The Mode of Action of Antibiotics in Stimulating Growth of Chicks

Abstract

A study was made of the effect of antibiotics on growth of chicks and on intestinal absorption of fats and carbohydrates. Around the 8th day of life, chicks fed an antibiotic-free casein-sucrose diet developed a transitory syndrome of malabsorption of fats and carbohydrates, associated with disturbance of the efficiency of feed utilization and poor weight increase. Administration of virginiamycin, at a level of 20 ppm, suppressed this period of malabsorption and resulted in improved feed conversion and increased weight gain. The temporary growth depression and malabsorption were not observed in disinfected rooms in new quarters. Under these conditions virginiamycin did not stimulate growth nor was the efficiency of feed utilization improved by the antibiotic. However, the growth-depressing flora could be introduced to the new quarters by feeding each bird 50 mg of fresh feces collected from chicks in old quarters. Both the intestinal absorption and the growth-promoting effect of virginiamycin were influenced by the type of carbohydrate in the basal diet, and have been found to be most pronounced when sucrose was fed as the sole source of carbohydrate. The malabsorption was less obvious when cornstarch was substituted for sucrose. In this case virginiamycin had only a limited effect on growth and on feed conversion. The present investigations suggest that antibiotics stimulate growth of chicks by their antibacterial action against Gram-positive microorganisms which interfere with the absorption of nutrients. Furthermore, the growth-promoting effect seems to be most pronounced during a limited period of a few days around the 8th day of life.

Effect of Antibiotics on Growth and Nutrient Absorption of Chicks

“…In animals given an antibiotic-free diet these microorganisms could provoke a polymalabsorption syndrome including not only vitamins and minerals but also proteins, fats and carbohydrates. Our previous work with the antibiotic virginiamycin supported this hypothesis (Eyssen and De Somer, 1963).…”

“…I N A recent study from this laboratory, on the mode of action of antibiotics as growth stimulants for young animals, a transitory period of growth depression was observed around the 8th day of life in chicks fed an antibiotic-free, caseinsucrose diet (Eyssen and De Somer, 1963). The inhibition of weight gain was found to be associated with decreased efficiency of feed utilization and malabsorption of fats and carbohydrates, and the syndrome was most pronounced when sucrose was fed as the sole source of dietary carbohydrate.…”

Probiotic Bile Salt Hydrolase: Current Developments and Perspectives

“…Microbial deconjugation and dehydroxylation of conjugated bile salts by BSH-positive bacteria upset the digestion process, which results in related complications and abnormal growth. A product of microbial bile acid biotransformation in host intestine was found to be the main cause of growth reduction in chicks [96]. Microbial deconjugation and dehydroxylation of bile acids also mess up lipid assimilation in the host [97,98]; moreover, it produces toxic products to facilitate the impaired growth [99].…”

Effect of the anticoccidial agents halofuginone and monensin when given with growth promoting antibiotics upon the control of coccidiosis in the turkey

“…The growth rate of turkeys medicated with HAL or MON is significantly improved by supplementation with BAM or BAC (Waldroup et al, 1985(Waldroup et al, , 1993. These antibiotics are thought to stimulate growth by their antibacterial action against gram-positive microorganisms which interfere with the absorption of nutrients (Eyssen & Somer, 1963). No cross-resistance has been found between strains of bacteria resistant to BAM and bacitracin (Wasielewski et al, 1966), probably because both drugs inhibit bacterial cell wall synthesis although by different mechanisms (Gale et al, 1972).…”