Pattern of FSH secretion from birth to 4 months of age in two Moroccan ewebreeds varying in prolificacy

Plasma FSH concentration was monitored weekly for 17 weeks starting at birt h in two Moroccan breeds differing in prolificacy: D'man (rate of ovulation =2.9, n=10) and Timahdite (rate of ovulation=1.1, n=10). Plasma FSH concent rations increased progressively from birth until 17 weeks of age in both br eeds. In ewe lambs, there appear to be genotype differences for FSH at spec ific times during the neonatal period. Mean plasma FSH concentrations were significantly higher in D'man compared to Timahdite ewe lambs at 4-7 and 12 weeks of age (p<0.0001, p<0.0009, p<0.006, p<0.002 and p<0.01, respectivel y). These results demonstrate that the D'man ewe lamb of high prolificacy i s characterized early in life by elevated basal plasma FSH concentrations. (C) 1999 Elsevier Science B.V. All rights reserved.