Departamento de Anatomía Embriología y Genética Animal, Instituto Agrolimentario de Aragón (IA2), Facultad de Veterinaria, Universidad de Zaragoza, c/ Miguel Servet 177, 50013, Zaragoza, Spain.
Genètica i Millora Animal, Institut de Recerca i Tecnologia Agroalimentàries, 25198, Lleida, Spain.
Sci Rep. 2020 Dec 3;10(1):21190. doi: 10.1038/s41598-020-78346-7.
Perinatal piglet mortality is an important factor in pig production from economic and animal welfare perspectives; however, the statistical analysis of mortality is difficult because of its categorical nature. Recent studies have suggested that a binomial model for the survival of each specific piglet with a logit approach is appropriate and that recursive relationships between traits are useful for taking into account non-genetic relationships with other traits. In this study, the recursive binomial model is expanded in two directions: (1) the recursive phenotypic dependence among traits is allowed to vary among groups of individuals or crosses, and (2) the binomial distribution is replaced by the multiplicative binomial distribution to account for over or underdispersion. In this study, five recursive multiplicative binomial models were used to obtain estimates of the Dickerson crossbreeding parameters in a diallel cross among three varieties of Iberian pigs [Entrepelado (EE), Torbiscal (TT), and Retinto (RR)]. Records (10,255) from 2110 sows were distributed as follows: EE (433 records, 100 sows), ER (2336, 527), ET (942, 177), RE (806, 196), RR (870, 175), RT (2450, 488), TE (193, 36), TR (1993, 359), and TT (232, 68). Average litter size [Total Number Born (TNB)] and number of stillborns (SB) were 8.46 ± 2.27 and 0.25 ± 0.72, respectively. The overdispersion was evident with all models. The model with the best fit included a linear recursive relationship between TNB and the logit of [Formula: see text] of the multiplicative binomial distribution, and it implies that piglet mortality increases with litter size. Estimates of direct effects showed small differences among populations. The analysis of maternal effects indicated that the dams whose mothers were EE had a larger SB, while dams with RR mothers reduced the probability of born dead. The posterior estimates of heterosis suggested a reduction in SB when the sow is crosbred. The multiplicative binomial distribution provides a useful alternative to the binomial distribution when there is overdispersion in the data. Recursive models can be used for modeling non-genetic relationships between traits, even if the phenotypic dependency between traits varies among environments or groups of individuals. Piglet perinatal mortality increased with TNB and is reduced by maternal heterosis.
围产期仔猪死亡率是从经济和动物福利角度考虑养猪生产的一个重要因素；然而，由于其类别性质，死亡率的统计分析很困难。最近的研究表明，对于每个特定仔猪的生存，使用二项式模型和对数方法是合适的，并且性状之间的递归关系对于考虑与其他性状的非遗传关系是有用的。在这项研究中，递归二项式模型在两个方向上进行了扩展：（1）允许个体或杂交组之间性状的递归表型依赖性发生变化；（2）用可乘二项式分布代替二项式分布以说明过度或不足离散。在这项研究中，使用了五个递归可乘二项式模型来获得在伊比利亚猪三个品种（Entrepelado（EE）、Torbiscal（TT）和Retinto（RR））之间的互交杂种参数的估计值。来自 2110 头母猪的记录（10255 条）分布如下：EE（433 条记录，100 头母猪）、ER（2336 条记录，527 头母猪）、ET（942 条记录，177 头母猪）、RE（806 条记录，196 头母猪）、RR（870 条记录，175 头母猪）、RT（2450 条记录，488 头母猪）、TE（193 条记录，36 头母猪）、TR（1993 条记录，359 头母猪）和 TT（232 条记录，68 头母猪）。平均窝产仔数（总产仔数，TNB）和死产仔数（SB）分别为 8.46±2.27 和 0.25±0.72。所有模型都存在过度离散。拟合效果最好的模型包括 TNB 与可乘二项式分布中 [Formula: see text]的对数之间的线性递归关系，这表明仔猪死亡率随窝产仔数的增加而增加。直接效应的估计值显示出种群之间的微小差异。母体效应分析表明，母亲为 EE 的母猪 SB 较大，而 RR 母亲的母猪则降低了产死胎的概率。杂种优势的后验估计表明，当母猪杂交时，SB 会减少。当数据存在过度离散时，可乘二项式分布为二项式分布提供了一个有用的替代方案。递归模型可用于建模性状之间的非遗传关系，即使性状之间的表型依赖性在环境或个体组之间发生变化。围产期仔猪死亡率随 TNB 增加而增加，通过母体杂种优势降低。
