Formulation and measured nutrient composition of experimental starch (SD) and fat diet (FD).

1<p>Starch diet.</p>2<p>Fat diet.</p

Osmolality of chyme [mOsm kg⁻¹]

<p>(<b>Means±SE</b>)<b>.</b> Measured in the stomach (A), proximal intestine (B), mid intestine (C) and distal intestine (D) of African catfish (<i>Clarias gariepinus</i>) at 2, 5 and 8 h after feeding a starch (SD) or fat (FD) diet. A 2-Way ANOVA (<i>p</i><0.05, Tukey) was used to detect the effects of diet (D), time (T) and the diet*time interaction (D*T) within compartments. Effects are marked with ns for non-significant; # <i>p</i><0.10; * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Means (<i>n</i> = 2) within compartments marked with different letters are significantly different from each other (<i>p</i><0.05).</p

Relative water flux in proximal intestine and stomach [ml g⁻¹ DM].

<p>Relative water flux in the proximal intestine vs. Relative water flux in the stomach of African catfish (<i>Clarias gariepinus</i>) measured at 2, 5 and 8 h after feeding a starch (SD) or fat (FD) diet. The estimated linear models are given in the text. No significant differences were detected between intercepts (<i>p</i> = 0.962) or slopes (<i>p</i> = 0.959) of the linear models (One-Way ANCOVA, <i>n</i> = 2, <i>p</i><0.05).</p

Dry matter

<p>(<b>DM</b>) <b>content of chyme [g kg⁻¹]</b> (<b>Means±SE</b>)<b>.</b> Measured in the stomach (A), proximal intestine (B), mid intestine (C) and distal intestine (D) of African catfish (<i>Clarias gariepinus</i>) at 2, 5 and 8 h after feeding a starch (SD) or fat (FD) diet. A 2-Way ANOVA (<i>p</i><0.05, Tukey) was used to detect the effects of diet (D), time (T) and the diet*time interaction (D*T) within compartments. Effects are marked with ns for non-significant; # <i>p</i><0.10; * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Means (<i>n</i> = 2) within compartments marked with different letters are significantly different from each other (<i>p</i><0.05).</p

Relative water flux [ml g⁻¹ ingested DM]

<p>(<b>Means±SE</b>)<b>.</b> Measured in the stomach (A), proximal intestine (B), mid intestine (C) and distal intestine (D) of African catfish (<i>Clarias gariepinus</i>) at 2, 5 and 8 h after feeding a starch (SD) or fat (FD) diet. A 2-Way ANOVA (<i>p</i><0.05, Tukey) was used to detect the effects of diet (D), time (T) and the diet*time interaction (D*T) within compartments. Effects are marked with ns for non-significant; # <i>p</i><0.10; * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Means (<i>n</i> = 2) within compartments marked with different letters are significantly different from each other (<i>p</i><0.05).</p

Conceptual model of dark calcification impairment by heterotrophy.

<p>Feeding increases metabolic rates, CO₂ production, and as a result proton production in calicoblastic cells. In light, these protons are titrated by photosynthetically generated hydroxide ions in the coelenteron. In darkness, protons accumulate in the calicoblastic ectoderm, increasing the proton gradient between the calicoblastic ectoderm and the calcifying medium (CM). This causes a temporary decrease of the CM pH and aragonite saturation state, shifting the calcification reaction to the left. CC: calicoblastic cell. CM: calcifying medium. M: mitochondrion. CA: carbonic anhydrase. Model based on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052702#pone.0052702-Furla1" target="_blank">[10]</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052702#pone.0052702-AlHorani2" target="_blank">[17]</a>.</p

Voluntary feed intake and growth performance of rainbow trout fed the experimental diets for 6 weeks¹.

<p>DM, dry matter; FI_PCT, Feed intake per percentage body weight; FI_ABS, Absolute feed intake; FI_MBW, Feed intake per metabolic body weight; DGC, Daily growth coefficient; FGR, Feed gain ratio.</p>1<p>Values represent least squares (LS) means (n = 3), row means with different superscript letters were significantly different and assigned only if interaction effect was significant (P<0.05).</p>2<p>H_P/EF - High P/E ratio diet with fat as main non-protein energy source; H_P/EC - High P/E ratio diet with carbohydrate as main non-protein energy source; L_P/EF - Low P/E ratio diet with fat as main non-protein energy source; L_P/EC - Low P/E ratio diet with carbohydrate as main non-protein energy source.</p

Apparent nutrient digestibility coefficient (%; ADC) in rainbow trout fed with four experimental diets¹.

1<p>Values represent least squares (LS) means (n = 3), row means with different superscript letters were significantly different and assigned only if interaction effect was significant (P<0·05).</p>2<p>H_P/EF - High P/E ratio diet with fat as main non-protein energy source; H_P/EC - High P/E ratio diet with carbohydrate as main non-protein energy source; L_P/EF - Low P/E ratio diet with fat as main non-protein energy source; L_P/EC - Low P/E ratio diet with carbohydrate as main non-protein energy source.</p>3<p>ADC of total carbohydrates and energy includes the effect of the added cellulose (indigestible) in diets H_P/EF and L_P/EF.</p

Nitrogen, fat and energy balance in rainbow trout fed the experimental diets for 6 weeks¹.

<p>SEM, Standard error mean; GNI, Gross nitrogen intake; FN, Faecal nitrogen loss; DNI, Digestible nitrogen intake; BUN, Branchial and urinary nitrogen loss; RN, Retained nitrogen; GFI, Gross fat intake; FF, Faecal fat loss; DFI, Digestible fat intake; RF, retained fat; RF/DF, fat efficiency; GEI, Gross energy intake; FE, faecal energy loss; DEI, digestible energy intake; BUE, branchial and urinary energy loss; MEI, metabolisable energy intake; RE, retained energy.</p>1<p>Values represent least squares (LS) means (n = 3), row means with different superscript letters were significantly different and assigned only if interaction effect was significant (P<0·05).</p>2<p>H_P/EF - High P/E ratio diet with fat as main non-protein energy source; H_P/EC - High P/E ratio diet with carbohydrate as main non-protein energy source; L_P/EF - Low P/E ratio diet with fat as main non-protein energy source; L_P/EC - Low P/E ratio diet with carbohydrate as main non-protein energy source.</p

Relation between water temperature (T, °C) and heat production in rainbow trout fed to satiation.

<p>The heat production values (H, kJ kg^−0.8 d⁻¹) are calculated for rainbow trout fed to satiation from literature data <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034743#pone.0034743-Azevedo1" target="_blank">[57]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034743#pone.0034743-Glencross1" target="_blank">[58]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034743#pone.0034743-Glencross2" target="_blank">[59]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034743#pone.0034743-Glencross3" target="_blank">[60]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034743#pone.0034743-Kim1" target="_blank">[61]</a> and from the present study. H was curvilinearly related to temperature, H = 26.6×e^0.0923×T, R² = 0.73.</p