The effect of low-density diets on broiler breeder development and nutrient digestibility during the rearing period

Low-density diets might help to reduce hunger feeling in restricted-fed broiler breeders. Effects of low-density diets on nutrient digestibility and bird development were studied in Cobb 500 broiler breeder hens from 4 wk of age until the onset of the lay (wk 26). The experiment included 4 treatments. The control treatment was a normal density diet (ND; 2,600 kcal/kg). Treatments 2 and 3 had a 12 and 23% lower nutrient density than ND (LD12 and LD23, respectively) through inclusion of palm kernel meal, wheat bran, wheat gluten feed, and sunflower seed meal. Treatment 4 also had a 12% lower nutrient density than ND but included oats and sugar beet pulp (LD12(OP)). Total daily intake of energy, digestible lysine, calcium, retainable phosphorus, sodium, and linoleic acid was kept constant in the low-density dietary treatments. Animal performance and development of the intestinal tract and reproductive tract were determined in addition to digestibility and feed passage rate. The LD12(OP) provided a lower AME and nutrient digestibility than calculated and was related to lower live weights. Birds given LD23 and LD12(OP) showed a faster ovarian and oviduct development between wk 24 and 26 compared with ND. At 22 wk of age, LD23 and LD12(OP) diets resulted in higher empty jejunum and ileum weights. Low-density diets did not affect intestinal tract contents and decreased mean retention time of the contents. It was concluded that low-density diets can affect live weight and development of digestive and reproductive tracts.