High carbon dioxide tension (PCO2) and the incidence of cardiac arrhythmias in rapidly growing broiler chickens

The purpose of this investigation was to determine whether two-week-old rapidly growing broiler chickens with high metabolic activity have an increased risk of the development of heart failure three to five weeks later. The incidence of cardiac arrhythmias was assessed in broiler chickens with either a relatively high carbon dioxide tension (PCO2) or a low PCO2 in their venous blood. Their electrocardiograms (ECGS) were measured when the birds were between five and seven weeks old by means of a biotransplant which allowed them to move freely. Premature ventricular beats were observed in all the birds, but the largest numbers were observed in birds that had had a high PCO2 when they were two weeks old.

Heart rate variability during manual restraint in chicks from high- and low-feather pecking lines of laying hens

The purpose of this investigation was to determine whether there is a difference in coping style in chicks from a high (HFP)- and low-feather pecking (HFP) line of laying hens. Active and passive coping styles can be distinguished by differences in sympathetic and parasympathetic activities on the heart. We studied heart rate during baseline conditions and during manual restraint in HFP and LFP hens. Heart rate and locomotor activity were successfully monitored around the clock with a biotelemetric implant. During the light period, the values for locomotor activity and heart rate were highest, whereas during the dark period they were the lowest. These values did not differ in LFP and HFP hens. However, during manual restraint (restraining the bird on its side by hand for 8 min) HFP birds had somewhat faster heart rate than LFP birds (at 4 min, p = 0.066). Studying heart rate variability during manual restraint showed that LFP chickens had a significant higher parasympathetic activity at 5 min (p = 0.023) and at 6 min (p = 0.002) as compared to HFP hens. The results showed that in terms of coping style, LFP chickens are passive, whereas HFP birds are active.

Plasma catecholamine and corticosterone levels during manual restraint in chicks from a high and low feather pecking line of laying hens

Neurosympathetic and adrenal responsivity to manual restraint was studied in two White Leghorn chicken lines which differ in their tendency to feather peck. Blood samples were taken from freely moving cannulated birds during resting conditions and during manual restraint (placing the bird on its side for 8 min) to determine plasma noradrenaline. adrenaline and corticosterone. Plasma corticosterone levels in low feather peckers (LFP) were significantly higher during resting conditions and restraint as compared to the high feather peckers (HFP). In response to manual restraint the HFP hens showed a significantly larger plasma noradrenaline response than LFP hens. No difference in plasma adrenaline levels was observed under resting conditions or during manual restraint.