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Table 1 Body composition, metabolic rate (RMR) and oxidative damage (ROMs) of breeding and non-breeding females

From: Artificial selection reveals the energetic expense of producing larger eggs

Trait Breeding Non Breeding t df P
Generation 4
Body Mass
 Total Body Mass (g) 288 ± 35 258 ± 28 2.84 10.90 0.016
 Non-Repro. Mass (g) 262 ± 33 258 ± 28 0.36 11.07 0.724
Body Size
 Tarsus Length (mm) 40.0 ± 1.4 39.8 ± 1.1 0.38 12.09 0.712
Reproductive and Associated Organs
 Repro. Organs (g) 15.18 ± 1.73 0.31 ± 0.12 39.30 8.36 <0.001
 Liver (g) 7.98 ± 1.06 4.66 ± 0.80 9.78 9.60 <0.001
Protein and Lipid Reserves
 Pectoral Muscles (g) 51.85 ± 7.53 51.38 ± 4.67 0.08 14.43 0.939
 Body Fat (g) 4.96 ± 3.00 8.59 ± 3.94 3.29 21.45 0.003
Generation 5
 Body Mass (g)1 254 ± 20 240 ± 17 4.20 28 <0.001
 RMR (mL O2 min−1) 6.01 ± 0.67 3.52 ± 0.37 22.73 28 <0.001
 ROMs (mM H2O2) 0.882 ± 0.263 0.801 ± 0.228 1.22 27 0.232
  1. Means ± SD are shown. In generation 4, females were measured once, either in breeding (N = 65) or in non-breeding (N = 10) condition. In generation 5, females (N =29) were measured twice, once in breeding and once in non-breeding condition. Repro. is abbreviation for Reproductive. Significant results are displayed in bold
  2. 1The difference in body mass between the two states is less than in generation 4 due to measuring the birds at different times of day (here the majority of females had already laid an egg)