Different physical and physiological parameters may be used to determine ovulation time in sows. In the present study, we analysed the ear and vulvar skin temperature fluctuations, and the changes in genital electrical resistance, at a distance of 4, 8 and 12 cm from the vulva during oestrus in order to predict the time of ovulation. Multiparous sows were checked by transrectal real-time ultrasonography and luteinising hormone (LH) plasma concentration was determined. Temperature was measured using a thermoprecision infrared thermometer, and the electrical resistance was measured with a commercial resistance probe. All measurements were carried out every 12 hours from one day after the weaning to three days after oestrus onset. Skin temperature showed significant difference around periovulatory period. The electrical resistance at 4 cm from the vulva showed marked changes during oestrus, which were different from those described at 8 and 12 cm from the vulva. At 12 hours before ovulation time, skin temperature decreased significantly, and negative correlation (P<0.05) was found between vulvar skin temperature and vaginal resistance. There was no relationship between skin temperature, electrical resistance and LH plasma concentration. The measurement of several physiological traits may provide more accurate predictions of the moment of ovulation.
To improve the boar sperm cryopreservation process, the influence of the sugar (lactose, trehalose) source and the cryoprotectant [glycerol, dimethylformamide (DMF)] on the success of freezing was investigated. Sperm samples were frozen in one of six extenders: lactose plus 3% glycerol (LG); lactose plus 1.5% glycerol and 1.5% DMF (LGD); lactose plus 3% DMF (LD); trehalose plus 3% glycerol (TG); trehalose plus 1.5% glycerol and 1.5% DMF (TGD); trehalose plus 3% DMF (TD). Effects on motility, viability, acrosome integrity and hypoosmotic test (HOST) were measured. The results showed that extender containing 3% glycerol retained the highest motility percentages. In regard to viability and acrosome integrity, all extenders yielded similar rates except for the decreasing values of TD. Endosmosis was diminished in TD and LD at 2 h (P = 0.0018), as compared with the others. The results of the study demonstrated that the use of DMF as a cryoprotectant adversely affected boar sperm quality after cryopreservation.
In this study, we investigated the protective ability of the addition of two antioxidant herb extracts, mate tea and lemon balm, on boar epididymal frozen-thawed spermatozoa quality. Testes from mature boars were collected at local slaughterhouse, and sperm samples from epididymis were recovered by flushing. Spermatozoa were cryopreserved in lactose-egg yolk buffer supplemented with various concentrations of lemon balm and mate tea (0, 2.5, 5 and 10 g l(-1) ) using the straw-freezing procedure. Motion parameters, acrosome and plasma membrane integrity, lipoperoxidation levels and DNA oxidative damage (8-hydroxy-2'-deoxyguanosine base lesion) were evaluated. There were no differences among experimental groups with regard to motility characteristics, viability, acrosome and plasma membrane integrity; however, the highest concentration of lemon balm produced significant (P < 0.05) improvement in curvilinear trajectory, straightness and amplitude of lateral head displacement after thawing. The supplementation of freezing extender with mate tea and lemon balm reduced sperm lipid membrane peroxidation, and only mate tea protected DNA against oxidative damage during cryopreservation at 120 min post-thawing (P < 0.05). Mate tea experimental extender at concentration of 10 g l(-1) showed the lowest percentage of sperm oxidised DNA and malondialdehyde generation; thus, mate tea is a potential candidate such as antioxidant compound on boar sperm cryopreservation medium.
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