Influence of Vitamin B12 and Cobalt on laying performance of hens
The effects of dietary vitamin B12 and cobalt (Co) supplementation on laying performance were investigated in laying hens (Lohmann Brown). A total of 208 laying hens were allocated to 8 groups with 26 hens per group. Hens were kept individually in a cage battery. The trial commenced when the hens were 22 weeks old and lasted for 13 laying months. Feed and water were provided ad libitum. Eggs laid were recorded daily and feed consumption monthly. Eggs were weighed four times in two weeks each month. In the 2nd, 6th and 10th laying months the egg composition was examined. The basal diets (0 g B12; 0.03 mg Co/kg) were formulated to supplement per kg with 0/5/10/20 g B12 and 0.6 mg Co/0.6 mg Co+5 g B12/0.6+10/0.6+20, respectively. The supplementation of 0.6 mg Co per kg feed reduced the daily feed intake (108 g) of hens and this led to reduced laying intensity (90.5 %) compare to other groups. The control and the 0.6 mg Co group laid the lightest (p<0.05) eggs (62.0/61.9 g, respectively) over the 13 month of the trial. The daily egg mass production was also significantly (p<0.05) reduced in the 0.6 mg Co group. Feed conversion (1.87 kg/kg) was particular improved in the 20 g B12+0.6 mg Co group. The treatments had no significant effects on egg composition.