Kayser W, Hill R A
Department of Animal and Veterinary Science, University of Idaho, Moscow 83844.
J Anim Sci. 2013 Nov;91(11):5492-9. doi: 10.2527/jas.2013-6611. Epub 2013 Aug 29.
The objectives of this study were to examine the growth, DMI, and feeding behaviors of Angus and Hereford bulls; identify the relationships between feeding behaviors and variation in DMI and residual feed intake (RFI); and determine the value of feeding behaviors in predicting DMI. Individual DMI was measured in Angus bulls (n=189; initial BW=427±3.4 kg) and Hereford bulls (n=146; initial BW=411±4.1 kg) fed a grower ration for 71 d in 2009, 78 d in 2010, and 74 d in 2011 using a GrowSafe intake monitoring system. Feeding frequency (FF, meals/d), head down duration (HDD, s/d), head down duration per meal (HDDM, HDD/FF, s/meal), average meal size [AMS, kg/(meal·d)], and feeding rate (FR, g/s) were also measured or calculated using behavior data collected by the GrowSafe system. Ultrasound measures of 12th-rib fat thickness (UFT), longissimus muscle area (ULMA), and intramuscular fat (IMF) were determined during the midtest-weight event of every trial. The data from 3 yr were pooled to generate mean differences between the breeds. Residual feed intake was calculated using a linear regression of DMI on ADG and midtest BW0.75 (MMWT). Animals were classified into 3 RFI groups based on their RFI score as Low (>0.5 SD below the mean), Average (±0.5 SD from the mean), or High RFI (>0.5 SD above the mean). Angus bulls in the Low RFI group consumed 17% (P<0.0001) less DM than the bulls in the High RFI group, while in the Hereford bulls there was a 14% (P<0.0001) difference in DMI between Low and High RFI groups. Significant phenotypic correlations were observed between RFI and DMI (0.83, 0.77), G:F (-0.65, -0.51), HDD (0.41, 0.59), HDDM (0.40, 0.53), AMS (0.52, 0.36), and FR (-0.31, -0.51) in Angus and Hereford bulls, respectively. The HDD, HDDM, and FR were significantly correlated with DMI. The feeding behavior traits, HDD, HDDM, and FR when added to the RFI base model, explained 18, 17, and 13%, respectively, of the variation in DMI not explained by ADG and MMWT in Angus bulls. Similarly, in Hereford bulls, HDD, HDDM, and FR explained 35, 26, and 24%, respectively, of the variation in DMI not explained by ADG and MMWT. These data suggest that feeding behaviors are related to DMI of growing Angus and Hereford bulls.
本研究的目的是考察安格斯牛和赫里福德牛公牛的生长性能、干物质采食量（DMI）及采食行为；确定采食行为与DMI和剩余采食量（RFI）变异之间的关系；并判定采食行为在预测DMI方面的价值。2009年对189头安格斯牛公牛（初始体重=427±3.4千克）和146头赫里福德牛公牛（初始体重=411±4.1千克）饲喂育成期日粮71天，2010年饲喂78天，2011年饲喂74天，采用GrowSafe采食量监测系统测定个体DMI。还利用GrowSafe系统收集的行为数据测量或计算采食频率（FF，次/天）、低头持续时间（HDD，秒/天）、每餐低头持续时间（HDDM，HDD/FF，秒/餐）、平均每餐采食量[AMS，千克/（餐·天）]以及采食速率（FR，克/秒）。在每次试验的中期体重测定时，测定第12肋处脂肪厚度（UFT）、背最长肌面积（ULMA）和肌内脂肪（IMF）的超声测量值。将3年的数据合并以得出品种间的平均差异。使用DMI对平均日增重（ADG）和中期体重0.75次方（MMWT）的线性回归计算剩余采食量。根据RFI分数将动物分为3个RFI组，即低RFI组（高于均值0.5个标准差以上）、平均RFI组（在均值±0.5个标准差范围内）或高RFI组（高于均值0.5个标准差以上）。低RFI组的安格斯牛公牛比高RFI组的公牛少消耗17%（P<0.0001）的干物质，而在赫里福德牛公牛中，低RFI组和高RFI组的DMI差异为14%（P<0.0001）。在安格斯牛和赫里福德牛公牛中，分别观察到RFI与DMI（0.83，0.77）、生长育肥比（G:F）（-0.65，-0.51）、HDD（0.41，0.59）、HDDM（0.40，0.53）、AMS（0.52，0.36）和FR（-0.31，-0.51）之间存在显著的表型相关性。HDD、HDDM和FR与DMI显著相关。在安格斯牛公牛中，将采食行为性状HDD、HDDM和FR添加到RFI基础模型中，分别解释了ADG和MMWT未解释的DMI变异的18%、17%和13%。同样，在赫里福德牛公牛中，HDD、HDDM和FR分别解释了ADG和MMWT未解释的DMI变异的35%、26%和24%。这些数据表明，采食行为与生长中的安格斯牛和赫里福德牛公牛的DMI相关。
