Reliability of Well-being Indicators in Broilers ISSA

1 Research Institute of Animal Science, BG-2232 Kostinbrod, Bulgaria
2 Trakia University, Medical Faculty. BG-6000 Stara Zagora, Bulgaria


POPOVA-RALCHEVA, S., V. HADJIILIEV, D. GUDEV, A. ALEXANDROV and V. SREDKOVA, 2002. Reliability of well-being indicators in broilers ISSA. Bulg. J. Agric. Sci., 8: 233–238

Broilers (n = 3200) were allocated into 8 pens with males (I group), 8 pens with females (II group) and 8 pens with males + females (III group). Population density was 32 and 16 birds per m2 for broilers up to 3 weeks of age and over that age, respectively.
Aggressive acts were registered by 15 min each hour (900 h – 1200 h) from day for three consecutive days. Plasma corticostrone, glucose and cholesterol levels were measured at 4 and 6 weeks of age immediately after the termination of the ethological observation. Adrenal and bursal weights were measured at 6 weeks of age, immediately after the decapitation of the birds.
At 4 weeks of age plasma corticostrone levels were significantly higher in III group of broilers in comparison with those of I group (P < 0.001) and II (P < 0.01) group. At 6 weeks of age plasma corticostrone levels in all groups were lower relative to those at 4 weeks of age, but significantly higher in III group of broilers in comparison with those of I group (P < 0.001) and II group (P > 0.05). These changes corresponded to the levels of cholesterol and the dynamics of the manifested aggressive acts. Plasma glucose levels did not correspond to corticosterone levels in the respective groups. There were not significant differences in adrenal and bursal weights between the groups.
These results show that the ethological parameter “aggressiveness”, plasma corticosterone and cholesterol level can be used as reliable indices for the extent of the social stress endured by birds. Adrenal and bursa weights turned out to be inappropriate indicators for broiler well-being in the conditions of our experiment.

Key words: well-being, aggressiveness, corticostrone, cholesterol
Abbreviations: HPA– hypothalamic-pituitary-adrenal, ACTH-adrenocorticotropin