Centre for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Ontario N1G 2W1, Canada; Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Ontario N1G 2W1, Canada.
Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Ontario N1G 2W1, Canada.
J Dairy Sci. 2020 Feb;103(2):1528-1540. doi: 10.3168/jds.2019-17414. Epub 2019 Dec 16.
A variety of measures are currently used to evaluate feed efficiency in livestock, with some of the most popular being the linear regression of nutrient intake on the various energy sinks of the cohort being evaluated. The adoption of novel on-farm technologies has greatly increased the breadth and depth of data being collected on a daily basis, which creates the opportunity for the implementation of more advanced feed efficiency models. The objectives of the current study were to leverage data collected using high-throughput biometric technologies to evaluate changes of early-lactation feed efficiency on a daily basis and to develop a novel measure of feed efficiency based on the NRC net energy model. Daily records of nutrient intake, fat- and protein-corrected milk yield, body weight, and body condition score were used to model 7 different indices of feed efficiency (gross feed efficiency, return over feed costs, residual feed intake, residual net energy intake, and net energy efficiencies of lactation, maintenance, and body reserve flux) in primiparous Holstein heifers (n = 40) from 0 to 150 d in milk. We observed that feed efficiency was dynamic and fluctuated over the course of the experimental period regardless of the efficiency measure used, but most measures followed similar trends in changes of efficiency on a day-to-day basis. Of the measures evaluated, return over feed costs would be most suited for management purposes due to practicality and simplicity, whereas other measures, such as the efficiency of net energy flux to and from body reserves, present potential targets for inclusion in breeding goals. Net energy efficiency of lactation was estimated to have higher repeatability compared with residual feed or energy intake, which may reduce the time required to estimate whole-lactation efficiency. Because decreased net energy balance was strongly correlated with increased efficiency for all indices evaluated, future work investigating the associations of feed efficiency with the magnitude and duration of negative energy balance is warranted.
目前有多种方法可用于评估家畜的饲料效率，其中一些最常用的方法是线性回归法，即将营养物质摄入量与被评估群体的各种能量消耗源相关联。新型农场技术的采用极大地增加了日常收集数据的广度和深度，这为实施更先进的饲料效率模型创造了机会。本研究的目的是利用高通量生物计量技术收集的数据来评估早期泌乳期的饲料效率变化，并基于 NRC 净能模型开发一种新的饲料效率衡量指标。本研究使用每日的营养物质摄入量、脂肪校正乳产量、体重和体况评分记录来对 7 种不同的饲料效率指标（总饲料效率、饲料成本回报、剩余饲料摄入量、剩余净能摄入量以及泌乳、维持和体储备通量的净能效率）进行建模，共涉及 40 头初产荷斯坦奶牛从 0 到 150 天泌乳期的记录。结果表明，无论使用哪种效率指标，饲料效率都是动态的，并且在整个实验期间都存在波动，但大多数指标的效率变化趋势都具有相似性。在评估的指标中，饲料成本回报由于其实用性和简单性最适合管理目的，而其他指标，如体储备中净能的流入和流出效率，可能成为纳入选育目标的潜在指标。与剩余饲料或能量摄入量相比，泌乳净能效率的重复性更高，这可能会减少估计整个泌乳期效率所需的时间。由于所有评估指标的净能平衡减少与效率提高呈强相关，因此未来研究调查饲料效率与负能平衡的幅度和持续时间的关联是有必要的。
