Teagasc, Moorepark Dairy Production Research Centre, Fermoy, Co Cork, Ireland.
J Anim Sci. 2010 Mar;88(3):885-94. doi: 10.2527/jas.2009-1852. Epub 2009 Dec 4.
No genetic parameters for performance and feed efficiency traits are available for Irish performance-tested bulls. The objective of this study was to determine the phenotypic and genetic variation for feed intake, BW, ADG, and measures of feed efficiency including feed conversion ratio (FCR), relative growth rate, Kleiber ratio, residual BW gain (RG), and residual feed intake (RFI). Observations were available on up to 2,605 bulls for each trait from one test station across 24 yr; breeds included in the analyses were Aberdeen Angus (AN), Charolais (CH), Hereford, Limousin (LI), and Simmental. The test period was at least 70 d. Bulls were individually offered concentrates ad libitum, with a restricted forage allowance. Differences in performance and feed efficiency existed among breeds. For example, AN, on average, ate 0.04 kg of DM/d more than CH but had ADG of 0.14 kg/d less over the 70-d test period. Results showed LI and CH were the most efficient breeds when efficiency was defined as FCR or RFI. When animals were partitioned into groups based on high, medium, or low RFI, the low RFI (i.e., most efficient) group were also the more efficient as defined by RG and FCR. The low RFI group had the same ADG as the medium group and a greater ADG (P < 0.01) than the high group (1.67 vs. 1.66 and 1.63 kg/d); yet they ate 0.67 kg of DM/d less (P < 0.001) than the medium RFI group and 1.22 kg of DM/d less (P < 0.001) than the high RFI (i.e., least efficient) group. Genetic parameters for all performance and efficiency measures were estimated across breeds using linear animal mixed models; heritability estimates for feed efficiency traits ranged from 0.28 +/- 0.06 (RG) to 0.45 +/- 0.06 (RFI). An additional series of analyses included a maternal component in the model; maternal heritability estimates for feed efficiency traits ranged from 0.05 +/- 0.03 (RG) to 0.11 +/- 0.05 (relative growth rate). Genetic correlations between most of the different feed efficiency measures were strong. Results from this study indicate significant genetic differences in performance and some measures of feed efficiency among performance-tested beef bulls.
爱尔兰的性能测试公牛没有表现和饲料效率性状的遗传参数。本研究的目的是确定饲料摄入量、体重、日增重和饲料效率的表型和遗传变异，包括饲料转化率（FCR）、相对生长率、克莱伯比率、残留体重增益（RG）和残留饲料摄入量（RFI）。在 24 年的时间里，每个性状在一个测试站最多可以获得 2605 头公牛的观察值；分析中包括的品种有阿伯丁安格斯（AN）、夏洛来（CH）、赫里福德、利木赞（LI）和西门塔尔。测试期至少为 70 天。公牛自由采食精饲料，限量供应粗饲料。品种之间存在性能和饲料效率的差异。例如，AN 平均每天比 CH 多吃 0.04 公斤 DM，但在 70 天的测试期内 ADG 少 0.14 公斤/天。结果表明，当效率定义为 FCR 或 RFI 时，LI 和 CH 是最有效的品种。当根据高、中、低 RFI 将动物分组时，低 RFI（即最有效）组也具有 RG 和 FCR 定义的效率。低 RFI 组的 ADG 与中 RFI 组相同，比高 RFI 组更高（P < 0.01）（1.67 对 1.66 和 1.63 公斤/天）；然而，它们比中 RFI 组少吃 0.67 公斤 DM（P < 0.001），比高 RFI（即最无效）组少吃 1.22 公斤 DM（P < 0.001）。使用线性动物混合模型在品种间估计所有性能和效率度量的遗传参数；饲料效率性状的遗传力估计值范围为 0.28 +/- 0.06（RG）至 0.45 +/- 0.06（RFI）。一系列额外的分析包括模型中的母体成分；饲料效率性状的母体遗传力估计值范围为 0.05 +/- 0.03（RG）至 0.11 +/- 0.05（相对生长率）。大多数不同饲料效率度量之间的遗传相关性很强。本研究的结果表明，在性能测试的牛肉公牛中，性能和一些饲料效率指标存在显著的遗传差异。
