DOI: https://doi.org/10.21203/rs.3.rs-1478894/v1
Synthetic lines have been developed in hot climate countries over the last few decades through selection for specific goals such as APRI rabbits, and depending on their specialisation, these lines perform better than the standard of the original breeds, and contemporary production tends to rely on them. The aim of the study was to identify and explain genetic parameters in synthetic maternal line (APRI rabbits) under Egyptian conditions. (DFREML) was used to assess data on body weights (BW) at 4, 8, and 12 weeks, also daily gains (DG) at 4-8, 8-12 and 4-12 weeks. Highest heritability (h2) estimate for BW was at 4 weeks (0.10), while the lowest estimate was at 12 weeks (0.03). The highest estimate (0.08) was for h2 of DG at 4-8 weeks, while the lowest estimate was for DG at 8-12 weeks (0.02). All genetic correlations (rg) between BW at different ages were moderate to high and positive; estimates of rg for DG ranged from low to high and were positive, with the exception of -0.84 between 4-8 and 8-12 weeks. BW and DG at different intervals had significance and the highest value in the first parity. BW and DG were significantly different in different seasons (P <0.05), with the highest value in the autumn. Significant differences in BW owing to litter size at birth (LSB) (P<0.05). Moreover, LSB had a significant impact on DG at 8-12 and 4-12 weeks, but not at 4-8 weeks.