Institute for Animal Science and Technology, Universitat Politècnica de València, Valencia, Spain.
Department of Animal Production, Faculty of Agriculture at Moshtohor, Benha University, Tukh, Egypt.
J Anim Breed Genet. 2021 Jul;138(4):508-517. doi: 10.1111/jbg.12543. Epub 2021 Mar 8.
The enhancement of rabbit female functional longevity, that is the ability to avoid voluntary culling, is a paramount aspect for the sustainability of meat rabbit production; this trait represents a direct indicator of female robustness. The objective of our study was to compare the functional longevity of five rabbit lines at their foundation and at fixed times during their selection processes. Four of them are maternal lines (A, V, H and LP) selected for litter size at weaning. The fifth line is the paternal line R, founded and selected for post-weaning daily gain from 28 to 63 days. The comparison at foundation involved the complete data set (from March 1980 to March 2013; records of 15,670 does) and pedigree (19,405 animals). Latter comparisons were made when all lines shared the same environmental and management conditions, from March 1997 to September 1998 and from March 2011 to September 2012. In these second comparisons, the same model as that used in the comparison at foundation was used, but now the additive effect was excluded, only data from the corresponding periods were considered. At their foundation, lines V, H and LP showed larger functional longevity than lines A and R, being LP line that with the longest productive life. In the latter comparisons, lines A and R still showing the lowest functional longevities. However, as the selection process evolves, the differences between these two lines and the others were reduced. It could be concluded that the average longevity of a population greatly depends on the criteria followed for its foundation. In addition, along the selection for litter size, the differences of longevity between lines tend to decrease, this is due to an unintended selection for functional longevity, since only offspring from females reaching three parturitions are selected as breeding animals for the next generation.
提高兔群雌性的功能寿命，即避免自愿淘汰的能力，是肉兔生产可持续性的一个至关重要的方面；这一特性是雌性健壮程度的直接指标。我们的研究目的是比较五个兔群在基础群和选择过程中固定时间的功能寿命。其中四个是母系（A、V、H 和 LP），选择断奶窝仔数。第五个系是父系 R，成立并选择从 28 日龄到 63 日龄的断奶后日增重。在基础群的比较中，使用了完整数据集（1980 年 3 月至 2013 年 3 月；15670 只母兔记录）和系谱（19405 只动物）。后来的比较是在所有系都共享相同的环境和管理条件下进行的，时间是 1997 年 3 月至 1998 年 9 月和 2011 年 3 月至 2012 年 9 月。在这两次比较中，使用了与基础群比较中相同的模型，但现在排除了加性效应，只考虑了相应时期的数据。在基础群中，V、H 和 LP 系的功能寿命比 A 和 R 系大，其中 LP 系的生产寿命最长。在后一次比较中，A 和 R 系仍然显示出最低的功能寿命。然而，随着选择过程的发展，这两条线与其他线之间的差异减少了。可以得出结论，一个种群的平均寿命在很大程度上取决于其基础的标准。此外，随着对窝仔数的选择，系间的寿命差异趋于减小，这是由于对功能寿命的无意选择，因为只有达到三胎的母兔的后代才能被选为下一代的繁殖动物。
