Comparative analyses of layer males, dual purpose males and mixed sex broilers kept for fattening purposes regarding their floor space covering, weight-gain and several animal health traits

Abstract

As a major part of world poultry production is specialised in meat or egg production, millions of day-old male layer chicks are culled in Europe each year. Within the present study, about 500 birds each of three genetic lines, Lohmann Brown (LB), Lohmann Dual (LD) and Ross 308 were fattened separately in a poultry floor management system over an eleven-week period. At regular intervals 55 birds per line were weighed and the floor space covered by their bodies was calculated using planimetric measurements. Furthermore, several animal health traits were assessed within the final two weeks of fattening. The mean floor area occupied by one-week old Ross 308 broilers was approximately 1.5‑fold higher compared to those of LB and LD at the same age and extended up to more than twice the space with increasing age. The highest mean body weight was measured for Ross 308, followed by LD and LB. While uniformity of the LB flock was high at any time body weights of LD and Ross 308 encompassed a wide range, resulting in a low uniformity within these groups. None of the examined LB and LD chickens showed keel bone deformities, breast plumage pollution or foot pad dermatitis. In contrast, all of the Ross 308 broilers had moderate to severe pollution of breast plumage and up to 27% showed lesions on at least one foot pad at the end of the fattening period. About 91% of the LD and 56% of the LB chickens showed lesions at the comb and/or wattle at the end of the fattening period, indicating aggressive male-male interactions within these groups. The mean eviscerated carcass weight was almost four times higher for Ross 308 (4.11 kg) than for LB (1.05 kg) and LD (1.03 kg).