On the basis of a pilot study by Smulders and Enting (unpublished) and a study by Zuidhof et al. (1995), it was questioned whether low-density diets could improve broiler breeder welfare and how observed effects of low-density diets on initial offspring growth and offspring mortality could be explained. Therefore, a second study with low-density broiler breeder diets was performed. The objectives of the study were:
- To investigate the effect of low-density diets on broiler breeder development, bird behaviour, stres physiology and feed intake motivation.
- To relate changes in egg weight, egg composition and embryonic development to changes in offspring performance and mortality
[Results]:
Low-density broiler breeder diets:
1). give indications for an improved bird welfare.
2). delay ovary and oviduct development and, as a consequence, increased subsequent egg weights,
3). improve the early development of the area vitellina externa and increase embryo weight. This is related to the increase in egg and egg white weight,
4). can increase growth rate offspring due to a higher intake of digestible nutrients,
5). can reduce mortality rate offspring. This is related to increased egg and egg white weights.
6). decreased IgM and IgG titres in offspring from 29 week-old broiler breeders and increased these titres in offspring from 60 week-old broiler breeders. |
