Resumen

LEVA, P. E et al. Cortisol en Saliva en Terneros Lechales en la Cuenca Lechera Santafesina. FAVE. Secc. Cienc. agrar. [online]. 2012, vol.11, n.1, pp.7-17. ISSN 1666-7719.

Two calves rearing systems (traditional and modified (SM)) were compared in order to evalúate thermal comfort of suckling Holstein calves during summer and winter. Possibilities to move around and social interaction were improved by SM in both seasons. During winter. animáis were protected with capes, while in summer all animáis had access to shade. Salivary cortisol was measured at four times during the day to detect circadian rhythms. Data were subjected to analysis of variance and to Cosinor analysis. Concentration of cortisol in saliva ranged from 2.06 ± 1.37 to 1.97 ± 1.21 ng/ml in winter and from 0.48 ± 0.23 to 0.38 ± 0.22 ng/ml in summer. Neither management system effects ñor adjustment to circadian rhythms were detected.

Palabras clave : Rhermal comfort; Rearing systems; Suckling calves; Cortisol; Circadian rhythms.

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