Progesterone and Oestrogen and the Initiation of Lactation in Ewes

Hartmann, Peter; Trevethan, P.; Shelton, J. N.

doi:10.1677/joe.0.0590249

Cited by 74 publications

(36 citation statements)

References 19 publications

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“…It took the under-fed ewes nearly 15 days longer to fall below this level than wellfed ewes. Furthermore, by the day before lambing, in neither group, had progesterone levels fallen below the second threshold of 1 ng.mL −1 which is considered by Hartmann et al [33] to be necessary for copious synthesis of colostrum. On the day before lambing, plasma concentrations of progesterone were still too high in 60% of the ewes in each group.…”

Section: Discussionmentioning

confidence: 70%

Endocrine and metabolic factors involved in the effect of nutrition on the production of colostrum in female sheep

Banchero

Clariget²,

Bencini

et al. 2006

Reprod. Nutr. Dev.

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-We investigated the physiological relationship between diet during pregnancy and colostrum production in ewes to test the hypothesis that for ewes that are in low body condition, with low fat reserves, the food supply will be the main source of energy for colostrum synthesis. To this end, we measured the amount of colostrum accumulated by ewes under two levels of nutrition. We also measured the circulating concentrations of metabolites and hormones associated with lactogenesis (β-hydroxybutyrate, glucose, progesterone, prolactin, cortisol, growth hormone, leptin, insulin and insulin-like growth factor-I) Ewes were either under-fed at 70 (n = 15) or well-fed at 110% (n = 10) of their daily metabolisable energy requirement during the last two months of pregnancy. Colostrum accumulation up to parturition was 168 ± 48 g for under-fed ewes and 451 ± 103 g for well-fed ewes. After birth, under-fed ewes produced less colostrum than well-fed ewes but the difference was no longer significant. The level of nutrition also influenced the plasma concentrations of hormones and metabolites related to lactogenesis. Progesterone concentrations decreased before lambing in all animals but in under-fed ewes the fall appeared to be too small to initiate the onset of colostrum production. β-hydroxybutyrate concentrations were higher in under-fed than in well-fed ewes, suggesting that the under-fed ewes were mobilising more adipose tissue but they still did not meet their ME requirements for colostrum production. We concluded that, in underfed ewes, there are insufficient nutrients for adequate lactation and the hormone regime is inappropriate for good udder development and colostrum synthesis. udder development / lactogenesis / β-hydroxybutyrate / glucose / progesterone / prolactin / cortisol / growth hormone / leptin / insulin / insulin-like growth factor-I / lamb mortality

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Section: Discussionmentioning

confidence: 70%

Endocrine and metabolic factors involved in the effect of nutrition on the production of colostrum in female sheep

Banchero

Clariget²,

Bencini

et al. 2006

Reprod. Nutr. Dev.

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“…Progesterone was ineffective in suppressing the concentration of lactose in milk during established lactation. Similarly, Hartmann et al (1973) have shown that ewes receiving progesterone immediately after Caesarean section had a significantly decreased milk yield and lactose concentration whereas the administration of progesterone to ewes with established lactation did not lead to any significant change in either milk yield or concentration of lactose in the milk. In this connection Shyamala (1979, 1980) recently reported the absence of specific receptors for progesterone in mammary tissue from mice in mid-lactation.…”

Section: Discussionmentioning

confidence: 89%

Progesterone Control of the Initiation of Lactose Synthesis in the Rat

Nicholas¹,

Hartmann²

1981

Aust. Jnl. Of Bio. Sci.

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The in vitro incorporation of ['4C]glucose into lactose in mammary tissue, the concentration of lactose in the mammary tissue and the concentration of lactose in the mammary secretion were determined during late pregnancy and lactation in the rat. These changes were related to the decline in blood progesterone during late pregnancy. The incorporation of [,4C]glucose into lactose was detected on day 20 of pregnancy; it increased gradually until day 22 and then increased rapidly just prior to term (day 23 of pregnancy) to reach mean ± s.e.m. maximum hourly values of 12·0 ± 1· 5 cpm x 10 4 1 g by day 3 of lactation, and then declined to lower values (6· 1 ± 0·6 cpm x 10 4 /g) by day 20 of lactation. The concentration of lactose both in the mammary tissue and in the mammary secretion increased rapidly over the last 24 h of pregnancy and then more gradually after birth to reach mean ± s.e.m. maximum values of 6·85 ± 1 ·11 mg/g tissue and 43·1 ± 2·1 gil respectively on day 15 of lactation. The decline in plasma progesterone to low levels between days 21 and 22 of pregnancy preceded the rapid increase in the concentration of lactose in the mammary tissue. A similar relationship was observed between the decline in progesterone and the increase in lactose in mammary tissue in rats Caesarean-sectioned on day 19 of pregnancy, and the administration of progesterone immediately following Caesarean section significantly depressed the accumulation of lactose in the mammary tissue. The results support the involvement of progesterone withdrawal in lactogenesis in the rat and indicate that ['4C]glucose incorporation into lactose and the concentration of lactose both in the mammary tissue and in mammary secretion are useful indicators of the synthetic activity of the mammary gland.

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“…Although this effect was observed in animals which-underwent Caesarean section, it did not appear to be caused by surgical delivery of the kids; lactational yields were also low in the one intact MPA-treated animal which delivered spontaneously. This effect was not unexpected; MPA used as a long-term contraceptive interferes with lactation in some women (Parveen, Chowdhury & Chowdhury, 1977), and a reduction in circulating progesterone concentration is an important factor controlling lactogenesis in goats (Davis et al, 1979) and sheep (Hartmann, Trevethan & Shelton, 1973). The MPA preparations used in the present study (Depo-Provera & Promone-E) are long-acting, microcrystalline formulations released over a long period in primates (Cornette et al, 1971;Kirton & Cornette, 1974;Shrimanker, Saxena & Fotherby, 1978), and MPA was found in the circulation of the goats 1-2 months after the end of treatment.…”

Section: Discussionmentioning

confidence: 96%