Assessing feed efficiency in beef steers through feeding behavior, infrared thermography and glucocorticoids
Assessing feed efficiency in beef steers through feeding behavior, infrared thermography and glucocorticoids
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DOI：
10.1017/s1751731109991522
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发表时间：
2010-05-01
期刊：
影响因子：
3.6
通讯作者：
Miller, S. P.
中科院分区：
文献类型：
--
作者：
Montanholi, Y. R.;Swanson, K. C.;Miller, S. P.
需要更好地了解调节饲料效率的因素及其作为牛饲料效率预测因子的潜力。因此，三类性状的潜力，即喂养行为特征：每天在喂食器的时间（TF；min/day）、每餐时间（TM；min）、膳食量（MS；g DM）、进食率（ER；g DM/min）、每日进餐次数（NM）和每天到喂食器的次数（VF）；红外（IR）热成像特征（摄氏度）：眼睛（EY）、脸颊（CK）、鼻子（SN）、肋骨（RB）和后部区域（HA）；和糖皮质激素水平：粪便皮质醇代谢物（FCM；ng/g）和血浆皮质醇（PC；ng/ml）作为效率的预测因子，对 91 头公牛（436 × 37 kg）进行了为期 2 年的评估（Y1 = 46；Y2 = 45）。此外，这三个类别中每一个的个体特征被组合起来定义了三个单一特征。使用自动饲喂系统测量玉米青贮饲料和高水分玉米日粮的个体每日采食量。在 140 天的时间里，每 28 天测量一次体重和温度记录图。计算了四种生产性能性状：每日干物质摄入量（DMI）、平均日增重（ADG）、料重比（F:G）和剩余采食量（RFI）。阉牛也分为三个 RFI 类别（低、中和高 RFI）。在摄食行为特征中，MS和ER与所有效率特征相关（范围：0.26至0.75）。与高 RFI 转向器相比，低 RFI（更高效的转向器）具有更小的 MS、更低的 ER 和更少的 VF。效率较低的牛（高 RFI）在夜间比效率较高的牛表现出更多的 VF。效率较高的转向器比效率较低的转向器具有更低的 CK 和 SN 温度（28.1 摄氏度对 29.2 摄氏度和 30.0 摄氏度对 31.2 摄氏度），这表明低 RFI 转向器的能量效率更高。就糖皮质激素而言，PC 与效率特征不相关。相比之下，与效率较低的公牛相比，效率更高的公牛具有更高的 FCM（51.1 比 31.2 ng/g），这表明较高的皮质醇基线与更好的饲料效率相关。对三类性状的总体评估显示，饲喂行为、红外热成像和糖皮质激素分别占与 RFI 相关的总变异的 18%、59% 和 7%。 可用于间接评估牛的饲料效率。其中，红外热成像是筛选牛的饲料效率的最有前途的替代方案。这些发现可能适用于选择计划以及更好地理解与生产绩效相关的生物学基础。
A better understanding of the factors regulating feed efficiency and their potential as predictors of feed efficiency in cattle is needed. Therefore, the potential of three classes of traits, namely, feeding behavior characteristics: daily time at feeder (TF; min/day), time per meal (TM; min), meal size (MS; g DM), eating rate (ER; g DM/min), number of daily meals (NM) and daily visits to the feeder (VF); infrared (IR) thermography traits (degrees C): eye (EY), cheek (CK), snout (SN), ribs (RB) and hind area (HA); and glucocorticoid levels: fecal cortisol metabolites (FCM; ng/g) and plasma cortisol (PC; ng/ml) as predictors of efficiency were evaluated in 91 steers (436 37 kg) over 2 years (Y1 = 46; Y2 = 45). Additionally, the individual traits of each of these three classes were combined to define three single traits. Individual daily feed intake of a corn silage and high-moisture corn-based diet was measured using an automated feeding system. Body weight and thermographs were taken every 28 days over a period of 140 days. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F: G) and residual feed intake (RFI). Steers were also classified into three RFI categories (low-, medium- and high-RFI). Among the feeding behavior characteristics, MS and ER were correlated with all efficiency traits (range: 0.26 to 0.75). Low-RFI (more efficient steers) had smaller MS, lower ER and fewer VF in comparison to high-RFI steers. Less efficient steers (high-RFI) performed more VF during the nocturnal period than more efficient steers. More efficient steers had lower CK and SN temperatures than less efficient steers (28.1 degrees C v. 29.2 degrees C and 30.0 degrees C v. 31.2 degrees C), indicating greater energetic efficiency for low-RFI steers. In terms of glucocorticoids, PC was not correlated with efficiency traits. In contrast, more efficient steers had higher FCM in comparison to less efficient steers (51.1 v. 31.2 ng/g), indicating that a higher cortisol baseline is related to better feed efficiency The overall evaluation of the three classes of traits revealed that feeding behavior, IR thermography and glucocorticoids accounted for 18%, 59% and 7% of the total variation associated with RFI, respectively These classes of traits have usefulness in the indirect assessment of feed efficiency in cattle. Among them, IR thermography was the most promising alternative to screen cattle for this feed efficiency. These findings might have application in selection programs and in the better understanding of the biological basis associated with productive performance.