A comparision of the growth of chicks in the Gustafsson germ-free apparatus and in a conventional environment, with and without dietary supplements of penicillin

Abstract

It is now generally accepted that the increased rate of weight gain in chicks receiving dietary antibiotics depends largely, if not entirely, on consequent modification of the microbial population of the chick's alimentary tract. Fundamental investigation of the phenomenon, therefore, calls for the maintenance of chicks free from indigenous organisms so that a defined flora can be introduced as desired. We deal here with experiments on the rearing of chicks in the Gustafsson (1948, 1959) germ-free apparatus and the effects of dietary penicillin on chick growth in germ-free or conventional environments. E X P E R I M E N T A LChicks. The chicks were produced on our own premises from Light Sussex hens crossed with Rhode Island Red cocks, so that the sexes were distinguishable at hatching by down colour. For much of this work the hens were housed in batteries and artificially inseminated twice weekly, fouling of the egg-shells being thus avoided as far as possible. On some occasions the hens were flock-mated in fold units on grass; some of the eggs from these birds were soiled, and only the cleanest were selected for the production of germ-free chicks.Gerrn-free apparatus. Three of the small light-weight tanks (see P1. I ) designed by Gustafsson (1959) and supplied by Wojidkow and Co. A. B., Malmo, Sweden, were used. The tank consists essentially of a stainless steel box, 34 in. long, 18 in. wide and 20 in. deep, covered by a plate-glass window. Into one of the sides a pair of heavy rubber sleeves is sealed, to which can be fitted rubber gloves of any suitable pattern. A third sleeve is provided on the opposite side. At one comer of the tank is a stainlesssteel U-trap to be filled with germicide, through which objects can be passed into or out of the tank. The air supply is sterilized by passing it through a steel cylinder containing granulated carborundum heated electrically to 3 50"; it is cooled by passing through a tube along the side of the tank. The exhaust air is similarly treated in order to destroy any organisms that may, deliberately or accidentally, have been introduced into the apparatus. In the experiments described here air was passed into the tanks at the rate of 7l./min during the hatching period, and subsequently the flow was increased to 10 l./min. Positive pressure was always maintained in the tanks. M. E. COATES AND OTHERS I963The apparatus was originally designed for rats; small modifications had to be made to meet the more exacting environmental requirements of young chicks. During the hatching period a relative humidity of about 65 % is optimal and was achieved by dripping water slowly into the air-intake tube as it entered the air sterilizer. After hatching, ordinary atmospheric air was supplied through the sterilizer until the birds were 2-3 weeks old, by which time humidity in the tanks began to rise because of the chicks' respiration and of evaporation from droppings and water troughs. At this timethe air entering the tanks was dehumidified bypassing it over a freezing coil at -j' bef...

Microbial shifts in the swine distal gut in response to the treatment with antimicrobial growth promoter, tylosin

“…This hypothesis is partly based on the understanding that AGPs lack growth promoting effects in germ-free animals (8,19) and because many antimicrobials with different modes of action promote animal growth. The work presented here was designed to better understand the effects that a single AGP, tylosin, has on the fecal microbiome of the pig.…”

“…Early studies demonstrated that oral antimicrobials did not have growth-promoting effects when given to germ-free animals (8). Therefore, it is likely that growth promotion is based on changes to the gut microbiota.…”

Physiological responses of growing pigs to high ambient temperature and/or inflammatory challenges

“…Those studies include the experiment of Coates et al (1963) with chickens housed in a germ-free environment and more recent studies comparing pigs reared in good or poor sanitary conditions (Le Floc'h et al, 2009;Le Floc'h et al, 2010). Such changes result essentially from the reduction in feed intake, the redistribution of nutrients from growth towards the immune system response (Johnson, 1997;Spurlock, 1997;Le Floc'h et al, 2004), and the decrease in nutrient digestibility (Le Floc'h et al, 2014).…”

Influence of environmental stress on immunity of swine

“…(9) oraz Coatesa i wsp. (2). Wykazano w nich, że kurczęta trzymane w regularnie dezynfekowanych klatkach lub w środowisku wolnym od drobnoustrojów rosły szybciej niż te, które trzymano w warunkach o niskim stopniu higieny.…”

“…U zwierząt przebywających w czasie chowu w śro-dowisku o niskim stopniu zanieczyszczenia mikrobiologicznego profilaktyczne podawanie antybiotyków ma z reguły znacznie mniejszy pozytywny efekt produkcyjny (2,9,17). Antybiotyki uważane są zatem za promotory wzrostu między innymi dzięki ograniczaniu patogennego działania drobnoustrojów, z którymi, jeżeli się ich nie stosuje, zwierzę musi uporać się samo, kosztem mniejszych przyrostów m.c.…”