INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
J Anim Sci. 2012 Apr;90(4):1097-108. doi: 10.2527/jas.2011-4515. Epub 2011 Nov 18.
Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.
残留采食量（RFI）已被探索作为替代饲料转化率的选择标准，以捕捉未被预期生产和维持需求解释的采食量部分。选择实验发现，生长猪的低 RFI 与体脂减少和采食量减少有关。选择饲料转化率也会降低母猪的食欲和体脂，这与增加生产力一起，被认为是母猪终生性能的障碍。我们研究的目的是推导出哺乳期母猪 RFI（SRFI）的方程，并评估生长期间 RFI 选择对哺乳期母猪性状的影响。数据来自于在纯大白猪中选择了 7 个世代的低生长 RFI 和高生长 RFI 的 2 个分歧系。RFI 是在候选选择猪（1065 头猪）上测量的，并且有 480 头母猪的性能数据，它们的产仔数从 1 到 3 窝（1071 窝）。测量的性状包括母猪每日采食量（SDFI）；母猪在分娩前和断奶时的 BW 和身体成分（28.4±1.7d）；总出生仔猪数、活仔数和断奶时的成活率；窝重、平均仔猪 BW 和出生时、21 日龄（当开始提供乳猪料时）和断奶时仔猪 BW 的窝内 SD。母猪 RFI 定义为观察到的 SDFI 与母猪维持和生产所需 SDFI 之间的差异。每日生产需求通过窝产仔数和每日窝增重以及母猪体储备的每日变化来量化。SRFI 占 SDFI 表型变异的 24%。RFI 和 SRFI 的遗传估计值均为 0.14。RFI 和 SRFI 之间的遗传相关性为 0.29±0.23。RFI 与母猪性状的遗传相关性为低到中等，与选择反应一致；生长期间选择低 RFI 会降低 SDFI，增加仔猪数和窝生长，但也会增加体储备的动员。没有发现对再配种性能的影响。以前在生长过程中选择时观察到的代谢变化可能解释了低 RFI 母猪效率提高的部分原因，降低了基础代谢率，并有利于资源快速分配到哺乳期。我们建议将 SRFI 作为 SDFI 的替代指标，以选择在哺乳期需求减少的高效母猪。
