Effects of slaughter age and cage type on carcass and meat characteristics of laying hens

Laying hens are reared especially for egg production. However, at the end of their production period, they are slaughtered, and carcasses are consumed as meat or meat products. Thus, the quality of such meat is an important attribute for both consumers and manufacturers. Therefore, the present study was designed to examine the effects of slaughter age and cage type on some carcass and meat characteristics of laying hens. For this purpose, a total of 840 ISA-Brown laying hens from 16 weeks of age to the end of the experiment at 75 or 108 weeks were reared in unenriched or enriched cages with 21 cages/type and 20 laying hens per cage. The production period was extended to 108 weeks of age via induced molting using whole barley diet. At the onset of 75 and 108 weeks of age 18 birds from each cage type were slaughtered. Advancement in the slaughter age contributed to heavier hot carcass and liver weights whilst a decrease in thigh and gizzard percentages were recorded. Increased slaughter age was also characterised by a change in the colour attributes of meat being darker/redder/yellower when compared to the younger hens. Meat characteristics as dry matter, crude protein, fat, total ash, and collagen content were also increased with slaughter age. Housing differences in terms of cage system had a limited effect on carcass and meat characteristics, but it was noted that hens reared in enriched cages had higher thigh and gizzard percentages with increased collagen content in their meat. Some interactions were also noted between slaughter age and cage type. In conclusion, the results suggested that advancement in slaughter age of laying hens is accompanied by changes in carcass and meat characteristics of laying hens whilst role of cage type in determining these changes is minimal; however, further research is needed with additional sensory evaluation of meat.