Abstract

Precise techniques to estimate feed intake by ruminants are critical to enhance feed efficiency and to reduce greenhouse gas emissions and nutrient losses to the environment. Using a meta-analysis, we evaluated the accuracy of the n-alkane technique to predict feed intake in cattle and sheep and assessed the relationships between feed intake and fecal recovery (FR) of n-alkanes. The database was composed of 28 studies, including 129 treatments (87 and 42 for cattle and sheep, respectively) and 402 animals (232 cattle and 170 sheep) fed at troughs, from published studies. Relationships between observed (in vivo measurement) and predicted feed intake by C31:C32 and C32:C33 n-alkane pairs were evaluated by regression. Meta-regression addressed the relationships between the difference in FR of n-alkane pairs and the error in intake estimation, as well as the amount and duration of C32 n-alkane dosing. Regression of observed intake on n-alkane-based estimates revealed good relationships in cattle (adjusted R² = 0.99 for C31:C32, and adjusted R² = 0.98 for C32:C33; P < 0.0001) and in sheep (adjusted R² = 0.94 for C31:C32, and adjusted R² = 0.96 for C32:C33; P < 0.0001). FR of natural n-alkanes showed a coefficient of variation of about 15% and 16% for C31 and C33, respectively, in cattle. In sheep, the coefficient of variation was 8% and 14% for C31 and C33, respectively. The relationships between the difference of FR of n-alkane pairs and the error in feed intake estimation in cattle were characterized by an adjusted R² = 0.83 for C31:C32 (P < 0.0001) and adjusted R² = 0.93 for C32:C33 (P < 0.0001). In sheep, they were characterized by an adjusted R² = 0.69 for C31:C32 (P < 0.001) and adjusted R² = 0.76 for C32:C33 (P < 0.001). The n-alkane technique provided the reliability for estimating feed intake in cattle and sheep in barn experiments. The present meta-analysis demonstrated that without correction for differences in FR of n-alkane pairs, deviation in feed intake prediction would occur. However, further research is necessary to determine the relationship between the n-alkane dosing procedure (daily amount and duration of dosing) and FR of n-alkane.

中文翻译：

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使用正构烷烃估算反刍动物的采食量：荟萃分析。

摘要

估算反刍动物采食量的精确技术对于提高饲料效率和减少温室气体排放和养分对环境的损失至关重要。我们使用荟萃分析评估了正构烷烃技术预测牛和羊采食量的准确性，并评估了采食量与正构烷烃粪便回收率 ( FR )之间的关系。该数据库由 28 项研究组成，包括来自已发表研究的 129 项处理（牛和羊分别为 87 和 42 项）和 402 只动物（232 只牛和 170 只绵羊）在低谷喂养。通过 C31:C32 和 C32:C33 观察到的（体内测量）和预测的采食量之间的关系n-烷烃对通过回归评估。元回归解决了正构烷烃对的FR 差异与摄入量估计误差以及 C32正构烷烃剂量和持续时间之间的关系。观察到的摄入量对基于正烷烃的估计的回归揭示了牛（C31:C32调整后的R ² = 0.99 ，C32:C33调整后的R ² = 0.98；P < 0.0001）和绵羊（调整后的R ² = C31:C32为 0.94，C32:C33调整后的R ² = 0.96；P < 0.0001)。自然n的FR在牛中，α-烷烃的 C31 和 C33 的变异系数分别约为 15% 和 16%。在绵羊中，C31 和 C33 的变异系数分别为 8% 和 14%。正构烷烃对的 FR 差异与牛采食量估计误差之间的关系的特征在于，C31:C32调整后的R ² = 0.83（P < 0.0001），C32:C33调整后的R ² = 0.93（P < 0.0001)。在绵羊中，C31:C32的调整R ² = 0.69 ( P < 0.001) 和C32:C33 的调整R ² = 0.76 ( P < 0.001)。这正构烷烃技术为估算牛和羊在牛舍实验中的采食量提供了可靠性。本荟萃分析表明，如果不对正构烷烃对的FR 差异进行校正，就会出现采食量预测的偏差。然而，需要进一步研究以确定正构烷烃的给药程序（每日给药量和给药持续时间）与正构烷烃的FR 之间的关系。