Influence of supplemental dietary fat on the relative proportions of three classes of lipid in the epiphyseal cartilage of dwarf and non-dwarf chicks.

One hundred and forty-four day-old chicks were allotted to six groups in a 2 x 3 factorial design involving two strains (dwarf, dw and non-dwarf, Dw+) and three levels of supplemental dietary fat (none, moderate and high). The birds were killed at four weeks of age. The overall weight gain and the total lipid content, amount of neutral lipids, glycolipids and phospholipids in the epiphyseal cartilage of the tibia were examined. Supplemental dietary fat resulted in improved weight gain, with the non-dwarfs showing a greater increase. There was no change in total lipid in epiphyseal cartilage with different levels of dietary fat. Increase in dietary fat elicited, in both strains of birds, an increase in the proportion of glycolipids and a concomitant decrease in the proportion of neutral lipids and no change in that of phospholipids. That the stimulatory effect of dietary fat on growth was exerted through an increase in glycolipids at the site of calcification is suggested.