Influence of Vitamin B12 and Cobalt on performance of laying hens
The effect of Vitamin B12 and Cobalt (Co) on laying performance, egg composition, and organ mass and haematocrit was studied in laying hens. A total of 216 laying hens were allocated to 8 dietary treatment groups (0/5/10/20 µg vitamin B12 per kg, 0.6 mg Co, 0.6 mg Co + 5 µg B12, 0.6 mg Co + 10 µg B12, 0.6 mg Co + 20 µg B12) and fed for 13 laying months (364 days). The daily feed intake per hen was significantly increased in the mean value of the total laying period of the 5 µg B12-Group compared to the other B12-Groups and the Control. The laying intensity was ranged between 90 to 93 % and was not different between groups. The egg weight and the daily egg mass production were significantly increased with supplementation of vitamin B12 (all groups) and B12 x Co. Feed conversion was significantly improved in the group with 5 µg B12 per kg feed and also the combination B12 x Co. The supplementation of 5 to 20 µg B12 to the diet significantly increased the final hen body weight. Co alone without B12 in the diet significantly increased the mass of the eggs and did not change the other laying parameters. Supplementation of diets with vitamin B12 or Co or both additives didn't directly improve the egg composition and the yolk colour. The results of slaughtering showed that supplementation of 20 µg B12 the liver mass decreased significantly and the heamatocrit content increased significantly compared to the Control and the 0.6 mg Co-Group. The supplementation of 0.6 mg Co significantly increased the spleen mass. The results allow the conclusion that a supplementation of 5 µg vitamin B12 per kg laying hen feed was sufficient to compensate the deficiencies on feed intake and laying performance. An additional supplementation of Co to feed does not have additional advantages for the birds.