Knowing the normal foal's nursing behavior, hos nutritional needs and his expected growth rate is important in the process of raising healthy young horses.
Within 30 minutes of birth, the foal should exhibit a suckle reflex. You can stimulate this reflex by placing a clean finger in the foals mouth: the tongue should curl around it and the foal start to suckle. Within 1 to 1 1/2 hours, the foals should stand and begin "udder seeking." By 1 1/2 to 3 hrs, the foal should latch onto the udder and begin nursing. A foal that has not stood and nursed within the first 3 hours may be in trouble.
The newborn foal has a very high demand for calories. During the first week, foals may nurse up to 4 times/hour, each time for 1 to 2 minutes. Foals that nurse for longer periods or more frequently might not be getting enough milk. Alternatively, if the mare's udder is still full or hard, the foal may not be suckling enough. Either instance should be called to your veterinarian's attention.
Don't be surprised if your foal eats manure (coprophagia). This normal behavior occurs once every few hours during the first week of life and usually ceases around 3 months of age. The reasons are unknown, but this process may benefit digestion by introducing and supplying essential bacteria to the gut.
Colostrum is stored in the udder for several weeks before foaling, causing the udder to visibly enlarge. Colostrum is rich in antibodies that protect the foal from infections, and it also provide other essentials. Foals are born with little or no antibodies, and this lack of protective antibodies at birth is the reason foals must nurse within 3 hours of birth. If your foal fails to receive or absorb colostrum, his risk for developing a lethal infection is high. If there is any question about your foal receiving adequate colostrum in the first 3 to 12 hours, he should be given proven-quality colostrum or fresh frozen plasma by your veterinarian. If intake is still questionable after 12 hours, your foal should be tested for antibody levels by your veterinarian.
As the foal suckles, the colostrum in the mammary gland is quickly replaced with normal milk. Foals have very little energy reserves at birth. Their energy reserves (glycogen) will support the unfed foal for only 2 to 3 hours. If the foal does not suckle and the energy supply is depleted then the foals will become hypoglycemic (low blood sugar) – the foal appears weak and doesn't suckle well. A common error is to try to supplement weak foals by "syringing" food into the foal's mouth. This should NEVER be undertaken, as it does not provide enough food, and often results in aspiration (inhalation) of milk into the lungs.
Physiology of the Foal's Gastrointestinal System
The foal's small intestine is "open" to absorb the large antibody molecules during the first 12 hours of life. This ability begins to fade and is totally lost at 24 hours of age. Antibodies from colostrum received after this time period will not be absorbed or available to the foal for immunologic protection.
During the first month of life the small intestine grows in length to increase the absorptive surface. Lactase is the predominant digestive enzyme. Lactase is important in breaking down lactose, the predominant sugar in milk. As the foal matures, maltose from increasing grain intake is broken down by a new enzyme, maltase. The large intestine is also growing at this time, an adaptation to a more fibrous diet. Foals should mimic their dams soon after birth by nibbling on solid feed (hay, grass, grain), although they do not derive great benefit from these feed stuffs until the intestines develop.
Mares produce approximately 2 to 3 percent of their body weight in milk each day for the first 3 months of lactation, about 20 to 30 pounds of milk or 10 to 15 quarts per day. Foals ingest 20 to 30 percent of their body weight in milk or 10 to 15 quarts per day.
Foals are usually 1/10th of their dam's weight or their own adult weight at birth. The average daily gains for a light-breed foal are 3.5 pounds (1.6 kg) for the first week of life. They should double their birth weight in the first month of life. Foals grow in height approximately 0.123 to 0.25 inches per day in the first month. They reach 60 percent of their adult height at birth and 95 percent of their adult height by 18 months.