COMPARISON OF SILAGES MADE FROM GRASS, GRASS-LEGUME AND CORN FED TO STEERS WITH AND WITHOUT DIETHYLSTILBESTROL

Abstract

Three silage crops were evaluated as the major source of nutrients for finishing beef steers in terms of the efficiency of animal gain per unit weight of crop harvested and per unit of land used to grow the crops. Silage was made from (1) grass −65% timothy (Phleum pratense L.); 10% couch grass (Agropyron repens L.), 10% bluegrass (Poa pratensis L.), 15% brown top (Agrostis sp.); (2) grass–legume −50% bromegrass (Bromus inermis Leyss), 50% alfalfa (Medicago sativa L.); and (3) corn (Zea mays L.). The three silages were fed to yearling Hereford steers for a period of 126 days. In addition to silage, all steers received 1 kg of coarse ground barley per head per day and one-half of those fed each silage received, in addition, 10 mg of diethylstilbestrol (DES) mixed in the barley. Dry matter percentage at harvest was 25.8 for grass, 18.4 for grass–legume and 24.1 for corn, resulting in a loss from seepage, respiration and fermentation during storage of 9.5, 15.3 and 0.1%, respectively. The average daily gain (ADG) for steers fed corn was 1.05 kg; for grass–legume, 0.89 kg and for grass, 0.56 kg. When DES was added the ADG increased to 1.15, 0.96 and 0.74 kg, respectively. The calculated animal gains per hectare of each crop were 695, 1,414 and 1,415 kg for grass, grass–legume and corn, respectively. Higher grades of carcasses were obtained from steers fed corn silage than steers fed grass–legume silage which in turn were better than those from steers fed grass silage.