EFFECTS OF CALCIUM SOAPS OF FATTY-ACIDS ON POSTPARTUM REPRODUCTIVE ACTIVITY IN BEEF-COWS AND GROWTH OF CALVES

Beef cows were used to determine the influence of calcium soaps of fat ty acids (CSFA) incorporated in a range supplement on postpartum repro ductive characteristics and growth of calves. Cows were assigned rando mly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets wer e isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7- d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P <.05; 56.0 vs 50.6 kg, P <.01; 98.8 vs 91.8 kg, P <.01; and 186 vs 173 kg, P <.01, respectively). Body weights at 35 and 50 d pos tcalving were greater in M than in C cows (334 and 310 kg, P <.01; 329 and 300 kg, P <.01, respectively). A similar tendency;Nas observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P <.01 for M and C, Concentrations of total choles terol, lipoprotein cholesterol, low-density lipoprotein cholesterol, v ery-low-density lipoprotein cholesterol, and triglycerides were greate r (P <.01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P <. 02). Percentage of pregnant cows during the first half of the breeding season was greater (P <.02) in M (62.5%) than in C cows (35.5%). We c oncluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calv es.