1.Factors affecting the success of resynchronization protocols with or without progesterone supplementation in dairy cows.
Annette FORRO ; Georgios TSOUSIS ; Nicola BEINDORFF ; Ahmad Reza SHARIFI ; Christos BROZOS ; Heinrich BOLLWEIN
Journal of Veterinary Science 2015;16(1):121-126
The objective of this study was to investigate factors that influence the success of resynchronization protocols for bovines with and without progesterone supplementation. Cow synchronized and not found pregnant were randomly assigned to two resynchronization protocols: ovsynch without progesterone (P4) supplementation (n = 66) or with exogenous P4 administered from Days 0 to 7 (n = 67). Progesterone levels were measured on Days 0 and 7 of these protocols as well as 4 and 5 days post-insemination. Progesterone supplementation raised the P4 levels on Day 7 (p < 0.05), but had no overall effect on resynchronization rates (RRs) or pregnancy per artificial insemination (P/AI). However, cows with Body Condition Score (BCS) > 3.5 had increased P/AI values while cows with BCS < 2.75 had decreased P/AI rates after P4 supplementation. Primiparous cows had higher P4 values on Day 7 than pluriparous animals (p = 0.04) and tended to have higher RRs (p = 0.06). Results of this study indicate that progesterone supplementation in resynchronization protocols has minimal effects on outcomes. Parity had an effect on the levels of circulating progesterone at initiation of the protocol, which in turn influenced the RR.
Animals
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Cattle/*physiology
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Dinoprost/administration & dosage/*pharmacology
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Estrus Synchronization/*drug effects/methods
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Female
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Fertility Agents/administration & dosage/pharmacology
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Gonadotropin-Releasing Hormone/administration & dosage/*pharmacology
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Insemination, Artificial/veterinary
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Ovulation/drug effects
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Pregnancy
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Progesterone/administration & dosage/*pharmacology
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Tromethamine/administration & dosage/*pharmacology
2.Effect of oxytocin infusion on luteal blood flow and progesterone secretion in dairy cattle.
Christos N BROZOS ; Metin S PANCARCI ; Javier VALENCIA ; Nikola BEINDORFF ; Georgios TSOUSIS ; Evaggelos KIOSSIS ; Heinrich BOLLWEIN
Journal of Veterinary Science 2012;13(1):67-71
The objective of this study was to investigate the effects of oxytocin infusion on corpus luteum (CL) function during early to mid-diestrus by measuring luteal size (LS) and luteal blood flow (LBF) along with plasma levels of progesterone (P4) and prostaglandin metabolites (13,14-dihydro-15-keto-prostaglandin F2alpha, PGFM). On day (D) 7 of the estrus cycle (D1 = ovulation), seven cows received 100 IU of oxytocin (OXY) or placebo (PL) following a Latin square design. LS and LBF increased in both groups over time and no differences were observed between the groups. PGFM did not differ either within the groups over time or between the groups at any time point. P4 of the OXY group was higher compared to that of the the PL group 360 min after the infusion (p = 0.01) and tended to be higher at the time points 450 min, 48 h, and 72 h (all p = 0.08). Results from this study support the hypothesis that OXY is not directly involved in the mechanism(s) governing blood flow of the CL and has no remarkable effects either on luteal size or P4 and PGFM plasma levels. Further investigation is needed to elucidate the role of OXY in CL blood flow during early and late luteal phases.
Animals
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Cattle/*physiology
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Corpus Luteum/blood supply/*drug effects/secretion/ultrasonography
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Dinoprost/analogs & derivatives/blood
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Estrous Cycle/*drug effects/physiology
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Female
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Immunoenzyme Techniques/veterinary
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Organ Size/physiology
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Oxytocin/*pharmacology
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Progesterone/blood/*secretion
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Random Allocation
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Ultrasonography, Doppler, Color/veterinary