Sütçü İneklerde Foliküler Gelişimin İndüklenmesi: Güncel Stratejiler, Vazoaktif Mekanizmalar ve Sürü Düzeyinde Protokol Seçimi

Abstract

Yüksek verimli süt sığırı işletmelerinde üreme verimliliği, postpartum dönemde belirginleşen foliküler dinamiklerdeki aksamalardan en çok etkilenen parametrelerden biridir. Negatif enerji dengesi, artmış steroid katabolizması ve baskılanmış LH pulsatilitesi; dominant folikül seçimini geciktirmekte, ilk postpartum ovulasyonu ertelemekte ve oosit kalitesini düşürmektedir. Bu derleme, ineklerde foliküler dalga fizyolojisini güncel veriler ışığında ele alarak mevcut hormonal indüksiyon protokollerini -GnRH bazlı yaklaşımlar (Ovsynch, Double-Ovsynch ve presenkronizasyon varyantları), progesteron-östradiol ve eCG destekli protokoller- karşılaştırmalı olarak değerlendirmekte; ayrıca giderek daha fazla ilgi gören bir düzenleyici alan olarak intraovaryan sempatoadrenerjik sistemi tartışmaktadır. Özellikle, ovulasyonu izleyen erken dönemde intrauterin isoproterenol uygulamasının utero-ovaryan hemodinami, foliküler gelişim ve bazı endokrin göstergeler üzerinde etkiler oluşturabildiği bildirilmekte; bu etkilerin β2-adrenerjik reseptörler ve cAMP-PKA aracılı yolaklar aracılığıyla gonadotropin duyarlılığını etkileyebileceği öne sürülmektedir. Derlemede ayrıca vücut kondisyon skoru, anovulasyon prevalansı, antral folikül sayısı ve Anti-Müllerian Hormon gibi göstergelerin sürü düzeyinde protokol seçimine katkısı da değerlendirilmektedir. Mevcut veriler, sütçü ineklerde foliküler gelişimin yönetiminde tek tip protokol anlayışının her zaman yeterli olmadığını; sürüye özgü biyolojik çeşitliliğin sistematik biçimde değerlendirilerek protokol seçiminin bireyselleştirilmesinin üreme verimliliğine katkı sağlayabileceğini ortaya koymaktadır.

Keywords

• Follicular Development
• Synchronization
• β-adrenergic signaling
• Postpartum
• Dairy cows

Follicular Development in Cattle: Synchronization Protocols, Vasoactive Mechanisms, and Herd-Level Selection

Abstract

Reproductive efficiency in high-producing dairy herds is strongly affected by disruptions in follicular dynamics, which become particularly evident during the postpartum period. Negative energy balance, increased steroid catabolism, and suppressed luteinizing hormone (LH) pulsatility delay dominant follicle selection, postpone the first postpartum ovulation, and compromise oocyte quality. This review examines follicular wave physiology in cows based on current evidence and comparatively evaluates existing hormonal induction protocols, including GnRH-based approaches such as Ovsynch, Double-Ovsynch, and presynchronization variants, as well as progesterone-estradiol- and eCG-supported protocols. It also discusses the intraovarian sympathoadrenergic system as an emerging but as yet incompletely characterized regulatory domain, noting that preliminary in vivo evidence suggests β-adrenergic stimulation may influence utero-ovarian hemodynamics and follicular development, though the clinical relevance of these findings remains to be established. The review further considers how indicators such as body condition score, anovulation prevalence, antral follicle count, and anti-Müllerian hormone may contribute to herd-level protocol selection. Overall, the available evidence indicates that a uniform protocol-based approach may not always be sufficient for managing follicular development in dairy cows. Instead, systematic assessment of herd-specific biological variation may support more individualized protocol selection and thereby contribute to improved reproductive efficiency.

Keywords

• β-adrenergic signaling
• dairy cows
• follicular development
• postpartum
• synchronization.

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