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Different scenarios for calculation of the feed conversion ratio (FCR)

 Scenario Feed > 0 Feed = 0 ΔBiomass > 0 FCR > 0 FCR = (+)0 ΔBiomass = 0 FCR = x/0 = ∞ FCR = 0/0 ΔBiomass < 0 FCR < 0 FCR = (−)0

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Equations proposed for calculation of the feed conversion ratio (FCR) and the FCR index (iFCR)

 ΔBiomass Feed FCR Formulas for FCR1 Formulas for iFCR >0 >0 >0 0 = (+)0 0.1 = 0 >0 = x/0 EMFR×97+9 = 0 = 0/0 9 <0 > 0 <0 = 0 = (−)0
1EMFR = estimated monthly feeding rate.

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Exclusion rules for registers to calculate the production and management index (PMI)

 Criteria1 Cause of exclusion Excluded ADGr < 0 Loss of weight 52 ADGr ≥ 0.5 Growth rate too high 2 EMM ≥ 0.30 Excessive estimated mortality 41 EMM ≥ 0.20, period ≤ 7 d Excessive estimated mortality in a nonrepresentative period of time 16 FCR > 50 FCR too high 14 0.1 > FCR > 0 FCR too low 18 ΔBiomass = 0, feed = 0, period ≤ 15 d Noncalculable FCR and period too short 165 EMFR > 3 EMFR too high (equivalent to a daily feeding rate greater than 10% of biomass) 0 Density > 500 fish/m3, biomass > 200 kg/m3 Fish density too high 8 Density < 50 fish/m3, biomass < 10 kg/m3 Fish density too low 9 Density < 100 fish/m3, biomass < 1 kg/m3 Fish density too low 10 Fish movements Changes in population size 98
1ADGr = relative average daily growth; EMM = estimated monthly mortality; FCR = feed conversion ratio; EMFR = estimated monthly feeding rate.

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Weight (g) stratified by tilapia variety

 Variety n % Mean1 SD Median Minimum CI95% Maximum Black 4,476 52.0% 426.9a 315.1 365.0 2 11.0 1,085.0 1,590 Red 3,881 45.1% 156.8c 136.6 130.0 2 4.0 453.0 1,100 Spotted 143 1.7% 305.9b 259.0 271.0 2 3.0 903.4 1,035 Mixed 114 1.3% 280.5b 124.7 274.0 6 55.9 544.0 850 Total 8,614 100% 301.3 280.9 220.0 2 6.0 1000.0 1590
a–cDifferent superindexes in the same column show significant differences comparing pairs of results with the Mann-Whitney U test.
1Significance of the Kruskal-Wallis test, P < 0.001.

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PMI stratified by tilapia varieties

 Variety n Mean1 SD Median Minimum 95% CI Maximum Black 4,288 1.0248 0.3759 1.0243 0.2672 0.3693 1.8266 2.832 Red 3,660 1.1661 0.3493 1.1437 0.2633 0.4028 2.0158 3.550 Total 7,948 1.0898 0.3706 1.0894 0.2633 0.3758 1.9144 3.550
1Significance of Mann-Whitney U test, P < 0.001.

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Production and management index stratified by tilapia varieties and weight categories

 Black tilapia Red tilapia Item n Mean SD Median n Mean SD Median P-value Weight ≤20 g 136 1.1385b 0.5853 1.0292 448 1.0894c 0.4999 1.1662 0.360 20–49 g 202 1.2495a 0.3360 1.2374 484 1.3509a 0.3401 1.3028 0.001 50–119 g 416 1.1262b 0.3708 1.0846 750 1.2476a,b,c 0.2641 1.2018 <0.001 120–299 g 1,054 1.0373c,d 0.3264 1.0305 1,453 1.1175c 0.3014 1.0826 <0.001 300–599 g 1,163 0.9848d,e 0.3430 0.9802 498 1.0739c 0.3437 1.0570 <0.001 600–999 g 1,103 0.9549e 0.3897 0.9710 22 1.1418b,c 0.2988 1.0783 0.021 ≥1,000 g 214 1.0591c 0.4318 1.1176 5 1.3124a,b 0.7224 1.2809 0.376 Total 4,288 1.0248 0.3759 1.0243 3,660 1.1661 0.3493 1.1437 <0.0011 P-value <0.0012 <0.0012
a–eSuperindexes in the same column show significant differences comparing pairs of results with the Mann-Whitney U test.
1Significance of the Mann-Whitney U test.
2Significance of the Kruskal-Wallis test.

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Production and management index stratified by season (using only black and red tilapias)

 Variety n Mean1 SD Median Minimum CI95% Maximum Rainy 5,455 1.0847 0.3787 1.0856 0.2633 0.3732 1.9216 3.5495 Dry 2,493 1.1011 0.3522 1.0944 0.2846 0.3815 1.8854 2.7735 Total 7,948 1.0898 0.3706 1.0894 0.2633 0.3758 1.9144 3.5500
1Significance of Mann-Whitney U test, P = 0.026.