Quantitative relationships between suckling-induced teat stimulation and the release of prolactin, gastrin, somatostatin, insulin, glucagon and vasoactive intestinal polypeptide in sows

Abstract

The pituitary hormones prolactin and oxytocin play important roles in the production and ejection of milk. In addition, some gastrointestinal peptides are released in response to suckling. During suckling, the piglets massage the udder of the sow both before and after let-down and the duration of suckling is correlated to the amount of milk produced by the sow. The aim of this study was to investigate whether there is a quantitative relation between the release of prolactin, gastrin, somatostatin, insulin, glucagon and vasoactive intestinal polypeptide (VIP) and the amount of stimulation of the sow's teats by the piglets. Repeated blood samples were drawn from three Swedish Landrace sows during three consecutive nursings by each sow on days 1, 3, 7 and 14 after parturition. The duration of massage by the piglets was noted, as was the number of piglets massaging. Hormone levels were quantified by radioimmunoassay. The release of prolactin, somatostatin, insulin, glucagon and VIP but not of gastrin were found to be significantly related to the amount of teat massage performed by the piglets during the first 2 weeks of lactation. The release was related to the duration of piglet massage or to the combined effect of duration and the number of piglets massaging but not to the number of piglets massaging per se. The basal level of prolactin was found to decrease during this time.

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

“…The decrease in P4 and the increase in E2 are necessary for lactogenesis to occur in response to the high levels of PRL [3,[33][34][35]. Despite a decrease following parturition, our data confirm that plasma PRL concentrations remain relatively high thereafter, which is likely due to stimulation by the suckling piglets [36,37]. The existence of a negative correlation between P4 and E2 and, between P4 and PRL, together with the coincidental fall of P4 on the one hand and rises in E2 and PRL on the other hand, support the proposed role of the P4 decrease as the trigger for other hormonal variations at parturition [3,4,35,38].…”

Alternative farrowing systems: design criteria for farrowing systems based on the biological needs of sows and piglets

“…During farrowing an increase in plasma oxytocin concentrations, promoting uterine contraction for piglet expulsion (Castré n et al, 1993b), also results in continuous let-down of colostrum from the teats. Feedback from the udder, stimulated by massage from piglets, also increases oxytocin concentration and milk let-down (Algers et al, 1991). Colostrum availability declines exponentially during the first 24 h of secretion, before changing to milk by 30 h post partum (Le Dividich et al, 2005).…”

“…Tactile stimulation performed by the piglets at the udder fulfils several functions; suckling massage releases prolactin that assists with adapting maternal physiology to cope with lactation (Algers et al, 1991) and, dependent on the time spent massaging, increases the teat milk yield for the next suckling -the 'restaurant hypothesis' (Gill and Thomson, 1956;Algers and Jensen, 1985). Nose-to-nose contact between piglet and sow post let-down is thought to signal need and reaffirm bonds and recognition.…”

Endocrine bases of lactational anoestrus in the sow

“…During lactation, suckling by piglets elicits an increase in prolactin (Kendall et al, 1983;Mattioli et al, 1988;Algers et al, 1991 ). This effect of suckling is mediated, at least in part, through an opioid-dependent mechanism (Mattioli et al, 1986;Barb ef al, 1987;Armstrong etal, 1988a (Armstrong et al, 1990;Rushen et al, 1993).…”