Effects of folic acid and vitamin B12 supplementation on culling rate, diseases, and reproduction in commercial dairy herds

This study was undertaken to determine the effect of a combined folic acid and vitamin B-12 supplement given in early lactation on culling rate, metabolic disorders and other diseases, and reproduction in commercial dairy herds. A total of 805 cows (271 primiparous and 534 multiparous cows) in 15 commercial dairy herds were involved. Every 2 mo from February to December 2010 and within each herd, cows were assigned according to parity, previous 305-d milk production, and calving interval to 5 mL of either (1) saline 0.9% NaCl (control group) or (2) 320 mg of folic acid + 10 mg of vitamin B-12 (vitamin group). Treatments were administered weekly by intramuscular injections starting 3 wk before the expected calving date until 8 wk after parturition. A total of 221 cows were culled before the next dry period. Culling rate was not affected by treatment and was 27.5%; culling rate was greater for multiparous (32.2%) than for primiparous cows (18.8%). Within the first 60 d in milk (DIM), 47 cows were culled, representing 21.3% of total culling, and no treatment effect was noted. Ketosis incidence based on a threshold >= 100 mu mol/L of beta-hydroxybutyrate in milk was 38.3 +/- 2.9% for the vitamin group and 41.8 +/- 3.0% for the control group and was not affected by treatment. The combined supplement of folic acid and vitamin B-12 did not decrease incidence of retained placenta, displaced abomasum, milk fever, metritis, or mastitis. However, the incidence of dystocia decreased by 50% in multiparous cows receiving the vitamin supplement, although no effect was observed in primiparous cows. The first breeding postpartum for multiparous cows occurred 3.8 d earlier with the vitamin supplement compared with controls, whereas no treatment effect was seen for primiparous cows. Days open, first- and second-breeding conception rates, number of breedings per conception, and percentage of cows pregnant at 150 DIM were not affected by treatment. The reduced percentage of dystocia combined with the earlier DIM at first breeding for multiparous cows receiving the combined supplementation in folic acid and vitamin B-12 indicates that the vitamin supplement had a positive effect in older cows.