Effect of level of food intake of ewes on the secretion of LH and FSH and on the pituitary response to gonadotrophin-releasing hormone in ovariectomized ewes.
The effect of level of food intake on LH and FSH profiles and pituitary sensitivity to gonadotrophin-releasing hormone (GnRH) was investigated in two groups of 12 ovariectomized ewes. Ewes with a high intake (group H) had a mean daily intake (+/- S.E.M.) of 1.99 +/- 0.075 kg dry matter (DM)/head per day while ewes with a moderate intake (group M) consumed a mean of 1.02 +/- 0.021 kg DM/head per day. Ovaries were surgically removed from six ewes of each group on day 11 of the luteal phase and from the remainder 30 h after an injection of 100 micrograms prostaglandin analogue given on day 11 to induce luteolysis. During both the luteal phase and the follicular phase, mean LH and FSH concentrations and LH pulse frequencies and amplitudes were unaffected by the level of intake but mean plasma prolactin concentrations were higher (P less than 0.05) in group H than in group M ewes in the follicular phase. Mean LH and FSH concentrations at day 2 after ovariectomy were unaffected by treatment while mean prolactin concentrations were higher (P less than 0.05) in group H than in group M ewes. At day 7 after ovariectomy, mean LH and FSH concentrations were lower (P less than 0.05) in group H than in group M ewes although mean LH pulse frequencies and pulse amplitudes were not significantly affected by the level of intake at either time.(ABSTRACT TRUNCATED AT 250 WORDS)
Rhind
S M
SM
Macaulay Land Use Research Institute, Bush Estate, Penicuik, Midlothian.
Martin
G B
GB
McMillen
S
S
Tsonis
C G
CG
McNeilly
A S
AS
D000818:Animals; D004435:Eating; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D010052:Ovariectomy; D010060:Ovulation; D010902:Pituitary Gland / Q000187:drug effects; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D010906:Pituitary Hormone-Releasing Hormones; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone