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In animal husbandry, feed conversion ratio (FCR), feed conversion rate, or feed conversion efficiency (FCE), is a measure of an animal's efficiency in converting feed mass into increases of the desired output. For dairy cows, for example, the output is milk,〔Dairy Australia (Feed Conversion Efficiency )〕 whereas animals raised for meat – such as beef cows,〔Dan Shike, University of Illinois (Beef Cattle Feed Efficiency )〕 pigs,〔( Pork production )〕 chickens,〔(Feed conversion rate for chickens )〕 and fish〔USAID (Technical Bulletin #07: Feed Conversion Ratio (FCR): How to calculate it and how it is used )〕 – the output is the mass gained by the animal. Specifically FCR is the mass of the food eaten divided by the output, all over a specified period. "Efficiency" is customarily expressed as the ratio of useful output to input.〔See, for example, definition 2a of "efficiency" at http://education.yahoo.com/reference/dictionary/entry/efficiency〕 Thus, although FCR is commonly expressed as the ratio of feed mass input to body mass output, one sometimes sees "feed conversion efficiency" (FCE) figures, i.e. kg body mass gain per kg feed intake (or, in the case of dairy animals, kg milk solids per kg feed intake). Being a ratio, FCR is dimensionless, i.e. there are no measurement units associated with FCR. ==Factors affecting FCR== FCR a function of the animal's genetics and age, the quality of the feed, and the conditions in which the animal is kept.〔 As a rule of thumb, the daily FCR is low for young animals (when relative growth is large) and increases for older animals (when relative growth tends to level out). Although FCR is commonly calculated using feed dry mass, it is sometimes calculated on an as-fed wet mass basis,〔Snowder, G. D. and L. D. Van Vleck. 2003. Estimates of genetic parameters and selection strategies to improve the economic efficiency of postweaning growth in lambs. J. Anim. Sci. 81: 2704-2713〕 (or in the case of grains and oilseeds, sometimes on a wet mass basis at standard moisture content), with feed moisture resulting in higher ratios. In cold weather, metabolizable energy requirements for warmth〔National Research Council (Subcommittee on Environmental Stress). 1981. Effect of environment on nutrient requirements of domestic animals. National Academy Press, Washington. 168 pp.〕 may result in less net energy of gain obtained from feed. Thus, when communicating FCR data for a species, it can be desirable to specify feed moisture content and provide information regarding breed, age, feed composition, and environmental conditions under which the ratio applies, to facilitate data interpretation. Cold-blooded organisms expend fewer calories per unit mass. Fish are a common example of cold-blooded livestock. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「feed conversion ratio」の詳細全文を読む スポンサード リンク
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