Influence of Plane of Nutrition on Body Composition, Organ Size and ...

ENERGY UTILIZATION DURING REALIMENTATION 2531MetabolizableTABLE 5(ME) intakes, live weight gain and gain <strong>of</strong> empty body components<strong>of</strong> male and female rats during period 2weightbodySexMaleFemaleMaleMaleFemaleFern intakekcal/d55.141.838.942.941.743.424.827.730.728.129.931.614.717.816.119.51.58Livegaing/d4.641.941.754.871.643.47-1.191.864.800.031.484.55-1.861.79-1.251.860.51Emptyweightg/d4.362.581.994.432.413.66-0.761.704.341.262.044.39-1.611.70-0.451.980.41Watergaing/d2.471.151.022.540.921.71-0.521.052.780.500.852.60-1.131.12-0.691.1gaing/d0.670.230.290.800.240.56-0.310.130.62-0.190.160.63-0.270gaing/d1.020.390.560.870.430.680.000.380.870.210.380EnergyaleMaleMaleMaleFemaleFernaleFemaleMaleMaleFemaleFemaleRSDTreatment1HHHHHMMHHMMHHLMMLHHLMMLHMLLMMLLMME'Treatments are designated by a two-letter code. The first letter indicates that the target gain during the initial21-d period was 105 (H), 40 (M) or —25 (L) g. The second letter indicates that the target gain during the second21-d period was 105 (H), 40 (M) or -25 (L) g.(HH>MH = LH). Percentages <strong>of</strong> emptybody weight gain as protein were 23.4, 19.6and 20.0 for HH, MH and LH male rats,respectively. This pattern was also evidentfor male rats assigned to the M treatmentduring period 2. Percentages <strong>of</strong> empty bodyweight gain as protein were 28.1, 22.4 and21.2 for HM, MM and LM male rats. Theseresults suggest that protein gain duringperiod 2 was influenced by protein mass atthe beginning <strong>of</strong> the period. Similar patterns were not observed when similar comparisons were made with female ratsassigned to the H or M treatments duringperiod 2. No consistent patterns were apparent in males or females for the proportion <strong>of</strong> fat in live weight gain with respectto previous nutritional treatment.This experiment was designed in such away that there were three groups <strong>of</strong> ratswith the same age but different bodyweights at the beginning <strong>of</strong> period 2 resulting from different levels <strong>of</strong> food intake during period 1. The effect <strong>of</strong> previousnutritional treatment on the efficiency <strong>of</strong>utilization <strong>of</strong> ME for maintenance or gainwas evaluated by combining treatments according to the level <strong>of</strong> nutrition duringperiod 1 (HH + HM + HL; MH + MM + ML;LH + LM). No evidence <strong>of</strong> significant sex effects was observed in the initial analyses;thus male and female rats were both includedin the final regression analyses (table 6). Efficiencies <strong>of</strong> utilization <strong>of</strong> ME for gain (b2)were lower (P < 0.05) for rats <strong>of</strong> the Htreatment during period 1 than for those <strong>of</strong>the M or L treatment. Although not statistically compared, maintenance (bilb2) appeared to decrease substantially as previouslevel <strong>of</strong> nutrition decreased. Estimates <strong>of</strong>the metabolizable energy required for energy equilibrium <strong>of</strong> rats from the H, M and Lprevious treatment groups were 114, 107and 86 kcal/(kg°7s-d), respectively.Weights <strong>of</strong> internal organs obtained atthe end <strong>of</strong> period 2 are shown in table 7. Itis not surprising that organ weights wererelated to body weight. However, whenDownloaded from jn.nutrition.org by guest on August 9, 2014