Effect of low-density diets on broiler breeder and offspring performance

Restricted feeding of broiler breeders is required to obtain good reproductive performance. Current practical feed restriction levels can result in hunger feeling and chronic stress, particularly during the rearing period. On the basis of literature data, low-density diets might improve bird welfare. Recent findings also indicate that low-density broiler breeder diets can reduce offspring mortality. In this thesis, effects of low-density breeder diets on bird welfare and breeder and offspring performance were evaluated. Breeder treatments involved: 1) normal density diets (ND), 2) diets with 12 and 11 % reduced nutrient densities during rearing and laying (LD12 and LD11), 3) diets with 23 and 21 % reduced nutrient densities during rearing and laying (LD23 and LD21), 4) as 2), but with oats and sugar beet pulp instead of palm kernel meal, wheat bran, wheat gluten feed and sunflower seed meal in the diets (LD12 ^OP and LD11 ^OP ), and 5) LD11 diets during rearing followed by ND diets during laying.<o:p></o:p></span>Feeding LD23 diets reduced stereotypic pecking behaviour and increased time spent on sitting during the first half of the rearing period. LD23 and LD12 ^OP diets reduced feed intake motivation during rearing. It was concluded that LD23 can improve bird welfare during the first half of the rearing period. However, LD21 impaired bird welfare during laying.<o:p></o:p></span>LD12 ^OP and LD11 ^OP diets gave significantly lower live weights during rearing and laying</span>. Low-density diets delayed reproductive tract development at 24 weeks of age, which was followed by an increased development between week 24 and 26. Changes in bird development were related to changes in nutrient digestibility and utilization of digested nutrients. Egg weights and amount of egg white increased and embryonic development was improved on low-density diets. Laying percentage was significantly higher on LD11 diets. LD11 diets increased live weight of offspring of 29-week-old breeders significantly in comparison with ND diets. Low-density breeder diets resulted in a significant reduction in offspring mortality when breeders were 60 weeks of age. Antibody titres in offspring indicated that nutrients in eggs with a relatively low weight were used for growth rather than for immune system development. It was concluded that low-density broiler breeder diets can improve offspring performance and offspring vitality