Abstract
The objective of this study was to evaluate effect of the season on the yield and viability of embryos recovered from superovulated and flushed Holstein cows (n = 56). The embryo recovery rate (ERR, %) was determined as the proportion of totally flushed embryos (TFE, n) to the number of corpora lutea detected. The embryos were evaluated as transferable (TRANS) or non-transferable and analysed for occurrence of apoptotic cells (T+, TUNEL- index) as well as actin cytoskeleton quality (ACG). TFE and ERR were the highest during spring vs summer (149 embryos, 59.6% vs 20 embryos, 37%; P < 0.001), while they insignificantly differed in autumn (57 embryos, 48.3%). The autumn embryos presented a higher proportion of TRANS (P < 0.05, +10.56% vs spring; +18.94% vs summer). The occurrence of apoptosis in these embryos was lower (-1.38 T+ cells and -1.75% T-index; P < 0.05) and the percentage of the best ACG was higher (+35%; P < 0.05). These findings identified autumn as the best season for collection of high-quality bovine embryos.
Highlights
Embryo transfer (ET) represents a major breeding procedure accelerating genetic progress, mainly in cattle breeding (Merton et al, 2003)
88.89% of the cows positively responded to superovulation, only 80.00% in the summer and the highest proportion was recorded in the autumn, 89.47%
Stádník et al (2013) reported a growing trend of embryo transfer (ET) performed worldwide, significantly reduced ET cycles have been recorded in the Czech Republic
Summary
Embryo transfer (ET) represents a major breeding procedure accelerating genetic progress, mainly in cattle breeding (Merton et al, 2003). The most serious problem in ET is the unreliability of the superovulation reaction (Szabari et al, 2008) characterized by high variability influenced by many internal factors related to the physiological condition of the animal, such as age (Callesen et al, 1996), breed, genetic differences (Kafi and McGowan, 1997), or ovarian size (Hegedüšová and Dufek, 2012). External factors influencing the response to superovulation include nutrition (Berry et al, 2003), subclinical infections (Leroy et al, 2005), lactation (Walsh et al, 2011), repeated superovulation and season (Silva et al, 2009). According to Wolfenson et al (2000) and Sartori et al (2002), season is one of the main factors influencing the superovulation response. There are clear seasonal effects decreasing fertility in the warmer months from June to July (Silva et al, 2009). De Rensis and Scaramuzzi (2003) described
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
