Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
J Anim Sci. 2013 Sep;91(9):4069-79. doi: 10.2527/jas.2012-6197. Epub 2013 Jul 3.
Residual feed intake (RFI) is commonly used as a measure of feed efficiency at a given level of production. A total of 16,872 pigs with their pedigree traced back as far as possible was used to estimate genetic parameters for RFI, growth performance, food conversion ratio (FCR), body conformation, and feeding behavior traits in 3 Danish breeds [Duroc (DD), Landrace (LL), and Yorkshire (YY)]. Two measures of RFI were considered: residual feed intake 1 (RFI1) was calculated based on regression of daily feed intake (DFI) from 30 to 100 kg on initial test weight and ADG from 30 to 100 kg (ADG2). Residual feed intake 2 (RFI2) was as RFI1, except it was also regressed with respect to backfat (BF). The estimated heritabilities for RFI1 and RFI2 were 0.34 and 0.38 in DD, 0.34 and 0.36 in LL, and 0.39 and 0.40 in YY, respectively. The heritabilities ranged from 0.32 (DD) to 0.54 (LL) for ADG2, from 0.54 (DD) to 0.67 (LL) for BF, and from 0.13 (DD) to 0.19 (YY) for body conformation. Feeding behavior traits including DFI, number of visits to feeder per day (NVD), total time spent eating per day (TPD), feed intake rate (FR), feed intake per visit (FPV), and time spent eating per visit (TPV) were moderately to highly heritable. Residual feed intake 2 was genetically independent of ADG2 and BF in all breeds, except it had low genetic correlation to ADG2 in YY (0.2). Residual feed intake 1 was also genetically independent of ADG2 in DD and LL. Both RFI traits had strong genetic correlations with DFI (0.85 to 0.96) and FCR (0.76 to 0.99). They had low or no genetic correlations with feeding behavior traits. Unfavorable genetic correlations were found between ADG2 and both BF and DFI. Among feeding behavior traits, DFI had low genetic correlations to other traits in all breeds. High and negative genetic correlations were also found between TPD with FR (-0.79 in YY to -0.88 in DD), NVD, and TPD (-0.91 in DD to -0.94 in YY) and between NVD and FPV (-0.83 in DD to -0.91 in YY) in all breeds. The genetic trend for feed efficiency was favorable in all breeds regardless of the definition of feed efficiency used. In summary, RFI1 and RFI2 were heritable and selection for reduced RFI2 can be performed without adversely affecting ADG and BF and could replace FCR in the selection index for the Danish pig breeds. Selection could also be based on RFI1 for breeds with fewer concerns about a negative effect of BF or for breeds that do not have BF records.
残余采食量（RFI）通常用作特定生产水平下饲料效率的衡量标准。利用丹麦 3 个品种[杜洛克（DD）、长白猪（LL）和约克夏猪（YY）]的 16872 头可追溯至尽可能远的系谱猪，估计 RFI、生长性能、饲料转化率（FCR）、体况和采食行为性状的遗传参数。考虑了两种 RFI 度量方法：残留采食量 1（RFI1）是根据 30 至 100 公斤体重时的每日采食量（DFI）回归与初始测试体重和 30 至 100 公斤体重时的平均日增重（ADG2）之间的关系计算得出的。残留采食量 2（RFI2）与 RFI1 相同，只是它也与背膘（BF）进行了回归。DD 中的 RFI1 和 RFI2 的估计遗传力分别为 0.34 和 0.38，LL 中的分别为 0.34 和 0.36，YY 中的分别为 0.39 和 0.40。ADG2 的遗传力范围为 0.32（DD）至 0.54（LL），BF 的遗传力范围为 0.54（DD）至 0.67（LL），体况的遗传力范围为 0.13（DD）至 0.19（YY）。包括 DFI、每日采食次数（NVD）、每日采食总时间（TPD）、采食率（FR）、每次采食量（FPV）和每次采食时间（TPV）在内的采食行为性状具有中等至高度的遗传力。RFI2 在所有品种中均与 ADG2 和 BF 遗传独立，除了在 YY 中与 ADG2 的遗传相关性较低（0.2）。DD 和 LL 中的 RFI1 也与 ADG2 遗传独立。这两个 RFI 性状与 DFI（0.85 至 0.96）和 FCR（0.76 至 0.99）具有很强的遗传相关性。它们与采食行为性状的遗传相关性较低或没有。ADG2 与 BF 和 DFI 之间存在不利的遗传相关性。在采食行为性状中，DFI 在所有品种中与其他性状的遗传相关性均较低。在所有品种中，TPD 与 FR（YY 中的-0.79 至 DD 中的-0.88）、NVD 和 TPD（DD 中的-0.91 至 YY 中的-0.94）和 NVD 与 FPV（DD 中的-0.83 至 YY 中的-0.91）之间也存在高负遗传相关性。无论使用哪种饲料效率定义，所有品种的饲料效率遗传趋势均为有利。总之，RFI1 和 RFI2 是可遗传的，选择降低 RFI2 可以在不影响 ADG 和 BF 的情况下进行，并且可以替代丹麦猪品种选择指数中的 FCR。对于较少关注 BF 负面影响的品种，或者对于没有 BF 记录的品种，也可以基于 RFI1 进行选择。
