Mineral Intake in Nursing Foals

Many of the minerals needed by the newborn foal for the first month or so of life are actually given to the foal by the mare in utero before it even starts nursing, which is why proper attention to the diet of the mare in the third trimester of pregnancy is important. Ideally, from then on foals initially derive all of the nutrients necessary for growth and development from the mare’s milk and forage. If they don’t get the nutrients from the mare then during the first few months of life, foals will be solely dependent upon what is in the milk and grass. As foals continue to nurse and then begin to graze and share the mare’s grain, they will ingest whatever is needed to continue a smooth growth plane and achieve optimal size at maturity. Due to variations in mare nutrition, soil composition, forage types, weather, and health status, not all foals stay on this ideal growth path.

Pasture soils vary, so the quantity of minerals obtained from forage and milk may not be sufficient to meet a foal’s requirement for these nutrients. Deciding when to provide foals with creep feed and the appropriate composition of this feed becomes critical. The objective of a study conducted by the Japan Racing Association was to measure the amount of mineral intake from milk and pasture and to analyze the appropriate nutritional management of a nursing foal.

Researchers used eight Thoroughbred mares and foals to study milk consumption and mineral intake from milk. They measured the amount of daily milk consumption by the weight-suck-weight method at 3 days and then at 1, 3, 7, 10, and 17 weeks of age. Milk samples were taken by hand at the same time each day, and calcium, phosphorus, magnesium, zinc, and copper intakes from milk were measured. The amount of daily milk consumption decreased with age after the foal reached three weeks, and intake of minerals from milk also decreased significantly.

The researchers estimated daily pasture consumption for five foals, collected all feces excreted in a day, and analyzed lignin in feces and pasture. Daily intakes of calcium, phosphorus, magnesium, zinc, and copper from pasture increased from 3 days to 17 weeks of age.

Total mineral intake from milk and pasture was judged to be inadequate between one and three weeks of age for foals in this study. These results suggest that concern for proper mare nutrition in the third trimester is paramount since the mineral nutrition from the milk and forage will not be adequate.