Allometric changes during growth in rabbits

Abstract

SUMMARYDifferential growth from 1 to 20 weeks of age was studied on 320 rabbits from two lines (New Zealand White and California) and both sexes by means of the allometric equation log y = log a + b log x. Regression lines were fitted to the evolution of organs (blood, skin, thymus, heart–lungs, liver, kidneys and alimentary tract), carcass, tissues (bone, lean and fat) and anatomic components (head, breast and ribs, loin, abdominal wall, fore and hind legs) relative to empty body weight; stomach, caecum and intestines relative to alimentary tract; bone and lean groups relative to total bone and lean and fat depots relative to total fat.The convenience for a correct description of relative growth of determining both the quantitative growth, in order to apply the allometric equation only to the real growth period of each component, and the possible existence of allometric changes, is discussed.The results for each component are presented and discussed. There were no significant differences due to line, and sex had a significant influence (P < 0·001) only on the relative growths of total fat, lean content in the loin and hypodermic fat. All the components, with the exception only of thymus, presented a change in their allometric coefficients. These changes for most components, except fat depots, were concentrated in a small interval of time (4–8 weeks of age) between weaning and the inflexion point of the body weight growth curve.