Feed Planet 84 - March 2026

FEED PLANET • MARCH - MART 2026 FEED PLANET • MARCH - MART 2026 44 45 C vitamini ise suda çözünebilen bir serbest radikal temiz- leyicisidir. Ayrıca, GSH veya indirgeyici eşdeğerler bağış- layabilen bileşiklerle birlikte hücre zarlarında E vitaminini yeniden oluşturur. C vitamini, lipit peroksidasyon zincir reak- siyonunu sonlandırmak için lipit radikaline bir elektron vere- rek askorbat radikaline dönüşür (Niki, 1991; C.Oh vd. 2010). SONUÇ Geçiş dönemi, süt sığırlarında metabolik yükün arttığı, ne- gatif enerji dengesinin geliştiği ve buna bağlı olarak reaktif oksijen türlerinin (ROS) üretiminin yükseldiği kritik bir dö- nemdir. Artan ROS üretimi, antioksidan savunma sistemleri ile dengelenemediğinde oksidatif strese yol açmakta; bu durum mastitis, ketozis, yağlı karaciğer, laminitis ve üreme bozuklukları gibi hastalıkların gelişme riskini artırmaktadır. Oksidatif stres, hücresel düzeyde lipit peroksidasyonu, pro- tein hasarı ve DNA hasarına neden olarak doku fonksiyon- larını olumsuz etkilemektedir. Bu nedenle geçiş döneminde antioksidan savunmanın güçlendirilmesi hem metabolik hastalıkların önlenmesi hem de süt verimi ve üreme performansının sürdürülebilmesi açısından büyük önem taşımaktadır. Antioksidan etkili bit- kisel ekstraktlar, Vitamin E, vitamin C, selenyum ve yüksek biyoyararlanıma sahip bakır, çinko, mangan gibi vitamin ve minerallerin yeterli düzeyde sağlanması; ayrıca rasyonun enerji dengesinin doğru düzenlenmesi, oksidatif stresin olumsuz etkilerini azaltmada etkili stratejiler olarak öneril- mektedir. Gelecekte yapılacak çalışmaların, farklı antiok- sidan kombinasyonlarının geçiş dönemi sığırlarında klinik sonuçlara etkisini karşılaştırmalı olarak incelemesi gerektiği sonucuna varılmıştır. water-soluble free radical scavenger that also regenerates vitamin E in cell membranes in conjunction with compounds capable of donating GSH or reducing equivalents. In termi- nating the lipid peroxidation chain reaction, vitamin C dona- tes an electron to the lipid radical and is thereby converted to an ascorbate radical (C.Oh et al., 2010; Niki, 1991). CONCLUSION The transition period is a critical phase in dairy cows during which metabolic load increases, negative energy balance develops, and reactive oxygen species (ROS) pro- duction rises accordingly. When increased ROS produc- tion cannot be adequately offset by antioxidant defense systems, oxidative stress ensues, raising the risk of dise- ases such as mastitis, ketosis, fatty liver, laminitis and rep- roductive disorders. At the cellular level, oxidative stress adversely affects tissue function through lipid peroxidation, protein damage and DNA damage. Strengthening antioxidant defenses during the transition period is therefore of critical importance, both for the pre- vention of metabolic diseases and for sustaining milk yield and reproductive performance. Ensuring adequate levels of antioxidant plant extracts, vitamin E, vitamin C, selenium, and highly bioavailable minerals such as copper, zinc and manganese — together with appropriate regulation of die- tary energy balance — are recommended as effective stra- tegies for mitigating the adverse effects of oxidative stress. It is concluded that future studies should comparatively evaluate the effects of different antioxidant combinations on clinical outcomes in transition cows. Arslan C, Tufan T. [Feeding the transition dairy cow II. Metabolic disorders seen in this period and prevention through feeding]. 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