Fertility response of artificial insemination methods in sheep with fresh and frozen-thawed semen

Abstract

The aim of this study was to evaluate the fertility response of artificial insemination (AI) methods with fresh and frozen sperm in sheep. In experiment 1, one hundred and fifty fat tailed Zandi ewes were assigned into 3 equal groups and inseminated with three AI methods consisting of vaginal, laparoscopic and trans-cervical AI with fresh semen. In experiment 2, a factorial study (3 AI methods × 2 extenders) was used to analyze the effects of three AI methods and two freezing extenders containing soybean lecithin (SL) or Egg yolk (EY) on reproductive performance of 300 fat tailed Zandi ewes. Also, total motility, progressive motility, viability and lipid peroxidation of semen were evaluated after freeze-thawing in two extenders. In result, there was no significant difference among three AI methods when fresh semen was used. In experiment 2, the highest percentage of pregnancy rate, parturition rate and lambing rate were obtained in laparoscopic AI group (P < 0.05). Although pregnancy rate, parturition rate and lambing rate in trans-cervical group were higher (P < 0.05) than vaginal group, the results were not as high as laparoscopic group. No difference was observed between SL and EY extenders and their performance was close to each other. It can be concluded that although no difference was observed on reproductive performance for fresh semen, trans-cervical AI was more efficient than vaginal method when frozen-thawed semen was used, but its efficiency was not as high as laparoscopic method. Also, SL extender can be an efficient alternative extender to preserve ram sperm during cryopreservation procedure without adverse effects of EY.

Current challenges in sheep artificial insemination: A particular insight

“…With frozen‐thawed semen, cervical insemination rates are generally low and are obtained from unrepresentative experimental studies (few inseminations) under very diverse conditions, which makes it difficult to transfer this practice to a productive sector: 4% (Masoudi et al., ), 28% (Gil, Rodriguez‐Irazoqui, Lundeheim, Söderquist, & Rodríguez‐Martínez, ) and 13% (Byrne et al., ). Exceptionally, Paulenz et al.…”

“…The membrane protectors classically used to preserve refrigerated sperm have been skim milk and egg yolk. For ovine semen stored for short periods (<12 hr – 15°C), milk: 66% (Paulenz, Söderquist, Ådnøy, Fossen, & Berg, ), egg yolk: 56% (Masoudi et al., ) or both together 70% (Donovan et al., ) offer good fertility results.…”

“…This technique offers acceptable and uniform fertility rates in the use of frozen‐thawed sperm samples: 61% (Windsor et al., ); 62%, (Fair et al., ); 60% (Anel et al., ); and 64% (Masoudi et al., ). LAI was designed to be used with frozen‐thawed sperm samples and oestrous synchronization (fixed‐time insemination); however, it has also been used with refrigerated sperm samples and/or in natural oestrus, with results similar to those that are obtained with frozen‐thawed samples (Aké‐Villanueva et al., ).…”

Cervical dilation and improvement of reproductive performance in fat-tailed ewes via cervical dilator treatments

“…This answer may be explained by effects of oxytocin that initiates collagenolytic enzyme process resulting in cervical dilation [19]. Previous studies showed that E 2 +OT or only OT [13,[20][21][22] caused cervical dilation in ewes. It has been proven that 400 IU OT led to dilation of cervix, but the injection of this amount of hormone right before the insemination may have some problems.…”

Alpha-tocopherol improves frozen-thawed sperm quality by reducing hydrogen peroxide during cryopreservation of bull semen

“…Semen cryopreservation has allowed specific opportunities for conservation of genetic resources through sperm banks, guarantee of a constant commercial supply of semen, and collaboration in breed improvement programs by artificial insemination (Bucak et al, 2007;Masoudi et al, 2017). Semen cryopreservation may lead to oxidative, chemical and physical damages on sperm membrane leading to reduction of sperm viability and fertility (Evans et al, 1987;Watson, 2000;Emamverdi et al, 2014;Najafi et al, 2014a;Sarıözkan et al, 2015).…”