Comparative lambing dates of untreated ewes and ewes treated with various hormone preparations.

Abstract

Approximately 1000 commercial ewes of different ages and types, and 400 purebred ewes of three different breeds, were included in the study. Three hormone preparations available on the market and similar to others being offered for sale were used. One of these was a gonadotropic hormone prepared from dried sheep pituitaries; another was a synthetic estrogenic (or heat producing) hormone known as Stilbesterol; and the third product used was a naturally occurring estrogenic material obtained from pregnancy urine. Different groups of ewes in each flock were given these preparations during the early part of June, 1951, and their subsequent breeding and lambing dates compared with groups within each flock that were untreated. The accompanying table gives the results of the study on the commercial ewes.