GESTATION AND LACTATION OF DAIRY-COWS - A ROLE FOR FOLIC-ACID

Twenty-four multiparous and 16 primiparous dairy cows were assigned by parity, BW, and milk production to 20 blocks of 2 cows each. Within e ach block, the cows were injected weekly with either 0 or 160 mg of fo lic acid from 45 d after mating to 6 wk after parturition. Supplementa ry folic acid augmented the placental and colostral transfer of folate s to the calf but had no effect on blood hemoglobin, birth weight, or growth and feed intake of the calf during the first 10 wk of life. The supplemental folic acid increased serum folates but had no marked eff ect on blood hemoglobin and BW of cows. Supplementary folic acid tende d to increase milk folates, milk production, and the percentage of mil k protein during the last half of the lactation curve but had no effec t on milk folates and milk production during the first 6 wk after part urition when the injections of folic acid increased the percentage of milk protein in multiparous cows but had no effect on primiparous cows . The supply of folates by the diet and the synthesis by ruminal micro flora is sufficient to prevent folic acid deficiency in dairy cows and to maintain normal gestation and lactation, but not to achieve maxima l production of milk and protein in multiparous dairy cows during gest ation and lactation.