Use of lipopolysaccharide (E. coli) as stress inducing in sheep in intermediate stage of pregnancy / Uso de lipolissacarídeo (E. coli) como indutor de estresse em ovinos na fase intermedíaria da gestação

ABSTRACT

To analyze stress during the intermediate stage of gestation, 43 multiparous, crossbred Santa Inês, pregnant ewes, with a average age of 5 and average body weight (BW) of 60kg, were challenged with a intravenous administration of 0.8µg.kg-1 of LPS (lipopolysaccharide E. coli - outer membrane cell of gram-negative bacteria), diluted in physiological saline solution - simulating an immune stressor. The females were placed in individual cages at feedlot, with adaptation period of 5 days before the begin of sampling, with free access to good water quality, shade and food in the trough (corn silage and mineral supplementation). The ewes were divided into three groups, with a completely randomized design (CRD) CG - control group, with 15 animals that were not subjected to stress; IG - intermediate group stage, with 14 animals undergoing stress at 70 days of gestation; FG final group, made up of 14 animals undergoing stress at 120 days of gestation. The variables used to investigate stress were measured during the intermediate stages of pregnancy in a 24 hour sampling, with this was possible to observe the change in rectal temperature (RT) and blood levels of cortisol by its circadian rhythm. Shortly after the baseline sampling, the treatment corresponding to the intermediate stage of gestation was submitted to stress, with the sampling interval of one hour each, from the first to

RESUMO

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