ABSTRACT
Introduction: The development of an effective extender is important for semen preservation and the artificial insemination (AI) industry. This study demonstrates the beneficial effect of zinc oxide nanoparticles (ZnO-NPs) as an additive to semen extenders to improve semen quality, fertility, and antibacterial activity during liquid preservation in a boar model. Methods: Initially, to find out the safe concentration of ZnO-NPs in sperm cells, a wide range of ZnO-NP concentrations (0, 5, 10, 50, 100, 500, and 1,000 µM) were co-incubated with sperm at 37°C for a cytotoxic study. These NP concentrations were compared to their salt control zinc acetate (ZA) at the same concentrations and to a control group. The effect of the different concentrations of ZnO-NPs on sperm motility, membrane integrity, mitochondrial membrane potential (MMP), and apoptosis was assessed. Accordingly, the non-toxic dose was selected and supplemented in MODENA extender to determine its beneficial effect on the boar semen parameters mentioned and the lipid peroxidation (LPO) levels during liquid preservation at 16°C for 6 days. The non-cytotoxic dosage was subsequently chosen for AI, fertility investigations, and the evaluation of the antibacterial efficacy of ZnO-NPs during preservation hours. An antibacterial study of ZnO-NPs and its salt control at doses of 10 µM and 50 µM was carried out by the colony forming unit (CFU) method. Results and discussion: The cytotoxic study revealed that 5, 10, and 50 µM of ZnO-NPs are safe. Consequently, semen preserved in the MODENA extender, incorporating the non-toxic dose, exhibited 10 and 50 µM ZnO-NPs as the optimal concentrations for beneficial outcomes during liquid preservation at 16°C. ZnO-NPs of 10 µM concentration resulted in a significantly (p < 0.05) improved conception rate of 86.95% compared to the control of 73.13%. ZnO-NPs of 10 and 50 µM concentrations exhibit potent antimicrobial action by reducing the number of colonies formed with days of preservation in comparison to the negative control. The investigation concluded that the incorporation of 10 µM ZnO-NPs led to enhancements in sperm motility, membrane integrity, and MMP, attributed to a reduction in the malondialdehyde (MDA) levels. This improvement was accompanied by a concurrent increase in fertility rates, including farrowing rate and litter size, during the liquid preservation process. Furthermore, ZnO-NPs exhibited an antimicrobial effect, resulting in decreased bacterial growth while preserving boar semen at 16°C for 6 days. These findings suggest that ZnO-NPs could serve as a viable alternative to antibiotics, potentially mitigating antibiotic resistance concerns within the food chain.
ABSTRACT
Environmental stress in the form of high temperature humidity index (THI) in tropical and sub-tropical region negatively affects semen quality and fertility of boar. Therefore, the present study was done to evaluate the effect of supplementing flaxseed oil (FLO) to boar's diet on its semen quality, antioxidant status, fatty acid composition of seminal plasma and fertility under sub-tropical climate. For this purpose, six Hampshire crossbreed (50% Hampshire and 50% Gunghroo) boars were divided into two groups i.e control (CON) and treatment (FLO). In FLO and CON group, flaxseed and vegetable oil, respectively, was top dressed at the rate of 3% in basal diets for each boar on daily basis for 16 weeks during monsoon season. A total of 60 ejaculates, comprising 30 ejaculates from each group (ten ejaculates from each boar) were collected. Semen samples were evaluated for sperm quality parameters (SQPs: motility, viability, abnormality, acrosomal integrity and Hypo-osmotic swelling test) and velocity attributes by computer assisted semen analysis (CASA) at fresh and after 72 h of preservation at 17 °C. Antioxidant (glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC and malondialdehyde; MDA) were analyzed in seminal plasma and serum. Fatty acid compositions of seminal plasma were analyzed by gas chromatography-mass spectrometry (GC-MS). In-vivo fertility study was also conducted. Reaction time and false mounts were significantly (p < 0.05) reduced in FLO group as compared to CON group. Semen quality parameters were significantly (p < 0.05) improved at fresh stage and after 72 h of liquid storage in FLO group as compared to CON group. Velocity attributes (VAP, VSL, VCL, ALH, BCF and LIN) were significantly (p < 0.05) higher in FLO group. Flaxseed oil supplementation significantly (p < 0.01) enhanced serum GPx and CAT concentration. Serum and seminal plasma MDA concentration decreased significantly (p < 0.01) in FLO group. Similarly, GPx, TAC and CAT were significantly (p < 0.01) elevated in seminal plasma of FLO group. The study revealed that feeding of flaxseed oil altered the fatty acid composition of seminal plasma and significantly (p < 0.05) improved the farrowing rate. In summary, flaxseed oil supplementation improved the semen quality parameters and fertility of boars in sub-tropical climate by improving the antioxidant capacity and altering the fatty acid composition of seminal plasma.