Purdue University
Agricultural Experiment Station
Lafayette, Indiana
High Levels of Antibiotics for "Tail-End" Pigs — A Study of Levels and Sources
W. M. Beeson and J. H. Conrad
Department of Animal Husbandry
Mimeo. A.H. 158 September 16, 1955
Favorable results have been reported when broilers were fed high levels of antibiotics during periods of stress. It is reasonable to believe that young pigs which have been subjected to certain stress factors may respond also to high levels of antibiotics o 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 these factors at the recommended levels.
Two experiments have been conducted to study the effects of adding different levels and sources of antibiotics to growing rations for ''tail-end" pigs.
Experiment Plan
Experiment L
Forty Duroc weanling pigs 9 to 10 weeks of age, which averaged 30 pounds, were used in this experiment. During the suckling period, these pigs had been receiving a well-balanced creep ration containing 20 milligrams of antibiotic per pound.- However, these pigs were not growing as well as their heavier littermates, which averaged 45 pounds at 9 to 10 weeks of age. All pigs used in this experiment were considered small for their age and generally unthrifty. They were divided into 4 lots of 10 pigs each and were fed according to the following experimental treatments:
Lot 1	No	antibiotic
Lot 2	15	grams	aureomycin/ton	of	mixed	ration
Lot 3	50	grams	aureomycin/ton	of	mixed	ration
Lot 4	100	grams	aureomycin/ton	of	mixed	ration
Details of the rations fed are given in Table 1.
After the pigs fed the 50 and ICO gram levels (Lots 3 and 4) reached ICO pounds, the level of antibiotic was reduced to 15 grams of antibiotic per ton. All pigs received a 16% protein ration to ICO pounds and a 12.5$ protein ration from ICO pounds to 2C0 pounds .
A summary of the results of Experiment 1 are given in Table 2. pmeriment II
Eighty-four Duroc weanling pigs, 9 to 11 weeks of age and averaging 29 pounds,were Used in this experiment. These were the tail-end pigs from 7C0 pigs that were weaned :rcm the spring farrow. These pigs had received a variety of creep feeds prior to wearing both in drylot and on pasture. They were divided into 7 lots of 12 pigs on the basis uf previous treatment, age, weight, sex and general appearance. Pigs in the different -ots were fed according to following experimental treatments: