Relationships between prolactin, LH and broody behaviour in bantam hens

Abstract

The interactions between broody behaviour and changes in concentrations of plasma prolactin and LH were investigated in bantam hens. Adoption of newly hatched chicks caused incubating hens to leave their nests and prevented plasma prolactin decreasing as rapidly as in hens deprived of their nests and not given chicks. Further, the hens allowed to rear chicks came back into lay later (P less than 0.001) than the hens not allowed chicks. Plasma prolactin decreased and plasma LH increased in hens deprived of their nests: these changes were reversed when the hens re-nested. The changes in plasma LH and prolactin in nest-deprived and re-nesting birds were not always synchronous; this was particularly clear immediately after nest deprivation when the increase in plasma LH preceded the decrease in the plasma prolactin. Readiness to incubate disappeared between 48 and 72 h after nest deprivation and corresponded with the time when plasma prolactin decreased to baseline values. Administration of ovine prolactin depressed (P less than 0.01) the initial increase in plasma LH after nest deprivation, but repeated administration of prolactin for up to 72 h failed to suppress plasma LH to the values found in incubating hens. Repeated administration of ovine prolactin at 5- to 8-h intervals for 72 h maintained readiness to incubate in nest-deprived hens. It is concluded that the secretion of prolactin in broody hens is facilitated by the presence of chicks and that increased concentrations of plasma prolactin maintain incubation behaviour. In incubating hens the secretion of LH and prolactin may be partly regulated independently. In addition, LH secretion may also be inhibited by increased plasma prolactin.

Uncoupling clutch size, prolactin, and luteinizing hormone using experimental egg removal

“…14 The latter finding is inconsistent with a direct role for PRL in clutch size determination. 15 We also found no evidence that individual variation in the magnitude and direction of 16 changes in LH were associated with changes in PRL, as would be predicted by a systemic 17 inhibitory effect of PRL on LH. Other studies have also not found evidence for inhibitory we would expect if these traits were mechanistically linked.…”

Effect of anti-prolactin drug and peppermint on broodiness, laying performance and egg quality in indigenous hens

“…Still it is not fully elucidated that a change in the concentration of prolactin is responsible for timing of oviposition in domestic hen (Wentworth et al, 1983) or due to longer intervals of LH surges. Also prolactic plays a role in the development of broodiness in poultry with reference to turkey and bantam hens (Sharp et al, 1988) nothing is reported in this breed. The plant family Lamiaceae has received the greatest interest in poultry feed, with peppermint, thyme and oregano as the most popular representatives (Burt, 2004).…”

“…Broodiness basically means a hen sits on her eggs for the purpose of hatching the embryos. Physiologically, it has been well established that prolactin (PRL) plays an important role in the onset of incubation of hens (Sharp et al, 1988;March et al, 1994;Ohkubo et al, 1998). Increased plasma PRL concentration is associated with the occurrence of broodiness (Burke and Dennison, 1980;Bacon, 1983).…”

The Role of Prolactin in the Regulation of Clutch Size and Onset of Incubation Behavior in the American Kestrel

“…Cessation of egg laying is associated with increased concentrations of plasma prolactin (Etches, Garbutt, and Middleton, 1979;Burke and Dennison, 1980;Lea et al, 1981;Bluhm, Phillips, and Burke, 1983;Hall and Goldsmith, 1983;Silverin and Goldsmith, 1983), and in turkeys and domestic fowl (Sharp, Macnamee, Sterling, Lea, and Pedersen, 1988), administration of exogenous prolactin suppresses plasma gonadotropins necessary for egg production. However, there is additional evidence that the suppression of gonadotropin secretion in incubating birds also involves a mechanism independent of increased prolactin secretion (Sharp et al, 1988;Lea and Sharp, 1989;Sharp, Sterling, Talbot, and Huskisson, 1989;Lea, Richard-Yris, and Sharp, 1996).…”