Folate nutrition in the kid.

I. A study was made on the folate content of goat’s milk in relation to stage of lactation, and on the interrelationship between blood and milk folate concentrations in the dam and in the kid. 2. In seven goats the folate concentration in the colostrum at parturition ranged from 136 to 300 ng/ml, and averaged 205 ng/ml. The concentration fell sharply during the early days of lactation and by day 14 it averaged only 9-5 nglml. This pattern of rapid decline in milk folate concentration with advancing lactation was little affected by daily provision of folic acid parenterally in relatively large amounts. 3. The colostrum and milk contained a minor whey protein that combined strongly with folate, and presumably acts as a trapping mechanism to accumulate the vitamin from the plasma into the milk. The milk folate concentration is determined by the rate of milk secretion in relation to the availability of free folate in the blood plasma. 4. At parturition the plasma folate concentration in the kids was very low about I nglml but by day 2 it had increased to about 28 ng/ml. This folate was protein-bound and accompanied by an excess of free binder protein. It appeared that the folate-protein complex from the colostrum was transmitted intact into the kids’ blood circulation. 5 . The possible importance of the folate-binding protein in the regulation of folate metabolism is discussed.