PMID: 6540288Aug 1, 1984Paper

Seasonal differences in ovarian activity in cows

The Journal of Endocrinology
K P McNattyG W Montgomery

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, P less than 0.05; prolactin, P less than 0.01). The mean diameters of large healthy follicles (greater than or equal to 8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P less than 0.01 for both follicle types) and each follicle contained more granulosa cells (both P less than 0.01) in May-June than in October. The LH responsiveness of theca interna with respect to androstenedione production and the levels of aromatase activity in granulosa cells did not differ with time of year. The corpora lutea were heavier (P less than 0.05) and secreted more progesterone (P less than 0.01) in May-June than in October. It is concluded that seasonal differences in ovarian activity exist in cows and that these differences are probably the consequence of seasonal differences in gonadotrophin secretion.

Citations

Dec 1, 1987·International Journal of Biometeorology·M C PieterseW J Koops
Jun 24, 2003·Animal Reproduction Science·G A BóM F Martínez
May 1, 1997·Animal Reproduction Science·D WolfensonR Meidan
Jul 1, 1991·Zentralblatt für Veterinärmedizin. Reihe A·P V MiettinenJ J Setälä
Apr 18, 2014·Animal : an International Journal of Animal Bioscience·T R CarthyD Ryan
Jun 1, 1996·The Veterinary Quarterly·G OpsomerA de Kruif
Feb 15, 2011·Animal Reproduction Science·Leon J SpicerJuan A Grado-Ahuir
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Jan 25, 2003·Journal of Animal Science·F J WhiteG L Morgan

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