Effect of the sex‐linked dwarf gene on circulating levels of 17/β‐estradiol, progesterone and luteinising hormone in the laying hen

Abstract

1. The sex-linked dwarf gene did not appear to affect the LH, progesterone (P4) and oestradiol 17-beta (E2) levels around the onset of lay in a sample of White Leghorn hens. 2. A longer interval between oviposition and subsequent ovulation was suggested in dwarf layers by a slower decrease in the P4 plasma concentration after the preovulatory peak and is consistent with the increased oviposition interval already described. 3. A higher ratio of E2/P4 basal levels was found in dwarf layers; this is consistent with their lower number of fast-growing follicles and with their reduced laying rate. 4. Lipid mobilisation was modified in dwarf layers (as shown by their reduced abdominal fattiness); although plasma concentrations of triglycerides were normal, unusual correlations between plasma triglycerides, E2 basal concentrations and body weight were recorded.