Influence of Dietary Zinc Supplementation on Turkey Welfare During the Hot Summer Period. II. Hormonal and Biochemical Aspects
2010
Bozakova, N., Thracian University, Stara Zagora (Bulgaria)
In hot environment conditions, the utilization of different feed supplements for improving poultry welfare depending on the specific production systems is especially relevant. Reliable indicators of poultry welfare, together with the behaviour, are the changes in plasma corticosterone levels and the related alterations in some blood biochemical indices. The aim of the present study was to follow the changes in plasma corticosterone levels and some blood biochemical indices in female turkey breeders during the thermoneutral and hot summer period, as well as the possibility for their welfare improvement by supplementation of feed with 35 mg/kg Zn - Zinteral 35, containing 35% Zn. The high ambient temperatures and low air humidity during hot summer days were a considerable stress factor for turkeys and they provoked significantly higher blood corticosterone, cholesterol, glucose and urea, compared to the thermoneutral period - P0.01. The Zn supplementation at 35 mg/kg significantly reduced blood corticosterone - P0.01, cholesterol - P0.05, glucose - P0.05, urea - P0.01 levels and increased total protein - P0.05 in female turkey breeders during the hot summer days, thus evidencing heat stress alleviation and improvement of their welfare.
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