Abstract
The study provides baseline data regarding 17--estradiol (E), progesterone (P), and cortisol profile of 30 Nicastrese goats during different physiological periods. Animals were evaluated monthly from the pre-mating period (non-pregnant), during pregnancy, and from 30 to 105 d of lactation. The effects of single or twin births and the kid's sex were also considered. Serum E, P, and cortisol concentrations were measured using immunoenzymatic assay kits. The highest concentrations of E and P () were found during pregnancy and their lowest values () in the non-pregnant period. E was negatively correlated with P (; ) during lactation. The mothers with twin kids showed the highest concentration of P () at 95–115 d of gestation and the lowest of E () at 50–70 d of lactation. Pregnant goats carrying male kid(s) presented the highest E concentrations () at 130–150 d of gestation. Different physiological conditions induced a temporal relationship with the endocrine profile in Nicastrese goats. Understanding the effects of single or twin fetuses on the gestation and lactation will also be helpful to improve the managemental approach for the health of mothers and their kids.
Highlights
Physiological gestation and lactation periods, especially the transition phase, are characterized by several metabolic and neuroendocrine changes intending to dynamically guarantee the growth of fetus and mammary glands (Iriadam, 2007; Krajnicáková et al, 2004; Skotnicka, 2003)
The corpus luteum is the only source of P4 for the physiological maintenance of pregnancy in goats and an increased number of corpora lutea may induce a greater P4 and E2 secretion, leading to the stimulation of mammary gland growth in goats carrying twin fetuses (Khan and Ludri, 2002b)
We evaluated the Nicastrese goat, a local breed reared in the Calabria region, a southern Italian region in which about 4800 individuals can be found, reared in 77 flocks
Summary
Physiological gestation and lactation periods, especially the transition phase, are characterized by several metabolic and neuroendocrine changes intending to dynamically guarantee the growth of fetus and mammary glands (Iriadam, 2007; Krajnicáková et al, 2004; Skotnicka, 2003). The interaction between the maternal–fetal unit implies an expression of greater metabolic stress in the mother with the advance of pregnancy approaching parturition, represented by high cortisol concentrations at parturition to an increased fetal adrenal responsiveness to adrenocorticotropic stimuli (Ford et al, 1998); this event is correlated with a consistent and dynamic mammary growth and the milking start (Kitts, 1985). In goats, circulating cortisol concentrations are high during parturition and peak with the expulsion of the first kid; the observation of greater cortisol concentrations in goats with dystocia and retrained placenta suggests their higher stress level (Hydbring et al, 1999; Probo et al, 2011).
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