Nutrition in the Newborn Foal
Dr. Mary Rose Paradis
In general, the dam takes care of the nutritional needs of the newborn foal. She provides the foal with the essential colostrum (the first milk that the mare makes) in the first few hours of life, which provides him with protective antibodies, and with the necessary nutrients through the next 4 to 6 months to support the foal's growth and well being. Knowing the normal foal's nursing behavior, his nutritional needs, and his expected growth rate, is important in the process of raising healthy young horses.
Within 30 minutes of birth the normal foal should exhibit a suckle reflex. You can demonstrate this by placing your finger in the foal's mouth and seeing if the foal reflexively curls his tongue around it. You may also see the foal trying to suck on your clothing, different parts of the mare or on the wall. Within 60 to 90 minutes the foals should stand and begin udder seeking. By 90 to 180 minutes the foal should have found the udder and received his first feeding. These time parameters are very important deadlines to meet. A foal that has not stood and nursed by 180 minutes needs veterinary assistance.
The newborn foal has a very high metabolic rate. The high metabolic needs of the foal require that the foal nurse frequently. During the first week of life, foals may nurse up to four times/hour for an average of 1 to 2 minutes per nursing bout. Foals noted to nurse for longer periods or more frequently might indicate that the mare is not making sufficient milk to satisfy him. Likewise, an engorged udder may indicate that the foal is not nursing enough, a sign that the foal may be sick.
Coprophagia (eating manure) is normal in the newborn foal. This 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 some people feel that it is an important process in inoculation of the gut with beneficial bacteria.
Colostrum is the specialized mammary secretion that is produced by the mare during the last few weeks of gestation and stored in the udder. It differs from milk in that it has a higher specific gravity; it is higher in total solids, gross energy, vitamin A and E and five times higher in protein. The most important components of colostrum are the maternal antibodies (immunoglobulins), predominantly IgG but also IgA, IgE, and IgM. Other important immunoprotective elements in colostrum include complement, transferrin and lactoferrin. Foals, as well as many other domestic species, are born with little to no circulating antibodies. In humans, antibodies pass from the mother to the fetus through the placental membranes, in utero. Due to differences in the equine placenta, no antibodies can pass from the maternal blood stream to the fetal blood stream in the horse.
This lack of antibodies is one of the reasons it is crucial for the newborn foal to nurse within 3 hours of birth. Foals are not born into a sterile environment and they are exposed to potentially lethal bacteria from the moment that they exit the uterus. It literally becomes a race between the absorption of protective antibodies and the exposure to bacteria. If the foal fails to receive or absorb colostrum, this is called failure of passive transfer of maternal antibodies or FPT. This foal is a higher risk to develop infection.
The mare only makes colostrum once with each pregnancy. As the foal suckles, the colostrum in the mammary gland is quickly replaced with normal milk. Certain mares will drip colostrum prior to the birth process (parturition). If they drip enough to deplete the supply of colostrum, the foal may nurse within the time limit and still not receive adequate antibodies because the colostrum has been replaced by milk, which is very low in antibodies. These foals should be labeled "high risk" foals and should receive good colostrum from another mare or a plasma transfusion that contains antibodies. Antibody levels in the foals can be checked with a simple blood analysis after 12 hours of age. It is crucial to have your foal tested if there is any question about colostral intake. Do not "wait and see" or hesitate to call your veterinarian about testing your foal. This is a most serious mistake, and can cause death of the foal.
Foals have very little reserves in energy at birth. Their glycogen (energy) reserves will support metabolism in the absence of feeding for only 2 to 3 hours, thus another reason for early consumption of colostrum. If the foal does not suckle and their energy supply is depleted then the foals will become hypoglycemic (low blood sugar). Hypoglycemic foals are lethargic and weak, further compromising their ability to nurse. Energy supplies from colostrum ingestion alone lasts for 17 to 19 hours.
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 and width, presumably to increase the digestion and absorptive area. Lactase is the predominant disaccharidase (enzyme) at this time. This is important since lactose is the main sugar in found in mare's milk and lactase is important in breaking down this sugar so that the foal can absorb the nutrients. As the foal matures the predominant enzyme in the intestine becomes maltase, the enzyme that breaks down maltose, the more common sugar found in grains. This change is coincidental with the increase reliance of the foal on grain as they mature.
The large intestine is also growing at this time as it begins to adapt to a more fibrous diet. Foals mimic their dams soon after birth by nibbling on solid feed and grass but they do not receive many nutrients from this feed until the large intestinal adaptation occurs.
Light breed mares produce approximately 2 to 3 percent of their body weight in milk/day for the first 3 months of lactation. A 1,000-pound mare would produce 20 to 30 pounds of milk or approximately 10 to 15 quarts per day. At the same time, normal foals ingest 20 to 30 percent of their body weight in milk or 10 to 15 quarts per day.
Foals are generally 10 to 11 percent of their dam's weight or their own adult weight at birth. For example a mare weighing 1,000 pounds normally will produce a foal that ranges in weight from 100 to 110 pounds. The average daily gains for a normal foal are 3.5 pounds or 1.6 kilograms for the first week of life. They should double their birth weight in the first month of life. Daily weight gain is a good prognostic indicator of health. Sick foals will not gain weight until the illness is under control.
The normal foal grows in height approximately 0.123 to 0.25 inches /day in the first month of life. They are roughly 60 percent of their adult height at birth and reach 95 percent of their adult height by 18 months of age. This may differ in the large breeds that are slower to mature.