“…The larger the dose of hormone administered the greater is the ovarian response and the greater is the variability in response (Folley & Malpress, 1944;Gordon, Williams & Edwards, 1962;Lamond, 1970; Mauléon, Mariana, Benoît, Solari & Chupín, 1970;McGaugh & Olds, 1971;Gordon, 1975). Many authors have reported wide individual variations in ovarian response both in heifers and lactating cows when injected with a standard dose of PMSG (Rowson, 1951;Gordon et al, 1962;Hafez, Sugie & Hunt, 1963;Scanlon, Sreenan & Gordon, 1968;Gordon, 1975;Newcomb, 1976). Many authors, including Baker (1973) and Polge & Rowson (1973), have suggested that at least part of this variability in response may be caused by variation between batches of PMSG in their ability to induce superovulation.…”