Cecchinato A, Bonfatti V, Gallo L, Carnier P
Department of Animal Science, University of Padova, Legnaro, PD, Italy.
J Anim Sci. 2008 Oct;86(10):2486-95. doi: 10.2527/jas.2007-0825. Epub 2008 May 9.
The aim of this study was to investigate piglet preweaning survival and its relationship with a total merit index (TMI) used for selection of Large White terminal boars for dry-cured ham production. Data on 13,924 crossbred piglets (1,347 litters), originated by 189 Large White boars and 328 Large White-derived crossbred sows, were analyzed under a frailty proportional hazards model, assuming different baseline hazard functions and including sire and nursed litter as random effects. Estimated hazard ratios (HR) indicated that sex, cross-fostering, year-month of birth, parity of the nurse sow, size of the nursed litter, and class of TMI were significant effects for piglet preweaning survival. Female piglets had less risk of dying than males (HR = 0.81), as well as cross-fostered piglets (HR = 0.60). Survival increased when piglets were nursed by sows of third (HR = 0.85), fourth (HR = 0.76), and fifth (HR = 0.79) parity in comparison with first and second parity sows. Piglets of small (HR = 3.90) or very large litters (HR >1.60) had less chance of surviving in comparison with litters of intermediate size. Class of TMI exhibited an unfavorable relationship with survival (HR = 1.20 for the TMI top class). The modal estimates of sire variance under different baseline hazard functions were 0.06, whereas the variance for the nursed litter was close to 0.7. The estimate of the nursed litter effect variance was greater than that of the sire, which shows the importance of the common environment generated by the nurse sow. Relationships between sire rankings obtained from different survival models were high. The heritability estimate in equivalent scale was low and reached a value of 0.03. Nevertheless, the exploitable genetic variation for this trait justifies the inclusion of piglet preweaning survival in the current breeding program for selection of Large White terminal boars for dry-cured ham production.
本研究的目的是调查仔猪断奶前的存活率及其与用于选择大白终端公猪进行干腌火腿生产的总性能指数（TMI）之间的关系。对13924头杂种仔猪（1347窝）的数据进行了分析，这些仔猪由189头大白公猪和328头大白杂交母猪繁殖而来，在脆弱比例风险模型下进行分析，假设不同的基线风险函数，并将父系和哺育窝作为随机效应。估计的风险比（HR）表明，性别、交叉寄养、出生年月、哺育母猪的胎次、哺育窝的大小以及TMI类别对仔猪断奶前的存活有显著影响。雌性仔猪死亡风险低于雄性仔猪（HR = 0.81），交叉寄养的仔猪也是如此（HR = 0.60）。与第一胎和第二胎母猪哺育的仔猪相比，由第三胎（HR = 0.85）、第四胎（HR = 0.76）和第五胎（HR = 0.79）母猪哺育的仔猪存活率更高。与中等大小窝的仔猪相比，小窝（HR = 3.90）或非常大窝的仔猪存活机会较小。TMI类别与存活率呈不利关系（TMI顶级类别HR = 1.20）。在不同基线风险函数下，父系方差的模态估计值为0.06，而哺育窝的方差接近0.7。哺育窝效应方差的估计值大于父系方差，这表明哺育母猪产生的共同环境的重要性。从不同存活模型获得的父系排名之间的相关性很高。等效尺度下的遗传力估计值较低，为0.03。然而，该性状可利用的遗传变异证明将仔猪断奶前存活率纳入当前用于选择大白终端公猪进行干腌火腿生产的育种计划是合理的。
