Division of Animal Sciences, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2010 Mar;88(3):1108-24. doi: 10.2527/jas.2008-1378. Epub 2009 Oct 23.
Accurate voluntary feed intake (VFI) prediction is critical to the productivity and profitability of ruminant livestock production systems. Simple empirical models have been used to predict VFI for decades, but they are inflexible, restrictive, and poorly accommodate many feeding conditions, such as those of developing countries. We have developed a mechanistic model to predict VFI over a range of forage diets (low- and high-quality grasses and legumes) by wild and domestic ruminants of varying physiological states (growth, lactation, gestation, nonproductive). Based on chemical reactor theory, the model represents the reticulorumen, large intestine, and blood plasma as continuous stirred-tank reactors and the small intestine as a plug flow reactor. Predicted VFI is that which 1) fulfills an empirical relationship between chemostatic and distention feedback observed in the literature, and 2) leads to steady-state conditions. Agreement between observed and actual VFI was great (generally R(2) >0.9, root mean square prediction error <1.4 kg/d, CV <25%). Root mean square prediction error for our model was only 67% that of the Beef NRC (2000) model, the leading empirical prediction system for cattle. Together, these results demonstrate that our model can predict ruminant VFI more broadly and accurately than prior methods and, by consequence, serve as a crucial tool to ruminant livestock production systems.
准确预测动物的自愿采食量（VFI）对于反刍动物生产系统的生产力和盈利能力至关重要。几十年来，人们一直使用简单的经验模型来预测 VFI，但这些模型缺乏灵活性、限制性强，且无法很好地适应许多饲养条件，例如发展中国家的饲养条件。我们开发了一种机制模型，可以预测不同生理状态（生长、泌乳、妊娠、非生产性）的野生和家养反刍动物在一系列饲草日粮（低质量和高质量的草和豆科植物）下的 VFI。该模型基于化学反应器理论，将瘤胃、大肠和血浆表示为连续搅拌罐反应器，将小肠表示为活塞流反应器。预测的 VFI 是满足文献中观察到的化学平衡和膨胀反馈之间的经验关系的 VFI，并且 2）导致稳态条件。观察到的和实际的 VFI 之间的一致性非常好（通常 R²>0.9，均方根预测误差<1.4kg/d，变异系数<25%）。与 Beef NRC（2000）模型（牛的领先经验预测系统）相比，我们的模型的均方根预测误差仅为其 67%。总之，这些结果表明，我们的模型可以比以前的方法更广泛和准确地预测反刍动物的 VFI，因此是反刍动物生产系统的重要工具。
