Seasonal differences in ovarian activity in cows

Abstract
The plasma concentrations of LH and prolactin and various parameters of ovarian function were examined in cows on known days of the oestrous cycle during May and June (autumn and winter) and during October (spring). Luteinizing hormone peak frequency and plasma prolactin concentrations were significantly higher in October than during the May–June period (LH, PPPPPPJ. Endocr. (1984) 102, 189–198