Effect of indomethacin on hyperthermia induced by heat stress in broiler chickens.

An investigation was carried out to verify whether the heat stress hyperthermia response of broilers is prostaglandin-dependent. Male broiler chickens of the Hubbard-Petterson strain, aged 35-49 days, were used. Chickens were injected with indomethacin (1 mg/kg intraperitoneally) 15 min before or 2 h after heat exposure (at 35 degrees C for 4 h), and rectal temperature was measured before injection and up to 4 h thereafter. Birds were separated into two groups with and without access to water during heat stress. The increase in rectal temperature was lower (P < 0.05) in birds with access to drinking water during heat exposure. All birds injected with indomethacin exhibited an increase in rectal temperature, irrespective of whether indomethacin was administered before or in the course of the rise in temperature. The results revealed that the increase in rectal temperature during heat exposure is not prostaglandin-dependent, and that the use of cyclooxigenase inhibitors is not recommended to attenuate heat stress hyperthermia in broiler chickens.

Effects of endotoxin, interleukin-1 beta and prostaglandin injections on fever response in broilers.

1. The effect of endotoxin, interleukin-1 beta and prostaglandin on fever response was studied in 80 broilers (Hubbard strain). Endotoxin (E. coli, LPS) was injected i.v. (1.5 micrograms/kg) and icv (1.5 micrograms/bird); interleukin-1 (human recombinant IL-1 beta, 80 pg/bird) and prostaglandin E2 (5 micrograms/bird) were injected icv. Indomethacin (10 mg/kg, i.v.) pretreatment was also used before i.v. endotoxin injection. 2. The results showed that indomethacin was able to block the fever response induced by i.v. endotoxin injection, and IL-1 beta and PGE2 were both effective in producing fever when injected icv. These data suggest a prostaglandin-mediated fever response by broilers, and also a strong evidence of the involvement of endogenous pyrogen (interleukin-1) in fever response in birds.

Effect of age and strain on haematological and gasometric parameters in selected and non-selected broiler chickens

Objetivou-se investigar o efeito de idade e linhagem sobre parâmetros hematológicos e gasométricos de frangos selecionados e näo selecionados. Foram utilizados somente frangos machos, sendo 40 selecionados e 10 näo-selecionados. Amostras de sangue foram colhidas aos 21 e 42 dias de idade e determinados os parâmetros hematológicos (eritrócito, leucócito, hemoglobina, hematócrito, volume globular médio, hemoglobina globular média e concentraçäo de hemoglobina no eritrócito), e os parâmetros gasométricos (pH, pressäo parcial de oxigênio e pressäo parcial de dióxido de carbono). Os resultados mostraram que os parâmetros hematológicos e gasométricos säo afetados pela idade e linhagem do frango. As aves selecionadas apresentaram um número de eritrócito menor e um volume globular médio maior aos 21 dias de idade quando comparados aos animais de 42 dias de idade, e uma relaçäo inversa foi verificada nos frangos näo selecionados. Estes dados sugerem que quando jovens os frangos selecionados podem ser mais sensíveis às alteraçöes nos parâmetros pulmonares e desenvolver a síndrome da Ascite

Influence of age on the febrile response to E. coli and S. typhimurium endotoxins in growing pullets.

1. The effect of bacterial endotoxin injection was studied in growing pullets of different ages. Commercial chicks were divided into 5 groups according to age. Bacterial endotoxins (E. coli and S. typhimurium) were injected intravenously and rectal temperature was measured over a period of 300 min. 2. The results showed no significant effect of age on the febrile response induced by bacterial endotoxins, but a slight tendency towards a reduced fever peak was observed with increasing age. The response latency also increased with age.

Effects of ambient temperature and thyroid hormones on food intake by pigs.

Food intake and plasma thyroid hormone levels (T4 and T3) were higher in pigs acclimated to cold (12 degrees) than hot (32 degrees) environments. The exposure of cold pigs to hot ambient temperature decreased food intake and plasma T4 and T3, whereas for hot acclimated animals the change in ambient temperature (from 32 to 12 degrees) increased food intake and plasma thyroid hormone levels, but the new steady state level of food intake was reached only after 96 hr of temperature transfer despite the rapid change in plasma level of thyroid hormones. Cold-acclimated pigs, when transferred to a hot environment after thyroidectomy, also reduced food intake, but hot pigs shifted to cold ambient temperature after thyroidectomy did not significantly increase food ingestion. The results of this experiment suggest that food intake adjustment depends on the previous living temperature and that thyroid hormones seem to play an important role in increasing the metabolically active mass that probably sustains the new steady state level of food intake, particularly in a cold environment.