Comparative mortality and predation in relation to egg production traits of Rhode Island Red, Black Australorp and Hyblack laying hens in scavenging production systems of rural Malawi.

1. Black Australorp (BA), Rhode Island Red (RIR), and Hyblack (HB) birds were used in farm and field scavenging systems in Malawi, to study mortality through disease and predation in relation to laying performance. 2. Predation was higher in BA than HB. 3. Mortality through disease was higher in RIR than BA and HB. 4. Crossbred HB birds show the lowest combination of mortality and predation, suggesting a heterosis effect. 5. Mortality did not differ on farms and in field environments, suggesting an inability to improve biosecurity in farm conditions. 6. There was a positive relationship between eggshell strength and mortality. Calcium depletion from the birds' bones, limiting foraging and escaping ability may be the explanation, which ultimately increases susceptibility to disease and predation.