Annual concentrations of thyroxin and progesterone in Karagouniko and Chios ewes


D. KANTAS (Δ. ΚΑΝΤΑΣ)
E. VALASI (Ε. ΒΑΛΑΣΗ)
Th. TSILIGIANNI (Θ. ΤΣΙΛΙΓΙΑΝΝΗ)
E. NTOVOLOU (Ε. ΝΤΟΒΟΛΟΥ)
G. RIGAS (Γ. ΡΗΓΑΣ)
Abstract

The circannual secretion of progesterone and thyroxin of two indigenous sheep breeds (Chios and Karagouniko, each n=10) with different reproductive pattern was investigated. Blood samples were collected weekly and the serum hormone's concentration was assayed by RIA. Between breeds, no difference was detected in the mean annual thyroxin concentration. Similarly, no differences were detected within breeds in the mean thyroxin concentrations for the periods of increasing and decreasing daylight. Clear thyroxin peaks were detected in both breeds a month or so prior to the transition to anestrus period; these peaks were higher in the Karagouniko breed. Breeding season duration was clearly shorter in Karagouniko in comparison with that of Chios; in the later breed many animals had substantially short anestrus. These results give strong indications that thyroid activity has a catalytic role in the regulation of the reproductive period in ewes.

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Riferimenti bibliografici
Adams VL, Goodman RL, Salm AK, Coolen LM, Karsch FJ, Lehman MN, (2006). Morphological plasticity in the neural circuitry responsible for seasonal breeding in the ewe. Endocrinology 147, 4843-51.
Billings HJ, Viguie C, Karsch FJ, Goodman RL, Connors JM, Anderson GM, (2002). Temporal requirements of thyroid hormones for seasonal changes in LH secretion. Endocrinology 143,2618-25.
Boyazoglou JG, (1991). Milk breeds of sheep. In: Maijala Κ (ed) Genetic resources of pig, sheep and goats. Amsterdam, Elsevier Science Pub BV 243-255.
Dahl GE, Evans NP, Thrun LA, Karsch FJ, (1995). Thyroxine is permissive to seasonal transitions in reproductive neuroendocrine activity in the ewe. Biol Reprod 52, 690-6.
Forcada F, Abecia JA, (2006). The effect of nutrition on the seasonality of reproduction in ewes. Reprod Nutr Dev 46,355-65.
Forcada F, Zuniga Ο, Abecia JA, (2002). The role of nutrition in the regulation of LH secretion during anestrus by the serotoninergic and dopaminergic systems in Mediterranean ewes treated with melatonin. Theriogenology 58,1303-13.
Karsch FJ, Dahl GE, Evans NP, Manning JM, Mayfield KP, Moenter SM, Foster DL, (1993). Seasonal changes in gonadotropin- releasing hormone secretion in the ewe: alteration in response to the negative feedback action of estradiol. Biol Reprod 49,1377-83.
Kaynard AH, Karsch FJ, (1988). Hypophyseal actions of pulsatile gonadotropin-releasing hormone in the ewe: development and application of a new experimental model. Neuroendocrinology 48, 287-95.
Lehman MN, Goodman RL, Karsch FJ, Jackson GL, Berriman SJ, Jansen HT, (1997). The GnRH system of seasonal breeders: anatomy and plasticity. Brain Res Bull 44,445-57.
Thrun LA, Dahl GE, Evans NP, Karsch FJ, (1996). Time-course of thyroid hormone involvement in the development of anestrus in the ewe. Biol Reprod 55,833-7.
Thrun LA, Dahl GE, Evans NP, Karsch FJ, (1997). A criticai period for thyroid hormone action on seasonal changes in reproductive neuroendocrine function in the ewe. Endocrinology 138,3402-9.
Viguie C, Battaglia DF, Krasa HB, Thrun LA, Karsch FJ, (1999). Thyroid hormones act primarily within the brain to promote the seasonal inhibition of luteinizing hormone secretion in the ewe. Endocrinology 140,1111-7.
Webster JR, Moenter SM, Woodfill CJ, Karsch FJ, (1991). Role of the thyroid gland in seasonal reproduction. II. Thyroxine allows a season-specific suppression of gonadotropin secretion in sheep. Endocrinology 129,176-83.
Βοσνιακού A. (1983). Συγκριτική μελέτη της ετήσιας οιστρικής και ωοθηκικής δραστηριότητας των ελληνικών φυλών προβάτων Χίου, Καραγκούνικης και Σερρών. Διδακτορική Διατριβή, Θεσσαλονίκη.
Μενεγάτος Ι., Καλογιάννης Δ., Λαϊνάς Θ., Νοικοκύρης Π., Δεληγιάννης Κ., Νικολάου Ε., (1994). Επίπεδα Θυροξίνης κατά τη διάρκεια του έτους σε προβατίνες των φυλών Καραγκούνικης και Ορεινής της Ηπείρου. Δελτίον Ελλ. Κτην. Εταιρείας, 45(1):20-24.
Μενεγάτος Ι., Νικολάου Ε., Καλογιάννης Δ., Μάντζιος Α., Στοφόρος Ε., (1995). Η ετήσια ωοθηκική δραστηριότητα προβατίνων της ορεινής φυλής Ηπείρου (Μποΰτσικο) σε συνθήκες εντατικής εκτροφής. Δελτίον Ελλ. Κτην. Εταιρείας, 46(1): 39-46
Μενεγάτος Ι., Χαδιώ Σ., Δοσόπουλος Β., Καλογιάννης Δ., Ξυλούρη Ε. (2003). Ωοθηκική και θυρεοειδική δραστηριότητα προβατίνων φυλής Lacaune στην Ελλάδα κατά τη διάρκεια του έτους. Περιοδικό της Ελλ. Κτην. Εταιρείας, 54(3): 209-220
Μιχαηλίδης Ι. (1986). Αναπαραγωγικοί παράμετροι προβάτων φυλής Χίου και Κΰμης. Διδακτορική Διατριβή, Θεσσαλονίκη.
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