Initiation of parturition and lactation in the sow: effects of delaying parturition with medroxyprogesterone acetate

Abstract

The synthetic progestagen, medroxyprogesterone acetate (MPA), was administered to sows in late pregnancy with the objective of slightly delaying the time of farrowing and thereby providing more marked associations between hormonal changes and the termination of pregnancy, and the initiation of farrowing and lactation in this species. MPA was administered orally (140 mg, twice daily) to eight sows in late pregnancy on days 112, 113 and 114 of gestation. Parturition was then induced to occur on day 116 by injecting 200 micrograms cloprostenol i.m. on day 115 of gestation. The peripartum changes in the plasma concentrations of progesterone, cortisol, oestradiol-17 beta, relaxin, prolactin, lactose and 13,14-dihydro-15-keto prostaglandin F2 alpha (PGFM) were measured in these sows together with a group of untreated sows. The gestational length for the MPA-treated sows (116.3 +/- 0.3 days, mean +/- S.E.M.) was significantly (P less than 0.01) greater compared with the untreated sows (114.9 +/- 0.3 days). Plasma progesterone declined earlier (P less than 0.05) with respect to the time of parturition in the treated sows compared with the untreated group. With respect to the timing of parturition, the time at which maximal concentrations of relaxin were attained and the timing of the subsequent decline were earlier in the MPA-treated sows. In both groups of sows, the concentration of relaxin increased before the decline in plasma progesterone. In the untreated sows, the concentration of PGFM increased either slightly before or at the same time as the decline in plasma progesterone, whereas in sows treated with MPA, progesterone concentrations began to decline before any significant increase in the plasma concentration of PGFM. The profiles of cortisol, oestradiol-17 beta and PGFM were similar in both groups of sows. In both groups of sows, the timing of the initial increase in the concentration of plasma prolactin coincided with a similar rise in plasma lactose (P less than 0.01). Plasma progesterone either declined earlier or at the same time as the rise in plasma lactose (P less than 0.01) in the treated group of sows only. We conclude that since the prepartum changes in the concentration of progesterone and relaxin occurred before significant changes in the concentration of PGFM in the MPA-treated sows, the nature of the luteolytic factor and the mechanism by which it exerts its action remains obscure. The higher concentration of lactose in the mammary secretion at birth in the MPA-treated sows compared with the untreated group suggested that lactogenesis was initiated earlier with respect to parturition following MPA treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Hormones, IgG and lactose changes around parturition in plasma, and colostrum or saliva of multiparous sows

“…The increase in concentrations of lactose in the colostrum occurred under low P4 plasma concentrations but high E2 and PRL concentrations. This was in agreement with the suggested inhibitory action of P4 [4,47,48] and stimulatory actions of E2 and PRL [34,35,49] on lactose synthesis in the mammary glands. The decrease in the ratio of lactose concentrations in colostrum over those in plasma before and during parturition is in accordance with the passage of lactose from the colostrum to the blood circulation.…”

Variability of colostrum yield and colostrum intake in pigs

“…The negative correlations between lactose, and CP and IgG levels in colostrum confirmed the opposite relationship between the synthesis of lactose and the transfer of immunoglobulins in the mammary gland (Devillers et al, 2004a). Moreover, P4 concentrations were positively correlated with IgG and CP and negatively correlated with lactose content in colostrum, confirming its stimulatory influence on the transfer of IgG from plasma to colostrum in the sow (Jackson et al, 1995) and its inhibitory effect on lactose synthesis (Whitely et al, 1990). Oestradiol-17b was also shown to stimulate the transfer of IgG from plasma to colostrum in cows (Darton and McDowell, 1979) and this could also be the case in sows since a relationship between IgG and E2 concentrations in colostrum was observed.…”

Delaying farrowing using intravaginal devices impregnated with progestagen does not affect the proportion of piglets born alive

“…The dose of MPA infl uenced the number of sows delivering before IVD withdrawal. It was previously shown that orally administered MPA could effectively delay parturition in sows in the presence of corpora lutea (WHITELY et al, 1990). The results have clearly confi rmed that MPA is effective in maintaining gestation in sows even after PGF2α injection and that intravaginal administration of MPA can be used in situations when delaying farrowing is desirable.…”

“…A protocol that combines these two approaches could further concentrate parturitions to week days, thus facilitating farrowing supervision and the cross-fostering of newborn piglets. Previous studies have evaluated oral progestagen treatments to control the farrowing time (KIRKWOOD et al, 1985;GUTHRIE et al, 1987;WHITELY et al, 1990) and prevent early parturition in sows (VANDERHAEGHE et al, 2011). Most of the studies conducted to control reproductive events in sows were based on the oral supplementation of the synthetic progestagen altrenogest (GUTHRIE et al, 1987;WOOD et al, 1992;PATTERSON et al, 2008;VANDERHAEGHE et al, 2011).…”

“…However, other orally-administered synthetic progestagens were also tested. For instance, medroxyprogesterone acetate was orally administrated (twice daily) to sows and shown to effectively delay parturition by one day (WHITELY et al, 1990).…”