Wool follicle development in the New Zealand Romney and N type sheep. IV. Pre-natal growth and changes in body proportions

Abstract

Growth, and the relative growth gradients over the body, have been studied in N-type and normal Kew Zealand Romney foetuses. Body weights, and a series of linear measurements taken between different points over the body, have been obtained from a series of foetuses of known ages. Huxley's allometric growth ratios have been calculated from these measurements by using the least squares regression. There are no significant gromth differences between foetuses belonging to the different AT-genotypes of the New Zealand Ronmey. Foetuses belonging to the New Zealand Romney and some British breeds grow at a faster rate than South African Merino foetuses studied by Malan and Curson (1936a) and Cloete (1939). Relative growth gradients over the body are, in general, similar to those of other mammals, but the results do not support the theory of Cloete (1939), that the relative growth rate of a part of the body is solely a function of the age of the part.