Allocation of Matter in the Body of Growing Toads, Bufo bufo : Components of ‘Condition’

The condition, CI = [body mass (g)/length (cm) 3 ]‐1000, tends to increase in toads growing in the laboratory on a diet of meal‐worms. The allocation was therefore studied of ingested food to growth corresponding to maintenance of standard condition (Δ W S ) and to increases in condition, expressing bulky growth. A condition index of 100, typical of toad populations, is chosen to characterize standard growth, higher values expressing bulky growth. The relationship between mass specific standard growth (Δ W s / W 0 ) and actual growth in mass (Δ W / W 0 ) was the same in controls and growth hormone‐treated toads and was independent of sex and season. It could be described by the allometric equation Δ W s / W 0 = 0.28 (Δ W / W 0 ) 1.36 , r = 0.93. The composition of mass representing increases in bulk in excess of a CI = 100 was assessed from allometric relationships established between the indices of the chemical constituents and the overall condition index. The increases in condition were partitioned among the organs and parts of the body from allometric relationships established between indices of organs and body parts and the overall condition index. Treatment with growth hormone enhanced growth in mass and significantly increased the relative proportion of mass allocated to standard growth. However, the effect was not specific to growth hormone, but was an indirect effect of the increased growth rate. Water was the predominant constituent of the growth in bulk, amounting to about 70% of increases in CI. Fat and protein contributed about equally initially, 5–10%, with fat strongly increasing and protein slightly decreasing with increasing condition, fat to approach 20–30% when CI approached 200. Increases in water content largely reflected increases in volume of blood and lymph.