Purdue University
Agricultural Experiment Station
Lafayette, Indiana
Mimeo A. H. 141 January, 1955
HIGH-LEVEL FEEDING OF AUREOMYCIN (CHLORTETRACYCLINE) TO "TAIL-END" PIGS
J. H. Conrad and W. M» Beeson
Department of Animal Husbandry (Progress Report)
Favorable results have been reported when broilers were fed high levels of antibiotics as compared to recommended levels. The greatest advantage of high-level antibiotic feeding has been obtained during periods of stress. This stress may be due to undesirable microorganisms which impair the health and well being of the animal, or it may be due to improper feeding and management practices during certain critical periods in an animal’s life. Pigs that have been subjected to certain undesirable conditions and nutritional stress early in life often become runts or tail-enders.
Tail-end pigs, in general, are animals which do not gain normally when fed according to generally accepted feeding practices and lack the health, vigor and gaining ability of their thrifty littermates. The number of poor doing pigs on farms has been greatly reduced by feeding rations that are adequately fortified with proteins, vitamins, minerals and antibiotics. However, some pigs still fail to gain normally when fed all of the required nutrients at the recommended levels.
An experiment was conducted to obtain information on the response of 40 "tail-end” pigs to high-level antibiotic feeding. These pigs could not be classified strictly as runts since they averaged 30 pounds at 9-10 weeks of age as compared to 4$ pouncfai for their heavier littermates. Prior to the start of this experiment all pigs had received a well-balanced ration containing 20 milligrams of antibiotic per pound.
Experimental Plan
initial to 100 pounds
Forty Duroc weanling pigs were divided into 4 groups of 10 pigs each on the Dasis of age, weight, sex and general appearance. All pigs were 9 to 10 weeks of age. l^elve of these pigs weighed less than 30 pounds but all pigs were considered to be s®all for their age and generally unthrifty.
These pigs were all fed a complete mixed ration which contained a total of 16^ j^ude protein from both plant and animal sources. The basal ration was considered to an adequately fortified growing ration containing no antibiotic. The details of the rations fed are given in Table 1.
The experimental treatments were as follows s
Lot 1 Lot 2 Lot 3 Lot k
No antibiotic 15 grams aureomycin/ton 50 grams aureomycin/ton 100 grams aureomycin/ton
of mixed ration n *	

N
N