year of life, it is critical to meet your foal’s protein, vitamin, and mineral needs without exceeding calorie requirements. Over-feeding increases the risk of developmental orthopedic diseases (DODs).

In the first couple of months, the mare’s milk is usually sufficient to meet a foal’s energy and protein needs. Properly feeding the lactating mare will ensure she produces enough healthful milk for the foal. [2]

Although foals begin nibbling at feed and forages as early as one week old, they generally do not need to eat feed and forages until two or three months of age. After six months, your foal’s diet will largely consist of forages and concentrates to continue to support their growth. [2]

This article will discuss growth patterns in foals, creep feeding, how to adjust their diet as they grow from weanling to yearling, and nutritional requirements at different ages.

Disclaimer: Raising a healthy foal requires working closely with your veterinarian and equine nutritionist. The hay and pasture composition used in the sample diets may be very different from your situation. Submit your foal’s diet to consult with our nutritionists throughout their early life.

 

Foal Growth & Development

One of the most important factors to consider when feeding foals is their growth rate. Foals that are growing slowly may need more energy in the diet from higher quality hay or other energy-dense options, whereas fast-growing horses may need restricted access to feed.

Another reason to pay close attention to the foal’s growth over time is to support joint health. Fast growth has been linked to joint issues in growing horses and developmental orthopedic diseases (DODs) including physitis and Osteochondrosis dissecans (OCD). [1]

Factors Affecting Development

A foal’s potential mature body weight and conformation are largely determined by genetics or breed. [3][4]

How fast they develop and whether they develop to their genetic potential is affected by many factors, including nutrient availability, environmental factors, and management.

Nutrient Availability:

  • Feeding program
  • Month and season of birth
  • Pasture quality and availability
  • Gestational nutrition and health of the mare
  • Colostrum and milk intake

Environmental and Management Factors:

  • Freedom of movement and exercise level
  • Ambient temperature
  • Weaning and associated stress
  • Health history
  • Parasitism
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Mare Nutrition

Horses evolved with seasonal estrus so that the end of gestation and beginning of lactation aligns with the presence of fast-growing, energy-dense spring grasses.

This helps ensure that mares are meeting their energy and protein needs when they are at their peak. The mare can produce large volumes of milk with abundant pasture, and the foal will have high-quality forage to graze. [5]

Weight gain is the fastest in early life. The mare’s nutrition largely impacts this period of growth during gestation and also affects the mare’s milk production. [5][6]

Measuring Foal Growth

To appropriately balance your foal’s diet, it is important to regularly measure and record their weight. Because large animal scales are not widely available, you can use a weight tape to measure their girth and apply the following calculation: [7]

Body weight (kg) = Girth3 x 90

The calculated value can be compared to estimates of their current weight, as shown in the table below.

Growth of a foal predicted to weigh 500 kg / 1,100 lb as an adult

Age Growth Rate
(kg / day)
Estimated Weight % of Mature Weight
4 months 0.84 169 kg / 373 lb 34
6 months 0.72 216 kg / 476 lb 43
9 months 0.57 275 kg / 604 lb 55
12 months 0.45 321 kg / 708 lb 64
18 months 0.29 388 kg / 855 lb 77
24 months 0.18 429 kg / 946 lb 86
36 months 0.07 472 kg / 1041 lb 94

 

The calculation used to provide the estimated weight is as follows, where M is the predicted mature body weight (kg) and A is age in months: [3]

Estimated Body weight (kg) = M x (9.7 + (90.3 x (1-e-0.0772A)))/100

Comparing your foal’s ideal weight to their actual weight as measured with a scale or weight tape can help you determine if your foal is on the right track. Ideally, measurements should be taken frequently to monitor their overall growth pattern rather than looking at a single measurement.

You can also calculate your foal’s average daily gain (kg) with the following equation, where M is the predicted mature body weight (kg) and A is your foal’s age in months: [3]

ADG (kg) = M x 6.97 x (e(-0.0772xA))/3040

Growth Patterns

Foals will naturally go through periods of slower growth followed by growth spurts during the first 1.5 – 2 years of life.

Although fast growth may be desirable for getting a better price at sales, aiming for fast growth can be detrimental, particularly for joint and metabolic health. [1][8]

Slow Growth

Consult with your veterinarian and equine nutritionist if you observe long periods of slow growth. Slow growth may be due to the following:

  • Genetic disorders
  • Growth abnormalities
  • Illness or injury
  • Nutritional deficits
  • Nutritional imbalances

Your veterinarian will also determine appropriate vaccination and deworming programs to help your foal avoid diseases caused by common pathogens.

Weight Gain

The season and month of the year when your foal is born significantly impact their growth rate. Studies in the Northern Hemisphere show that foals born in January have different growth patterns than those born in May. [5][9]

Daily weight gain is lowest in the first winter when more calories are burned to maintain body temperature.

Following this period of slow growth, most foals experience a growth spurt the next spring and summer. This is referred to as compensatory growth or catch-up growth.

Erratic growth patterns are possibly linked to DODs, and aiming for a smooth growth curve through the winter and spring is preferred. Your foal may require more feed through the winter and restricted pasture access in the spring to regulate growth. [5]

Height Gain

The foal experiences the fastest height gain in early life, and the growth rate decreases over time. For example, Thoroughbred foals have reached 80% of their adult height by six months. [1]

Breed Differences

Growth curves and the above growth calculations are based on observational studies that measure the growth of thousands of foals over time. To date, this research has mostly involved Thoroughbred foals. [5]