Department of Animal and Poultry Health and Nutrition, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
In a 2 3 2 factorial arrangement, 144, fifty–four-week-old laying hens, in 12 treatments with 12 replicates for each treatment, received one of 12 diets based on maize or wheat containing three levels of dried tomato pomace (DTP: 0, 50 and 100 g/kg) as a substitute for wheat bran, and two levels of pigment (0 and 900 mg/kg), for 9 weeks. Weight gain (WG), egg production (EP), egg weight (EW), egg mass output (EM) and feed intake (FI) were determined. Shell weight (ShW), shell thickness (ShT), Haugh unit (HU) and yolk colour score (YCS) were also measured. Maize decreased body weight of the birds and increased HU, ShW/EW ratio, ShT, and YCS of the eggs when compared with wheat diets. DTP had no effect on these parameters, but increased YCS. Pigment reduced ShW/EW ratio and ShT, but increased YCS of the eggs. There were significant interactions between the source of energy (ES) and DTP on ShT and YCS of the eggs. There were also interactions significant between ES and pigment on ShT and YCS. As an alternative for wheat bran, 100 g/kg of DTP produced comparable egg quality and laying performance, and it contributed to a deeper yolk colour.