Response of sows to oestradiol benzoate treatment after weaning at two stages of lactation

Edwards, S.; Foxcroft, G. R.

doi:10.1530/jrf.0.0670173

Cited by 15 publications

(13 citation statements)

References 14 publications

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“…Finally, in lactating sows, the hormones and neurotransmitters associated with suckling could block the discharge of GnRH and that of LH in response to high levels of oestrogens. In weaned sows, the duration of lactation influences the responsiveness to OB; the amplitude of the oestrogen-induced LH surge is higher after 35 than after 21 or 10 d of lactation (Edwards and Foxcroft, 1983b;Kirkwood et al, 1984b).…”

Section: Ovarian Activitymentioning

confidence: 99%

Endocrine bases of lactational anoestrus in the sow

Quesnel¹,

Prunier²

1995

Reprod. Nutr. Dev.

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Summary ― Parturition in the sow is followed by a period of anovulation which is prolonged by lactation. Follicular development and luteinizing hormone (LH) secretion are depressed during the last month of pregnancy. After parturition, LH secretion increases but is again inhibited by the establishment of lactation. Lactating sows are submitted to stimuli originating from the young, whose intensity culminates 3-14 d post-partum (pp), and to high nutrient requirements for milk production. The

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Section: Ovarian Activitymentioning

confidence: 99%

Endocrine bases of lactational anoestrus in the sow

Quesnel¹,

Prunier²

1995

Reprod. Nutr. Dev.

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“…Concentrations of LH are maximally suppressed by nursing of piglets and increase following weaning, but not after ovariectomy during lactation (6,10,11,18,19).…”

Section: Discussionmentioning

confidence: 99%

Influence of follicular ablation during lactation on postweaning interval to estrus, ovulation rate, and endocrine function in sows

Cox

Armstrong

Britt

1987

Domestic Animal Endocrinology

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Duroc sows farrowed second litters in March and lactated 35 ± 2 days. At 36 hr before weaning, electrocautery of follicles 2: 3 mm in diameter (n=8) or sham surgery (n=5) was performed to test the hypothesis that ablation of medium-sized follicles would prolong the duration of postweaning anestrus. Number of follicles and diameters at surgery were: 1.3 ± .6 (> 5 mm diameter), 26 ± 1 (3 to 5 mm) and> 20 « 3 mm). Blood samples were collected at 15 min intervals for 3 hr beginning at -12, 0, 12,60 and 96 hr from weaning. Interval to estrus was 3.4 ± .2 days in seven of eight cauterized sows and 3.6 ± .6 days for sham-surgery sows. The remaining cauterized sow was anestrus at slaughter, 40 days after weaning. Number of corpora lutea and pregnancy rate were 15.8 ± .6 and 92%, respectively, and were similar between sham surgery and cauterized sows. Concentration of follicle stimulating hormone (FSH) at 12 hr before weaning was greater in sows subjected to electrocautery than for sham surgery sows, but FSH values were similar at other sampling times. Concentrations of estradiol were similar at all times for both treatment groups. Luteinizing hormone (LH) was higher (P<.05) at 60 hr in cauterized sows because of the onset of the preovulatory LH surge in one sow. We conclude that destruction of medium-sized ovarian follicles before weaning did not influence postweaning reproductive performance.

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“…While consideration of the LH response data indicated that higher oestradiol benzoate doses may be required, particularly after short lactations, Hausler et al (1980) concluded that low pregnancy rates after treatment with PMSG-hCG at 5 or 10 days post partum were due to decreased ovarian responsiveness and/or an unfavourable uterine environment. Also, prolonged high plasma levels of oestrogen have been shown to prevent the periovulatory rise in plasma FSH concentrations (Edwards & Foxcroft, 1983) and high post-mating oestrogen concentrations may adversely affect tubai egg transport, with consequently increased embryo mortality (Varley, Atkinson & Ross, 1981). Such factors may have contributed to the reduction in pregnancy rates of sows in Group S-E2 compared with that of sows in Group S-C in Exp.…”

Section: Discussionmentioning

confidence: 99%

“…Further, short lactations have been shown to be associated with reduced gonadotrophin secretion at the first post-weaning oestrus (Edwards & Foxcroft, 1983 ;Kirkwood et al, 1984). The reasons for this reduction of gonadotrophin secretion and its physiological consequences are not known.…”

Section: Introductionmentioning

confidence: 99%

“…It has been suggested that the hypothalamus of the sow may be less responsive to oestrogen stimulation at the post-weaning oestrus after short lactations (Kirkwood et al, 1984). However, previous studies using oestrogen to control sow reproduction used high dose levels, with consequent non-physiological plasma oestrogen profiles (Elsaesser & Parvizi, 1980;Edwards & Foxcroft, 1983). This study was undertaken to determine a minimum effective dose of oestradiol benzoate for induction of oestrus and thereafter to ascertain the influence of this dose on plasma LH and prolactin concentrations in sows after very short lactations.…”

Section: Introductionmentioning

confidence: 99%

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Effects of oestradiol benzoate treatment on the reproductive performance and endocrine status of sows after lactations of 10 or 35 days

Kirkwood¹,

Lapwood²,

Smith³

et al. 1984

Reproduction

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Forty-two Landrace X Large White sows were used in 3 studies of oestradiol benzoate treatment 24 h (E1) or 48 h (E2) after piglet removal, following lactations of 10 (S) or 35 (L) days, or were untreated controls (C). For Exp. 1, oestradiol benzoate doses were 4, 16 and 64 micrograms/kg body weight; since highest mean LH peaks followed use of the 16 micrograms/kg dose, this treatment was used in later studies. Treatments for Exp. 2 were S-E1 and L-E1 (N = 3). Pregnancy rates were 1/3 and 2/3, respectively, while 10-day weaned sows tended to have longer weaning-remating intervals, shorter oestrous periods and lower post-injection oestradiol peaks. Post-treatment LH peaks were recorded from all L-E1 sows, but only one S-E1 animal. Treatments S-E2, L-E2, S-C and L-C (N = 6) were used in Exp. 3; pregnancy rates were 1/6, 6/6, 5/6 and 6/6, respectively, while peak oestradiol levels were 49.5 +/- 8.3, 74.8 +/- 15.1, 21.7 +/- 2.0 and 51.8 +/- 26.5 pg/ml, respectively. Weaning-remating intervals were extended in S-C sows (P less than 0.05), while oestradiol treatment prolonged behavioural oestrus. LH peak values were reduced after short lactations, but not affected by oestradiol treatment. Plasma prolactin concentrations at weaning were higher in sows in treatment S than in treatment L, while at the subsequent oestrus in oestradiol-treated sows they were elevated more and for longer periods than in controls. These results demonstrate that reduced gonadotrophin secretion and fertility after short lactations are not overcome by treatment with oestradiol benzoate.

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Response of sows to oestradiol benzoate treatment after weaning at two stages of lactation

Abstract: Summary. The

Cited by 15 publications

References 14 publications

Endocrine bases of lactational anoestrus in the sow

Endocrine bases of lactational anoestrus in the sow

Influence of follicular ablation during lactation on postweaning interval to estrus, ovulation rate, and endocrine function in sows

Effects of oestradiol benzoate treatment on the reproductive performance and endocrine status of sows after lactations of 10 or 35 days

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