Analysis of laying traits in first cycle geese in two production systems

The phenotypic relationships between the components of the number of eggs per goose in the first laying cycle were estimated in two systems: S1 consisted of geese used for fatty liver pro- duction (Grey Landes) and reared in mating pens with natural lighting; S2 consisted of meat produc- tion geese, reared in individual cages under controlled lighting conditions. Criteria of the laying rhythm were defined and estimated, according to the phenomenon of laying clutches. A clutch was defined as the number of eggs separated by an interval of 48 h at most. Intervals greater than 48 h were defined as pauses. Differences between the two systems (S1 vs. S2) were obvious for all traits investi- gated, with dramatic effects on the total number of eggs (37.8 vs. 72.0), the laying duration (92.3 vs. 156.2 d), the average clutch length (4.4 vs. 7.7 eggs), the average pause duration, the percent of pro- ductive time and the within clutch interval between consecutive eggs (41 vs. 43 h). The difference in total egg number between S1 and S2 production systems appeared to be due to a difference in clutch length rather than to a difference in the number of clutches. Except for the correlations involving the number of clutches and other components of egg production (number of eggs, laying intensity or pause duration), the two systems showed a great similarity in the pattern of phenotypic correlations between component traits of total egg production. High positive correlations were found between to- tal egg number and its components, laying duration and laying rate. Correlations between egg number and characteristics of clutches were also similar across systems, except for the number of clutches: egg number was positively correlated with clutch length and negatively with pause duration.