The low fertility and offspring survival indicators in alpacas can be partially due to their particularity seasonal reproduction that reduces the opportunities of the females to become pregnant within a season, with the survival of the offspring concerned by the availability of food and exposure to diseases that depends on the calving date. Optimizing the date of delivery and reducing its variability are shown as eligible criteria that could be used as selection criteria within the genetic improvement programmes in alpacas, the calving date being a much more appropriate trait to measure and optimize fertility unlike of age at first calving and the calving interval, this due to the reproductive seasonality in camelids. For this study, 6,533 birth date records were taken between 2001 and 2018 of Peruvian alpacas, to estimate the genetic parameters. Models assuming heterogeneity in the residuals were fitted besides classical homogeneous models to address, not only the possibility of forwarding or delaying the calving date, but also the trend to have parturitions in similar dates. The heritability and repeatability ranged from 0.07 to 0.20 for a homogeneity model and from 0.08 to 0.23 for a heterogeneity model, and suggest the possibility of advancing or delaying the calving date. It should be taken into account that the gestation length of camelids makes it difficult to adapt many reproductive traits, and trying to centre the calving date could delay it. It was concluded the feasibility to genetically select the calving date, also in the production of camels and dromedaries, which have the same reproductive characteristics as alpacas. This selection can be combined with other traits. The heterogeneity model was shown to provide a better fit.

中文翻译：

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产犊日期及其变异性是育种目标中潜在的性状，可解释羊驼的繁殖季节性。

羊驼的低生育力和后代生存指标可能部分是由于它们的特殊性，季节性繁殖会减少雌性在一个季节内怀孕的机会，而后代的生存与食物的可获得性和接触疾病的能力有关。在产犊日期。优化的分娩日期和降低其变异性被视为符合条件的标准，可以作为羊驼遗传改良计划中的选择标准，与第一次分娩和分娩的年龄不同，分娩日期是衡量和优化生育力的更合适的特征。产犊间隔，这是由于骆驼科的繁殖季节。在这项研究中，从2001年到2018年之间，秘鲁羊驼的出生日期记录为6,533，以估计遗传参数。除了经典的均质模型以外，还拟合了假设残差中存在异质性的模型，不仅解决了提前或延迟产犊日期的可能性，而且还提出了在相似日期分娩的趋势。对于同质性模型，遗传力和重复性的范围从0.07到0.20，对于异质性模型，遗传力和重复性的范围从0.08到0.23，这表明提前或延迟产犊日期的可能性。应该考虑到，骆驼科的妊娠期长，很难适应许多生殖性状，而试图确定产犊日期的中心可能会延误它。得出结论，从遗传角度选择产犊日期的可行性，以及在骆驼和单峰骆驼生产中的可行性，这些骆驼和独峰驼具有与羊驼相同的繁殖特性。此选择可以与其他特征结合使用。