Goats, even though adapted to tropical environments, are exposed to infection by endoparasites during grazing, which can negatively affect the time a female stays in the herd, compromising the breeding efficiency. In this context, the objective of this study was to evaluate a gamma-Gompertz shared frailty model for correction of unobserved heterogeneity attributed to the effects of unmeasured factors in analyzing the time of stay in a herd of Anglo-Nubian goats, using the survival analysis technique. The method was applied using data from records of 101 does born in the period 2009–2013 in an experimental herd located in the municipality of Teresina, Piauí, Brazil, where the replacement was carried out over four generations, with bulls from other herds and females incorporated regardless of the value of their EPG exam, to increase the variation of sensitivity to worms in the herd. The removal of a doe due to death caused by worm infection was considered the event of interest (failure) and losses due to other causes were considered censored events. According to the model selection criteria (AIC and BIC), the shared gamma-Gompertz frailty model stood out from the gamma shared frailty models with risk functions based on the Weibull and log-logistic distributions for the proposal studied. The gamma-Gompertz shared frailty model (with and without effect of observed factors) allowed observing a significant influence of the of year-season effect, indicating as frailty effects the differentiated death tendency between years (does born in 2011 in the rainy season and 2012 in the more fragile dry season). When associating the random effect to groups formed by goats descended from the same father, a significant association was observed between the times of goats belonging to such groups, with only 2 bulls showing more fragile daughters and consequently less permanence in the herd. The use of frailty models is relevant to meet the objectives of animal husbandry, as a technique to identify frailties due to the effects of factors that are difficult or costly to measure in bulls classified as having high genetic value. The simplicity and presentation of results in the form of graphs that are easy to understand make the method attractive for this type of research.

山羊尽管适应热带环境，但在放牧期间容易受到内寄生虫的感染，这可能会对雌性在畜群中停留的时间产生负面影响，从而损害了繁殖效率。在这种情况下，本研究的目的是评估一个伽玛-戈姆佩茨共享脆弱模型，该模型用于校正生存率分析中不可观测的异质性，该异质性归因于不可测因素在分析盎格鲁-努比亚山羊群的停留时间方面的影响。技术。该方法是使用来自2009年至2013年期间101头母猪的记录的数据来应用的，该母猪位于巴西皮奥伊州特雷西纳市的一个实验牛群中，在那里进行了4代的代换，其他公牛和雌性中的公牛不论其EPG考试的价值如何，增加对蠕虫的敏感性变化。由于蠕虫感染而导致死亡而去除母鹿被认为是关注事件（失败），而由于其他原因而造成的损失也被视为审查事件。根据模型选择标准（AIC和BIC），共享的gamma-Gompertz脆弱模型在具有Weibull和对数逻辑分布的风险函数的gamma共享脆弱模型中脱颖而出。伽玛-戈姆珀兹共享的脆弱模型（有或没有观测因素的影响）可以观察到季节效应的显着影响，表明脆弱性影响了不同年份之间的死亡趋势（2011年出生于雨季，2012年出生）在较脆弱的干旱季节）。当将随机效应与同一父亲的山羊组成的群体相关联时，在属于此类群体的山羊的时间之间观察到显着的关联，只有2头公牛表现出更多的脆弱女儿，因此在群体中的持久性较低。脆弱模型的使用对于满足畜牧业的目标具有重要意义，因为该技术可用于识别因遗传价值高的公牛难以或昂贵的因素而造成的脆弱性。结果的简单性和易于理解的图表形式使该方法对此类研究具有吸引力。只有2头公牛表现出更多的脆弱女儿，因此种群中的持久性降低。脆弱模型的使用对于满足畜牧业的目标具有重要意义，因为该技术可用于识别因遗传价值高的公牛难以或昂贵的因素而造成的脆弱性。结果的简单性和易于理解的图表形式使该方法对此类研究具有吸引力。只有2头公牛表现出更多的脆弱女儿，因此种群中的持久性降低。脆弱模型的使用对于满足畜牧业的目标具有重要意义，因为该技术可用于识别因遗传价值高的公牛难以或昂贵的因素而造成的脆弱性。结果的简单性和易于理解的图表形式使该方法对此类研究具有吸引力。