Tick infestation and associated diseases (i.e., babesiosis) constitute major drawbacks for improvement of beef cattle productivity in the tropics, mainly when purebred and crossbred taurine animals are used. Host-parasite-pathogen interactions form complex biological systems that are poorly understood and which significantly affect production and quality traits in ways yet to be dissected and described. This research was carried out to investigate potential causal relationships, through the use of structural equation modeling (SEM), among tick counts (TC), Babesia bovis infection level (IB) and the gains in weight: from birth to adjusted weaning age (WG), and from weaning to yearling (YG). Statistical analyses were conducted in three steps: 1) Partition of (co)variances into genetic and residual components using Bayesian multiple-trait modeling (MTM); of 2) Search for plausible causal structures by applying the inductive causation (IC) algorithm to the residual (co)variances obtained in the first step; and 3) Final analysis using SEM, which was based on the causal network learned from the IC algorithm. The most plausible results comprised three direct links between traits: WG→YG, TC→WG, and WG→IB with structural coefficients posterior means equal to -0.3026, 6.3620, and 0.0004, respectively. The final inferred directed acyclic graph (DAG) suggests that interventions on TC would directly affect WG, which would then affected YG; moreover, WG could also present a small positive effect on IB.

ick虫感染和相关疾病（即杆状虫病）构成了热带地区提高肉牛生产率的主要弊端，主要是在使用纯种和杂交牛磺酸动物的情况下。宿主-寄生虫-病原体的相互作用形成了复杂的生物系统，人们对其了解甚少，并且以尚未剖析和描述的方式极大地影响了生产和品质特性。这项研究是通过使用结构方程模型（SEM）在壁虱计数（TC），牛肝菌（Babesia bovis）中调查潜在的因果关系而进行的感染水平（IB）和体重增加：从出生到调整的断奶年龄（WG），从断奶到一岁（YG）。统计分析分三个步骤进行：1）使用贝叶斯多特征模型（MTM）将（协）方差分为遗传和残留成分；of 2）通过对第一步中获得的残差（协方差）应用归因因果（IC）算法来寻找合理的因果结构；3）使用SEM进行最终分析，该分析基于从IC算法中获知的因果网络。最合理的结果包括性状之间的三个直接联系：WG→YG，TC→WG和WG→IB，其结构系数在后均值分别等于-0.3026、6.3620和0.0004。最终推断的有向无环图（DAG）表明，对TC的干预将直接影响WG，然后会影响YG；此外，工作组还可能对IB产生较小的积极影响。