Influence of the coincubation of post-thawed bull semen with elevated ß-hydroxybutyrate concentrations on sperm characteristics.

In this study, the relationships between post-thaw bull sperm characteristics and hyperketonemic conditions after coincubation with cow plasma or media were determined to investigate if such a condition could affect bull sperm characteristics. Two experiments were conducted. In experiment 1, blood samples were collected from 31 cows to prepare plasma. Cows were independently categorized into two groups according to plasma ß-hydroxybutyrate (BHB) concentrations (above or below 1.2 mM). Thawed bull semen was diluted and incubated with diluted plasma; motility parameters were evaluated using Computer Assisted Semen Analysis (CASA). In experiment 2, a pooled sample of thawed semen was diluted and divided into three aliquots: without BHB (control) and treated with either 1.2 mM (1.2) or 3 mM (3) BHB. In addition to motility, flow cytometric analyses were carried out. In experiment 1, the overall motility decreased significantly in plasma containing high (≥1.2 mM) BHB compared to plasma containing low (<1.2 mM) BHB. In experiment 2, the overall motility tended to be lower in BHB (3 mM)-supplemented samples. The supplementation of 3 mM BHB increased the proportion of live superoxide-positive sperm and sperm with high mitochondrial potential, while the DNA fragmentation index decreased.

Association of pregnancy per artificial insemination with gonadotropin-releasing hormone and human chorionic gonadotropin administered during the luteal phase after artificial insemination in dairy cows: A meta-analysis.

One strategy for improving fertility in cattle is administration of GnRH or human chorionic gonadotropin (hCG) during the luteal phase, which increases progesterone (P4) secretion and delays luteolysis. To provide an overview of how GnRH or hCG treatment between 4 and 15 d after artificial insemination (AI) improves pregnancy per AI (P/AI) in cows, a meta-analysis was performed on 107 different trials from 52 publications. Data from 18,082 treated cows and 18,385 untreated controls were meta-analyzed. The meta-analysis explained the relative risk for P/AI with GnRH or hCG treatment under various circumstances. The results did not show any difference in P/AI between cows treated with hCG and cows treated with GnRH. Compared with no treatment, treatment with GnRH or hCG improved the chances of P/AI in cows with very poor (<30%) and poor (30.1 to 45%) fertility, whereas treatment did not benefit cows with very good fertility (>60.1%). Moreover, treatment with GnRH and hCG improved the chances of P/AI in primiparous cows. The improvement was much better in primiparous cows with very low fertility. Treatment with buserelin at a dose above 10 µg and with hCG at a dose above 2,500 IU was associated with increased chances of P/AI compared with lower doses. Treatment with GnRH 10 d after AI was also associated with increased chances of P/AI compared with earlier treatment. The present meta-analysis showed that the use of GnRH and hCG after AI should be focused on cows expected to have low or moderate fertility. Day and dose of treatment have to be considered as well.

Non-steroidal anti-inflammatory drugs at embryo transfer on pregnancy rates in cows: A meta-analysis.

Non-steroidal anti-inflammatory drugs (NSAIDs) at the time of embryo transfer (ET) are commonly used to improve pregnancy rates in cows. A meta-analysis was conducted on 16 trials from 9 publications involving control (n = 2335) and NSAID-treated (n = 2849) cows. The meta-analysis explained the relative risk (RR) with its 95% confidence interval (CI) for pregnancy per embryo transfer (P/ET) after NSAID treatment under various circumstances. NSAID treatment with was associated on average with a 15% higher P/ET compared to no treatment (RR = 1.15, 95% CI = 1.07 to 1.2). The results also highlight that the use of NSAIDs at the time of ET was particularly effective in cows with difficulty in passing the catheter from the cervix during ET, with 71% more likely P/ET (RR = 1.71, 95% CI = 1.07 to 2.74) with the use of NSAIDs for these cows compared to other cows. The data were too limited to analyse the influence of NSAID molecules (flunixin meglumine [FM] and meloxicam), cyclooxygenase (COX) inhibitor type (non-selective COX inhibitor [both COX-1 and COX-2] and selective COX inhibitor [only COX-2]), embryo processing (embryo production, embryo conservation and embryo quality), stress, synchronization, breed and parity on the relationship between NSAIDs and P/ET.