The European Union's poultry industry needs to improve the production system of broiler breeder hens and the quality of the resulting products if it is to compete more effectively. Breeder hens overeat, become fat, suffer various pathologies and have poor reproductive ability. Severe rationing improves their health and reproduction, but current rationing regimens cause undue hunger. Product quality and the hen's welfare needs may be adversely affected by rationing.
This project aims to improve production and reproduction in an existing conventional farming system - the production of day-old chicks from breeding stock for fattening as table poultry. This project will determine whether the unlimited growth requirement of broiler breeder hens can be allied with good product quality, good reproductive performance, good health and welfare either by a feed restriction protocol that does not cause undue hunger, or by innovative genetic selection. The two main objectives are:
1) to define, understand and improve the relationship between the product quality and the genetics and nutrition of breeders
2) to find genetic potential for improving egg production and welfare without deteriorating the quality of chick production through an understanding of the interaction between reproduction, feed restriction and different genotypes of
3) to adapt feeding regimens more closely to the animals' needs, thus improving the welfare.
Progress to Date
The work achieved in the first year of this project has attained the first milestone - defining common methodology. The most important feature of this milestone is the definition of the strains of bird to be used in the vast majority of the experiments performed in the framework of this project (with the exception of some work on genetics to be performed at Roslin). These strains will be referred to in the results as:
L íV - a 'Label' strain. Slow growing strain used for the quality market. This serves as a control strain.
E íV - an experimental broiler breeder strain bearing the 'dw' dwarf gene. This strain has a decreased need for rationing.
SR íV - a standard broiler breeder raised on restricted feeding according to the breeder's technical guide.
SA íV - the same broiler breeder strain raised on ad libitum feeding.
1) Preliminary work for defining chick quality, on an a priori basis, has been completed on a commercial broiler strain. A scoring method was tested on a series of chicks hatched from fresh and stored eggs from breeders of different ages. Results using this scoring system show that fresh eggs produced greater number of high quality chicks compared with stored eggs and that the number of low quality chicks increases the longer eggs are stored. Older breeders produced lower quality and more heterogenous chicks than younger breeders did, especially when eggs were stored.
2) Advances were made in understanding the links between feeding, growth and reproduction. These were focused on:
a) the metabolism of the growing broiler breed
b) the reproductive physiology of the growing and the adult broiler breeder.
Investigations were performed into the effects of restricted feeding on blood glucose, insulin and leptin concentrations. Feed-restricted animals showed higher blood insulin and glucose when fasted compared to the non-restricted group indicating that, at this point in the project, it is not possible to attribute an insulin resistance state to ad-libitum-fed broiler breeder chickens. Endocrine measurements indicate that food-restriction most likely induces a higher sensitivity to energy intake. It was also shown that, despite the reduced fat pad size in feed-restricted chickens, their blood leptin concentrations were similar to that of ad-libitum-fed breeder chickens, at least in when fasted.
To study the ontogeny of the IGF system in the avian ovary, six hens per treatment (L, E, SA and SR) were slaughtered at four-week intervals following hatch up to sexual maturity. No significant differences were observed between SA and SR.
To compare the effect of feed intake on the follicular hierarchy, the yellow follicles were first counted, measured and weighed. The size and weight of the first follicle was not statistically different between the four treatments but the number of yellow follicles was lower in the L strain.
3) The three genotypes (S, E & L) were tested-fed ad libitum or feed-restricted (for S) according to normal commercial guidelines. Individual behavioural time budgets were collected from day-old until 36 weeks of age. Individual time budgets of individual breeder hens were not predictable from one age to another by the scan sampling procedure used in the present experiment.
The experimental dwarf genotype E tested with a diluted diet was much more resistant and performed better under the unrestricted feeding programme than the standard broiler breeders. E birds also consistently spent more time resting than the other strains.
The state of the ovarian follicular hierarchies suggested a slower growth rate of the yellow follicles in the ad-libitum-fed breeders, and this requires further research.
Scientist responsible for the project
Dr MICHEL PICARD
CENTRE DE RECHERCHES DE TOURS
France - FR
Phone: +33 2 47 42 78 40
Fax: +33 2 47 42 77 78
||Institut National de la Recherche Agronomique
||01 September 2001
||2 637 146 €
|Total EC contribution
||1 510 921 €