Residual feed intake (sometimes shortened in literature to RFI) is a resource allocation theory index[clarification needed (what is a "resource allocation theory index"?)] used to calculate the feed efficiency of growing cattle. It was developed by Robert M. Koch in 1963 as an answer to the difficulties of using a feed conversion ratio to compare individual animals.[1] Effective use of RFI data can greatly improve beef cattle farm profits.[2] This approach is based on regression models developed for determining efficiency of feed use for weight gain during a standardized growth trial in growing beef cattle.[3]
It was inspired by Koch's observations of the differences in how a maintained body weight and an increasing body weight affect the feeding of cattle. His research suggested that feed intake could be broken into two parts:
The expected feed intake for the animal's level of production.
The residual portion between the amount of feed the animal is expected to eat, and what the animal actually eats.[2]
Through the use of these two items, animals that deviate from the expected feed intake, either by eating more than or less than what's expected of them, can be identified and managed as the farmer sees fit. Because feed intake is heritable, knowing the RFI index of an animal is also useful when breeding.[2] By selecting animals with the aim to reduce RFI, farmers can breed animals that eat less but continue at the same rate of production.[1]
There is no phenotype link between RFI and the characteristics used to calculate expected feed intake, which allows for the comparison of animals who function at differing production numbers. This has led some authors to believe that RFI is representative of individual differences in the metabolic processes of the animals. For example, one study shows that the amount of feed a Hereford bull requires to maintain a kilogram of body weight is closely related to genetic variation in its RFI. Similarly, in laying hens, variation in RFI is directly linked to variations in maintenance energy expenditure.[2]
^ abSainz, Roberto D.; & Paulino, Pedro V.(2004). Residual Feed Intake. UC Davis: Sierra Foothill Research and Extension Center
^ abcdR.M. Herd (2009). "Residual Feed Intake". In Wendy M. Rauw (ed.). Resource Allocation Theory Applied to Farm Animal Production. CABI. pp. 89–109. ISBN 978-1-84593-436-1. Retrieved 10 July 2013.
^Connor, E. E. (2015-03-01). "Invited review: Improving feed efficiency in dairy production: challenges and possibilities*". Animal. 9 (3): 395–408. doi:10.1017/S1751731114002997. ISSN 1751-7311. PMID 25482927.
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Residualfeedintake (sometimes shortened in literature to RFI) is a resource allocation theory index[clarification needed (what is a "resource allocation...
more to feed; instead residualfeedintake (RFI) is used which is independent of size. RFI uses for output the difference between actual intake and predicted...
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engines is used. The final part of the intake manifold is an air sleeve that feeds the intake ports. The intake ports are placed at a horizontal angle...
sugar syrup which is filtered and then passed over carbon to remove any residual colour. The sugar syrup is then concentrated by boiling under a vacuum...
must be replaced. As noted earlier, the feeding of the low-oxygen exhaust gas into the diesel engine's air intake engenders lower combustion temperatures...
prepared before consumption, as improper preparation can leave enough residual cyanide to cause cyanide poisoning. The more toxic varieties of cassava...
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classified as paranoid, disorganized, catatonic, undifferentiated, and residual – were difficult to distinguish and are no longer recognized as separate...
of multiplying. Yeast living at that moment can continue fermenting any residual sugar into CO2 and alcohol, but when they die, no new yeast will be present...
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processing the soybean crop. Soybean is the most important protein source for feed farm animals (that in turn yields animal protein for human consumption)....
toxicity concerns; and the last has been associated with eutrophication. Residual concentrations of biocides and corrosion inhibitors are of potential concern...
typically seen). Initial symptoms include feeding intolerance and failure to thrive, increased gastric residuals, abdominal distension, and bloody stools...
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aspirator. An ejector operates on similar principles to create a vacuum feed connection for braking systems etc. The motive fluid may be a liquid, steam...
recovery of N in the above-ground plant in the first year. There is some residual benefit of fertilizers as the crops take up a small amount of the nutrients...
pharaoh ants to scatter and colonies to split, although non-repellent residual insecticides have been reported to be effective. The recommended method...
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