The Poultry Bulletin - - FRONT PAGE - By Loutjie Dunn

In a coun­try con­stantly un­der pres­sure from cheap im­ports and high feed prices, it’s no sur­prise that feed con­ver­sion (FCR) al­ways stays a fo­cus point. FCR can be cal­cu­lated with dif­fer­ent equa­tions. We need to be aware of the dif­fer­ences be­tween the equa­tions, as well as the real mean­ing of the dif­fer­ent con­stituents used in the equa­tions.

Sci­en­tific Cal­cu­la­tion

FCR = Feed con­sumed ÷ growth = kg feed/kg growth.

Feed con­sumed is the ac­tual feed in­take of the birds over a spe­cific pe­riod and growth the ac­tual growth (gain in live weight) mea­sured over the same pe­riod.

Com­mer­cial Cal­cu­la­tion

FCR = Feed used ÷ live weight = kg feed/kg live weight.

Feed used is the dif­fer­ence be­tween feed de­liv­ered and feed in stock at the end of the grow­ing cy­cle and live weight is mostly the av­er­age weight of the birds (empty crop) de­liv­ered at the abat­toir.

It’s im­por­tant to re­alise that feed used in­cludes feed con­sumed, feed wastage and even per­haps theft, while growth is mostly mea­sured as the in­crease in live weight, weigh­ing birds with full crops com­pared to the empty crop live weight as re­ceived at the abat­toir.

It’s al­ways good to use breed stan­dard as a bench­mark al­though many pro­duc­ers don’t want to re­fer to the breed stan­dards. Keep in mind that the breed stan­dard FCR is cal­cu­lated as a com­bi­na­tion of the sci­en­tific and com­mer­cial equa­tion, with feed in­take (not feed used) and live weight be­ing used. The live weight used is full crop and this cal­cu­la­tion also does not take into ac­count any mor­tal­ity. The live weight used as a di­vider is close to ge­netic po­ten­tial of the bird and all of the above re­sult in a fairly low FCR com­pared to com­mer­cial fig­ures. The im­por­tant as­pect is how­ever the trend as can be seen in Fig­ure 1 that clearly shows FCR is get­ting worse as the birds get older.

Op­ti­mum FCR will have a dif­fer­ent mean­ing for dif­fer­ent peo­ple. For some it might be the low­est FCR pos­si­ble and for oth­ers it might be the FCR where feed

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