Zamani Pouya
Department of Animal Science,Faculty of Agriculture,Bu-Ali Sina University,Iran.
J Dairy Res. 2017 Aug;84(3):248-253. doi: 10.1017/S0022029917000395.
Traditional ratio measures of efficiency, including feed conversion ratio (FCR), gross milk efficiency (GME), gross energy efficiency (GEE) and net energy efficiency (NEE) may have some statistical problems including high correlations with milk yield. Residual energy intake (REI) or residual feed intake (RFI) is another criterion, proposed to overcome the problems attributed to the traditional ratio criteria, but it does not account for production or intake levels. For example, the same REI value could be considerable for low producing and negligible for high producing cows. The aim of this study was to propose a new measure of efficiency to overcome the problems attributed to the previous criteria. A total of 1478 monthly records of 268 lactating Holstein cows were used for this study. In addition to FCR, GME, GEE, NEE and REI, a new criterion called proportional residual energy intake (PREI) was calculated as REI to net energy intake ratio and defined as proportion of net energy intake lost as REI. The PREI had an average of -0·02 and range of -0·36 to 0·27, meaning that the least efficient cow lost 0·27 of her net energy intake as REI, while the most efficient animal saved 0·36 of her net energy intake as less REI. Traditional ratio criteria (FCR, GME, GEE and NEE) had high correlations with milk and fat corrected milk yields (absolute values from 0·469 to 0·816), while the REI and PREI had low correlations (0·000 to 0·069) with milk production. The results showed that the traditional ratio criteria (FCR, GME, GEE and NEE) are highly influenced by production traits, while the REI and PREI are independent of production level. Moreover, the PREI adjusts the REI magnitude for intake level. It seems that the PREI could be considered as a worthwhile measure of efficiency for future studies.
传统的效率比率衡量指标，包括饲料转化率（FCR）、总产奶效率（GME）、总能效率（GEE）和净能效率（NEE），可能存在一些统计问题，包括与产奶量高度相关。剩余能量摄入量（REI）或剩余饲料摄入量（RFI）是另一种标准，旨在克服传统比率标准所带来的问题，但它没有考虑生产或摄入量水平。例如，相同的REI值对于低产奶牛可能相当可观，而对于高产奶牛则可忽略不计。本研究的目的是提出一种新的效率衡量指标，以克服先前标准所带来的问题。本研究使用了268头泌乳荷斯坦奶牛的1478条月度记录。除了FCR、GME、GEE、NEE和REI外，还计算了一个名为比例剩余能量摄入量（PREI）的新标准，即REI与净能量摄入量的比率，并定义为作为REI损失的净能量摄入量的比例。PREI的平均值为 -0·02，范围为 -0·36至0·27，这意味着效率最低的奶牛将其净能量摄入量的0·27作为REI损失掉，而效率最高的奶牛则通过较少的REI节省了其净能量摄入量的0·36。传统比率标准（FCR、GME、GEE和NEE）与牛奶和脂肪校正牛奶产量高度相关（绝对值从0·469至0·816），而REI和PREI与产奶量的相关性较低（0·000至0·069）。结果表明，传统比率标准（FCR、GME、GEE和NEE）受生产性状的影响很大，而REI和PREI与生产水平无关。此外，PREI针对摄入量水平调整了REI的幅度。看来，PREI可以被视为未来研究中一个有价值的效率衡量指标。
