Seasonal variations in prolactin, growth hormone and thyroid hormones and the prolactin surge at ovulation do not affect litter size of ewes during pregnancy in the oestrous or the anoestrous season

The purpose of this study was to investigate the effect of suppressing the periovulatory prolactin peak on the fertilization rate and the litter size of the ewe. At the same time a comparison was made between the changes in prolactin, GH, progesterone, TSH and thyroid hormone concentrations in gestation in the oestrous and the anoestrous seasons.