horse anterior pituitary extract (Moore & Shelton, 1962a). All recipient ... Averill, R. L. W. & Rowson, L. E. A. (1958) Ovum transfer in the sheep. J. Endocr. 16, 326 ...
SURVIVAL OF FERTILIZED EGGS TRANSFERRED TO EWES AFTER PROGESTERONE TREATMENT J.
N. SHELTON
and
N. W. MOORE
The
McCaughey Memorial Institute, Jerilderie, and Department of Animal Husbandry, University of Sydney, Australia {Received
16th
August 1965)
Summary. Control of the onset of oestrus in ewes by the daily intramuscular injection of progesterone had no effect on the survival of fertilized eggs transferred at the rate of two per ewe to the Fallopian tubes or the uterus. More ewes lambed and more lambs were born following transfer of eight (or more) cell eggs to the uterus than after transfer of eggs of less than eight cells to the Fallopian tubes.
fertility is a common finding following control of the ewe's oestrous with progesterone (Davies & Dun, 1957; Robinson, 1958). Robinson cycle (1961) concluded that progesterone treatment was not detrimental to the fertilizability of eggs shed at the delayed oestrus, whilst Hancock & Hovell (1961) suggested that progesterone treatment prior to oestrus may have an adverse effect upon survival offertilized eggs. A study has been made of the survival of fertilized eggs after transfer to ewes whose oestrous cycles had been controlled by the daily intramuscular injection of 10 mg of progesterone in oil for 16 days. This work forms part of an intensive programme designed to investigate the control of the oestrous cycle in sheep. The test conducted was a simple 2x2 factorial, the factors being the type of cycle of recipient ewes (progesterone controlled or natural) and the site of transfer of eggs (Fallopian tubes or uterus). The latter was confounded with the cell stage of the transferred eggs. Eggs transferred to the uterus were of eight or more cells whereas those transferred to the Fallopian tubes were of less than cells. Two fertilized transferred were to the uterus or the tubes of eggs eight each recipient 2 to 3 days after oestrus. A slight displacement of orthogonality occurred due to insufficiency of eggs available for transfer at the appropriate time so that ninety-three ewes received eggs instead of ninety-six as planned. Fertilized eggs were recovered by the technique of Hunter, Adams & Rowson (1955) from ewes in which multiple ovulation had been induced by the use of horse anterior pituitary extract (Moore & Shelton, 1962a). All recipient ewes were in oestrus within ± 12 hr of their respective donors as determined by twice daily inspections. Eggs were stored until transfer in sheep serum held at 30 to 35° C in dialysis tubes (Averill & Rowson, 1958). 149 Lowered
J. . Shelton and . W. Moore Sixty-one of the ninety-three recipients subsequently lambed producing seventy-nine lambs (Table 1). Progesterone treatment had no effect upon either the number of ewes lambing or the number of lambs born, whereas site of transfer significantly affected both these factors (P
