摘要
Feed intake (FI), weight gain (WG), metabolic weight (MW), feed conversion ratio (FCR), residual feed intake calculated by regression (RFI) and feeding standards formulae (RFIS) were recorded on 1481 steers and heifers of tropically adapted and temperate breeds of cattle feedlot finished on a grain based diet for the domestic (liveweight 400 kg), Korean (520 kg) or Japanese (steers only; 600 kg liveweight) markets. Also measured were subcutaneous fat at the rump (P8) and 12/13 rib sites, 12/13 rib eye muscle area and intra-muscular fat (IMF%), time spent eating, eating rate and number of meals per day. Estimated heritabilities of FI, MW, WG, FCR, RFI and RFIS were 0.27, 0.41, 0.23, 0.06, 0.18 and 0.13. RFI and RFIS had very high genetic (0.98) and phenotypic (0.94) correlations, suggesting that they represent very similar traits. RFI had relatively high genetic correlations with rump and rib fat (0.72 and 0.48 adjusted for age; 0.79 and 0.58 adjusted for carcase weight), but lower correlations with IMF% (0.22 and 0.25 adjusted for age and carcase weight, respectively). Selection for lower RFI is therefore possible in feedlot finished cattle, but fatness will also decrease. In this study, selection for reduced fatness was predicted to reduce RFI by more than direct selection. When appropriate, multivariate selection is therefore recommended to achieve increased feed efficiency together with the desired level of fatness, using an index including RFI, on-test weight gain and fat measurements.
There were large breed differences for number of meals per day; Brahman cattle ate more frequently than Belmont Red and Santa Gertrudis breeds which ate more often than temperate breed cattle. Within breeds, there was a tendency for more efficient animals to have fewer meals per day.
摘要译文
饲料摄入量（FI），体重增加（WG），代谢重量（MW），饲料转化率（FCR），通过回归计算的残余采食量（RFI）和饲喂标准公式（RFIS）记录在1481个阉牛和小牛的热带上改良和温带品种的牛饲养场以谷物为基础的饮食，国内（活体重400公斤），韩国（520公斤）或日本（仅限阉牛; 600公斤活重）市场。还测量了臀部（P8）和12/13肋骨部位，12/13肋骨肌肉区域和肌内脂肪（IMF％）的皮下脂肪，进食时间，进食速度和每日进餐次数。 FI，MW，WG，FCR，RFI和RFIS的估计遗传力分别为0.27,0.41,0.23,0.06,0.18和0.13。 RFI和RFIS具有非常高的遗传（0.98）和表型（0.94）相关性，表明它们代表非常相似的性状。 RFI与臀部和肋骨脂肪具有相对较高的遗传相关性（根据年龄调整为0.72和0.48;根据胴体重量调整0.79和0.58，但与IMF％的相关性较低（分别针对年龄和胴体重量调整0.22和0.25）。因此，在饲养场成品牛中可以选择较低的RFI，但脂肪也会减少。在这项研究中，预测减少脂肪的选择比直接选择减少RFI。因此，建议采用多变量选择，以使用包括RFI，测试体重增加和脂肪测量在内的指数，提高饲料效率和所需的肥胖水平。每天的用餐次数存在较大差异;婆罗门牛比Belmont Red和Santa Gertrudis品种吃得更频繁，这些品种比温带品种的牛更常吃。在品种内，有一种趋势是更有效的动物每天少吃饭。
D.L.Robinson[a][b];V.H.Oddy[a][c][1];. Genetic parameters for feed efficiency, fatness, muscle area and feeding behaviour of feedlot finished beef cattle[J]. Livestock Production Science, 2004,90(2-3): 255-270