Department of Animal Sciences, The Ohio State University, Columbus, OH.
Darr College of Agriculture, Missouri State University, Springfield, MO.
J Anim Sci. 2018 Mar 6;96(2):430-443. doi: 10.1093/jas/skx075.
Data were collected from 1953 through 1980 from identical and fraternal twin beef and dairy females born in 1953, 1954, 1959, 1964, and 1969, from crossbred females born as singles in 1974, and their progeny. Numbers of dams that weaned at least one calf and were included in the first analysis were 37, 45, and 56 in the 1964, 1969, and 1974 data sets, respectively. Respective numbers of dams that weaned three calves and were included in a second analysis were 6, 8, 8, 22, 33, and 33 in the 1953, 1954, 1959, 1964, 1969, and 1974 experiments. Individual feed consumption was measured at 28-d intervals from the time females were placed on the experiment at 240 d of age until three calves were weaned or the dams had reached 5 yr of age. Residual feed intake (RFI) and residual BW gain (RG) of heifers that subsequently became dams were determined based on ADG and DMI from 240 d of age to first calving. Various measures of cow efficiency were calculated on either a life cycle or actual lifetime basis using ratios of progeny and dam weight outputs to progeny and dam feed inputs. The correlation between RFI and DMI was large and positive (r = 0.67; P < 0.0001), and RG was highly correlated with ADG (r = 0.75; P < 0.0001). Correlations of RFI with cow efficiency ratios that included harvest weight, carcass weight, or weight of trimmed wholesale cuts as measures of output ranged from -0.05 (P > 0.10) to -0.17 (P < 0.10), indicating that heifers with better (i.e., more negative) RFI values tended to become slightly more efficient cows. Correlations of RG with life cycle and actual lifetime cow efficiency ratios ranged from 0.08 (P > 0.10) to 0.23 (P < 0.05), demonstrating that heifers with better (i.e., more positive) values for RG were somewhat more efficient as cows. The correlations were stronger when cow salvage value was included in the measures of cow efficiency. Correlations of DMI and mid-test metabolic BW (MMW) with life cycle cow efficiency ratios that did not include cow salvage value as output ranged from -0.15 (P < 0.10) to -0.22 (P < 0.01). Correlations of DMI and MMW with actual lifetime cow efficiency ratios varied from -0.20 (P < 0.05) to -0.36 (P < 0.001). Therefore, smaller heifers that consumed less feed had superior cow efficiency ratios. Correlations of RFI with carcass grade, backfat thickness, marbling score, and kidney fat of progeny indicated that heifers with superior RFI would tend to produce leaner offspring.
数据来自于 1953 年至 1980 年间出生于 1953 年、1954 年、1959 年、1964 年和 1969 年的同卵和异卵双胎肉牛和奶牛雌性以及 1974 年作为单胎出生的杂交雌性及其后代。在第一次分析中，至少有一头小牛断奶并被包括在内的母牛头数分别为 1964 年、1969 年和 1974 年数据集中的 37、45 和 56。在第二次分析中，至少有三头小牛断奶并被包括在内的母牛头数分别为 1953 年、1954 年、1959 年、1964 年、1969 年和 1974 年实验中的 6、8、8、22、33 和 33。从雌性在 240 日龄时进入实验到三头小牛断奶或母畜达到 5 岁时，每隔 28 天测量一次个体饲料消耗量。根据 240 日龄至首次产犊的 ADG 和 DMI，确定了随后成为母畜的小母牛的残留饲料摄入量（RFI）和残留 BW 增益（RG）。使用后代和母畜体重产出与后代和母畜饲料投入的比值，在生命周期或实际终身基础上计算了各种牛效率指标。RFI 与 DMI 之间的相关性很大且为正（r=0.67；P<0.0001），而 RG 与 ADG 高度相关（r=0.75；P<0.0001）。RFI 与包括收获体重、胴体体重或修剪后的批发切块重量在内的牛效率比值的相关性范围为-0.05（P>0.10）至-0.17（P<0.10），表明 RFI 值较好（即更负）的小母牛往往更有效地成为奶牛。RG 与生命周期和实际终身牛效率比值的相关性范围为 0.08（P>0.10）至 0.23（P<0.05），表明 RG 值较好（即更正）的小母牛作为奶牛效率更高。当将牛的残值包含在牛效率的度量中时，相关性更强。DMI 和中期代谢 BW（MMW）与不包括牛残值作为产出的生命周期牛效率比值的相关性范围为-0.15（P<0.10）至-0.22（P<0.01）。DMI 和 MMW 与实际终身牛效率比值的相关性范围为-0.20（P<0.05）至-0.36（P<0.001）。因此，饲料消耗量较小的小母牛具有更好的牛效率比值。RFI 与后代的体况等级、背膘厚度、大理石花纹评分和肾脂的相关性表明，具有较好 RFI 的小母牛往往会产生更瘦的后代。
