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Table 4 Expected responses to direct selection on excretion traits or on indirect selection on digestibility (AMEn and CDUDM) and on feed efficiency (FCR and RFI), supposing that selection intensity was 1 for all traits.

From: Improving the efficiency of feed utilization in poultry by selection. 2. Genetic parameters of excretion traits and correlations with anatomy of the gastro-intestinal tract and digestive efficiency

   Selection on
Response1 Direct AMEn CDUDM FCR RFI
CDU-DM 0.300 0.297 0.300 -0.246 -0.238
FEW/BW 0.090 -0.159 -0.154 0.136 0.185
DEW/BW 0.200 -0.225 -0.228 0.189 0.267
FEW/FI 0.170 -0.149 -0.145 0.144 0.106
WE 0.130 0.091 0.077 -0.045 -0.037
NE/NI 0.290 -0.292 -0.295 0.234 0.135
PE/PI 0.220 -0.164 -0.175 0.142 0.025
NE/PE 0.180 -0.195 -0.202 0.171 0.086
  1. Responses are expressed in phenotypic standard deviations of the trait.
  2. 1AMEn, apparent metabolisable energy corrected for zero nitrogen balance; CDUDM, coefficient of digestive use of dry matter; FCR, feed conversion ratio; RFI, residual feed intake; FEW/BW, DEW/BW, fresh and dry excreta weight relative to body weight at 23 d; FEW/FI, fresh excreta weight relative to feed intake; WE, water content of excreta; NE/NI, PE/PI, ratio of nitrogen and phosphorus excretion to intake; NE/PE, ratio of nitrogen to phosphorus excretion