Seasonal differences in ovarian activity in cows

in Journal of Endocrinology
Authors:
K. P. McNatty
Search for other papers by K. P. McNatty in
Current site
Google Scholar
PubMed
Close
,
N. Hudson
Search for other papers by N. Hudson in
Current site
Google Scholar
PubMed
Close
,
M. Gibb
Search for other papers by M. Gibb in
Current site
Google Scholar
PubMed
Close
,
K. M. Henderson
Search for other papers by K. M. Henderson in
Current site
Google Scholar
PubMed
Close
,
S. Lun
Search for other papers by S. Lun in
Current site
Google Scholar
PubMed
Close
,
D. Heath
Search for other papers by D. Heath in
Current site
Google Scholar
PubMed
Close
, and
G. W. Montgomery
Search for other papers by G. W. Montgomery in
Current site
Google Scholar
PubMed
Close
Restricted access
Rent on DeepDyve

Sign up for journal news

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<0·05; prolactin, P<0·01). The mean diameters of large healthy follicles (≥8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P<0·01 for both follicle types) and each follicle contained more granulosa cells (both P<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<0·05) and secreted more progesterone (P<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.

J. Endocr. (1984) 102, 189–198

 

  • Collapse
  • Expand