Purdue University
Agricultural Experiment Station
Lafayette, Indiana
Mimeo AH - 142 April 29, 1955
EFFECT OF ANTIBIOTICS ON CATTLE FATTENED ON CORN SILAGE OR GRASS SILAGE
W. M. Beeson, M. T. Mohler and T. W. Perry Department of Animal Husbandry
Previous research (AH Mimeos 120,130) has shown that feeding 75 milligrams of antibiotic, such as aureomycin or terramycin, per steer daily will improve growth rate and feed efficiency on high roughage rations or when a limited amount of corn is fed. But on high corn diets, supplementing with antibiotic has not given any significant improvement at the 75-milligram level. A slight improvement was obtained in fattening rations by feeding 200 milligrams of aureomycin per steer daily. The acceptance and general use of antibiotics in cattle rations is still in the experimental stage. To date response from antibiotic feeding has not been consistent and more research needs to be conducted before the final answers are known.
This experiment was designed to determine the effect of feeding 75 milligrams of aureomycin per steer daily on a ration of (1) corn silage and Supplement A and (2) grass silage, Supplement A and corn.
Experimental Plans
One hundred and fifty yearling Hereford steers, which were raised in Colorado, were purchased at an average price of $22.50 per hundredweight and delivered to Lafayette, Indiana. The average purchase weight was 700 pounds. Forty of these steers averaging about 750 pounds vere used for this experiment. The steers were equally divided according to weight, type and general thriftiness into four lots of 10 steers each.
Method of Feeding
Corn silage and grass silage were hand fed twice daily according to the appetite of the steers. Half of the supplement and/or ground shelled corn was scattered over the silage at the morning and evening feed and thoroughly mixed with a silage fork in the feed bunk. Aureomycin was mixed in Supplement A at a level of 37• 5 milligrams per pound or 75 grams per ton. Two pounds of Supplement A supplied 75 milligrams of aureo-mycin per steer daily.
Description of Silages
^orn Silage;
The corn silage was harvested with a field ensilage chopper and blown into an up-right silo when the kernels were dented and some of the leaves were still green. The yield was 10 tons of silage per acre and 60 bushels of corn. Figuring corn at $1*40 Per bushel and the cost of ensiling at $3 per ton, the corn equivalent cost of silage vas $10.40 per ton.
ms3 Silacrp*
The grass silage (3/4 alfalfa and l/4 red clover) was chopped directly from the *ield (no wilting) and blown into an upright silo with the addition of 150 pounds of “Orn-and-cob meal and 100 pounds of ground cobs per ton. Corn-and-cob meal was added as a preservative and the extra cobs to absorb the excessive moisture. This method Prevents the silage from seeping and losing valuable nutrients by excessive runoff.
^ anc* seven-tenths tons of grass (legume) silage were produced per acre at a harming and ensiling cost of $3.50 per ton. The cost of silage (including corn and s added) on a hay equivalent basis was $11.60 per ton.