High School of Agricultural Sciences, University of Antananarivo, 101 Antananarivo, Madagascar.
North Florida Research and Education Center, University of Florida, Marianna, FL.
J Anim Sci. 2020 Oct 1;98(10). doi: 10.1093/jas/skaa304.
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.
精确的反刍动物采食量估计技术对于提高饲料效率、减少温室气体排放和养分损失到环境中至关重要。我们使用荟萃分析评估了 n-烷烃技术预测牛和羊采食量的准确性，并评估了采食量与 n-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 129 个处理（牛 87 个，羊 42 个）和 402 个动物（牛 232 个，羊 170 个）在槽中进行，这些数据来自已发表的研究。通过回归评估了观察到的（体内测量）和通过 C31：C32 和 C32：C33 n-烷烃对预测的采食量之间的关系。元回归解决了 n-烷烃对之间 FR 差异与摄入估计误差以及 C32 n-烷烃剂量的数量和持续时间之间的关系。观察到的摄入量与基于 n-烷烃的估计值的回归显示出牛（C31：C32 的调整后的 R2 = 0.99，C32：C33 的调整后的 R2 = 0.98；P < 0.0001）和羊（C31：C32 的调整后的 R2 = 0.94，C32：C33 的调整后的 R2 = 0.96；P < 0.0001）之间的良好关系。牛中天然 n-烷烃的 FR 变异系数分别约为 C31 和 C33 的 15%和 16%。在绵羊中，C31 和 C33 的变异系数分别为 8%和 14%。牛中 n-烷烃对之间 FR 差异与饲料摄入量估计误差之间的关系特征为 C31：C32 的调整后的 R2 = 0.83（P < 0.0001）和 C32：C33 的调整后的 R2 = 0.93（P < 0.0001）。在绵羊中，它们的特征为 C31：C32 的调整后的 R2 = 0.69（P < 0.001）和 C32：C33 的调整后的 R2 = 0.76（P < 0.001）。n-烷烃技术为牛和羊在畜舍实验中估计采食量提供了可靠性。本荟萃分析表明，如果不校正 n-烷烃对之间 FR 的差异，将发生饲料摄入量预测的偏差。然而，还需要进一步研究以确定 n-烷烃给药程序（每日剂量和持续时间）与 n-烷烃 FR 之间的关系。
