Short- and long-term effects of weaning on adrenocortical and functional response of lambs
Fazio, EsterinaMedica, PietroCravana, CristinaFerlazzo, Adriana
Background: Weaning period is considered a crucial event in the management of ewes and lambs, resulting in a number ofsignifi cant challenges. Although multiple stresses signifi cantly affected adaptative capability of ewes in terms of changes inphysiological mechanisms insuffi cient knowledges are available to understand the adrenocortical and functional responsesof lambs to adapt to weaning stress. The main objective of the present study was to evaluate the effect of weaning associated with maternal separation on circulating cortisol concentrations, respiratory rate and rectal temperature changes afterthe fi rst 24 h weaning period and 2 weeks later in cross-bred lambs.Materials, Methods & Results: Thirty-four cross-bred lambs were assigned randomly to two treatments: 17 (unstressedcontrol group) were housed in standard farming conditions with their mothers and 17 lambs (treated group) were submitted to weaning and separation from maternal care. Both groups were studied and sampled 2 weeks before (weaning) inbaseline conditions (T0), 24 h (T1) and 2 weeks (T2) after (weaning). In treated group lambs showed decreases of cortisolconcentrations 24 h after (P < 0.001) and 2 weeks after (P < 0.05) weaning, compared to baseline values. Weaning effectswere shown for cortisol changes (P < 0.0001) in treated lambs. The comparison between control and treated lambs showedlower cortisol concentration both 24 h after weaning (P < 0.001) and 2 weeks later (P < 0.05) in treated than control subjects. Treated lambs showed decreases of respiratory rate 24 h after (P < 0.01) and 2 weeks after (P < 0.05), compared tobaseline values, with a signifi cant weaning effects for RR changes (P < 0.001). No signifi cant changes were observed forRT at different times in treated lambs. Negative and signifi cant correlations were observed between RR and RT (r= -0.674;P < 0.05) for all measurement periods in control group...(AU)
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