No abstract

Heat stress is a major factor contributing to low fertility of dairy cows with a great economic impact in dairy industry. Heat-stressed dairy cows usually have reduced nutrient intake, resulting in a higher degree of negative energy balance (NEB). The aim of this study was to investigate the seasonal thermal effect on lipid metabolism, antioxidant activity and reproductive performance in dairy cows. Thirty-two healthy dairy heifers were included in the study. According to the ambient temperature, animals were divided into two groups: winter (N = 14) and summer season (N = 18). Metabolic parameters, paraoxonase-1 (PON1) activity and total antioxidant status (TAS) were monitored at the time of insemination (basal values) and from 1 week before until 8 weeks after calving. Number of services per conception and calving-to-conception (CC) interval were calculated from the farm recording data. Serum triglyceride, non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB) concentrations were significantly increased after calving in summer compared to winter, indicating higher degree of NEB in cows during summer. PON1 activity was significantly decreased after calving in both summer and winter group. TAS concentration was significantly lower in summer than that in winter. A significantly higher number of services were needed for conception in summer compared to winter, and CC interval was significantly longer in summer than that in winter as well. Additionally, reproductive performance significantly correlated with the severity of NEB, suggesting that lipid mobilization and lower antioxidant status contributed to poor reproduction ability in dairy cows during hot months.

The resazurin reduction assay depends on the ability of metabolically active cells to reduce the resazurin redox dye to resorufin. In the present study we applied and made a diagnostic evaluation of a spectrophotometric application of the resazurin reduction assay to assess the colour change of resazurin reduction in butanol extracted colour to evaluate boar semen quality. Forty-one samples of boar semen from various breeds were included in the study. The absorption peaks for resazurin and resorufin were found to be 610 and 575 nm, respectively. Absorbance at 610 nm, where the minimum overlap of the two peaks was observed, was used in further analysis. Spearman rank correlation analysis was used to determine the correlation between the resazurin reduction assay and various semen parameters. The highest correlations were observed with the concentration of motile spermatozoa (r = -0.841; p < 0.001), sperm concentration (r = -0.833; p < 0.001), sperm index (-0.826; p < 0.001) and concentration of viable spermatozoa (r = -0.763; p < 0.001). Sensitivity and specificity, at 94.1 and 91.7%, respectively, indicate that the present test is highly accurate in discriminating between the samples according to the sperm index. When motile sperm concentration was used to distinguish between good and poor samples, high sensitivity (93.6%) was also found, whereas the test was only moderately, 80%, specific. The stability of butanol extracts in terms of A610 at different times of measurement confirmed that the resazurin reduction could be spectrophotometrically measured within 7 days from the time of assay performance, making the assay much more useful. Based on these results, the assay could be used as an additional tool for evaluating the quality of boar semen.

BackgroundGrowing evidence indicates that macro- and microelements in the seminal plasma of humans and various domestic animals are of great importance due to their roles in sperm metabolism, function, survival and oxidative stress. In the present study, we therefore determined the concentrations of macro- and microelements in fresh boar seminal plasma and their relation to sperm quality parameters after 3 days of liquid storage was assessed. Twenty ejaculates from eight boars were collected, and semen volume, concentration, sperm motility, morphology, tail membrane integrity, plasma membrane permeability, mitochondrial membrane potential and DNA fragmentation were determined on the day of collection (day 0) and day 3 (72 h) of storage at 15–17 °C. Seminal plasma was separated and the concentrations of macroelements (Na, K, Ca, and Mg) and microelements (Cu, Fe, Zn and Se) were determined.ResultsAfter 3 days of storage Se levels correlated significantly with sperm motility, progressive motility and morphology, all of which are routinely used for semen evaluation. On day 3, Se levels also correlated with tail membrane integrity, viability and intact DNA (P < 0.05). The correlation coefficients showed that mitochondrial function was better preserved at higher levels of Zn, while higher levels of Cu decreased mitochondrial function, but led to the better preservation of DNA. It was also evident that higher levels of Fe were associated with higher proportions of live spermatozoa and of spermatozoa with normal morphology after 3 days of storage (P < 0.05), while higher levels of Ca and Mg in fresh seminal plasma were associated with lower percentages of progressive motile spermatozoa and with a decreased proportion of spermatozoa with intact DNA (P < 0.05). Multivariate analysis including microelements showed that Se significantly affected sperm quality parameters, mentioned above, after 3 days of storage.ConclusionsMacro- and microelements were associated with boar sperm quality and may be important biomarkers of boar sperm quality after liquid storage. Our results demonstrate that the evaluation of Se in fresh boar seminal plasma can serve as an additional tool in predicting sperm quality after storage.

Superoxide dismutase (SOD), total antioxidant capacity (TAC), and thiobarbituric acid reactive substances (TBARS) in seminal plasma were evaluated on the basis of receiver operating characteristics (ROC) analysis as predictors for distinguishing satisfactory from unsatisfactory boar semen samples after storage. SOD on day 0 correlated significantly with progressive motility (r = −0.686; P < 0.05) and viability (r = −0.513; P < 0.05) after storage; TBARS correlated only with motility (r = −0.480; P < 0.05). Semen samples that, after 3 days of storage, fulfilled all criteria for semen characteristics (viability > 85%, motility > 70%, progressive motility > 25%, and normal morphology > 50%) had significantly lower SOD levels on the day 0 than those with at least one criterion not fulfilled (P < 0.05) following storage. SOD levels of less than 1.05 U/mL predicted with 87.5% accuracy that fresh semen will suit the requirements for satisfactory semen characteristics after storage, while semen with SOD levels higher than 1.05 U/mL will not fulfill with 100% accuracy at least one semen characteristic after storage. These results support the proposal that SOD in fresh boar semen can be used as a predictor of semen quality after storage.