In vivo Fertilizing Capacity of Deep Frozen Boar Semen Packaged in Plastic Bags and Maxi‐Straws

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Abstract
Pooled ejaculates from six fertile boars were frozen under controlled conditions in Teflon(R) FEP-film plastic bags (5 ml) and maxi-straws (2.5 ml) using 3 % glycerol as cryoprotectant. The percentages of both post-thaw motility and normal apical ridges were significantly higher (P < 0.001) for the bags (54.5 and 75 %) than for the maxi-straws (40.1 and 59.4 %) respectively. For evaluation of the in vivo fertilizing capacity of the frozen-thawed spermatozoa, 26 gilts were inseminated once 24 h after the first observation of standing reflex in their second oestrus, with 5 ml of semen (containing 5 billion spermatozoa) reconstituted in 80 ml of BTS from either bags or maxi-straws. Ova were recovered from the oviducts/uteri 2-4 days following insemination and examined for cleavage and sperm binding to the zona pellucida (ZP). Significantly higher rates (P < 0.02) of fertilized ova were found in the bag-inseminated (75 %) than in maxi-straw inseminated gilts (63%); and similarly their ova had significantly more spermatozoa in the ZP, irrespective of whether they were fertilized or non-fertilized. This study confirmed that the plastic bags are suitable and may be used for packaging single insemination doses of deep frozen boar semen for routine A.I. work.