The effect of body weight prior to molting in brown laying hens on egg yield and quality during second production cycle

Abstract

This study focused on the effect of different BW in moulted brown laying hens (Isa-brown) on egg yield and quality during second production cycle. A total of 240 hens after the completion of first production cycle were classified into 4 BW groups; Light (L; 1529-1823 g), Mid-light (ML; 1824-1977 g), Mid-heavy (MH; 1990-2120 g) and Heavy (H; 2124-2797). Groups were consisted of 6 replications and in each replication there were 10 hens reared in individual cages. Moult was induced by feeding hens a commercial compound feed containing high levels of added Zn (15,000 ppm) as Zn oxide during the first 10 days, and following 40 days they were fed laying diet (17% crude protein and 2700 kcal ME/kg; 75 g/day). At the end of moulting period, BW loss was higher (P<0.01) in hens in MH (%17.30) and H (18.42%) groups compared to those in L (11.41%) and ML (11.42%) groups. In second production cycle (147 days), no differences were found among groups in terms of egg yields, but the peak yield of the H hens did not reach those of other groups (P< 0.05). Egg weight of L hens (69.5 g) was lower (P<0.05) than that of ML (70.8 g), MH (71.9 g) and H (71.9 g) hens. Heavy groups had higher feed consumption (P<0.01) and feed conversion ratio (P<0.05) compared to light groups. These results show that mid-light BW of flock prior to molting result in better egg weight, feed consumption and feed conversion ratio in the second production cycle. © Asian Network for Scientific Information, 2004.