Alteration in sperm mitochondrial membrane potential and antioxidant biomarkers in summer adversely affects Hampshire-Ghungroo crossbred boar semen fertility in subtropical climate

MAHAK SINGH ^1* Apanai Celina ¹ Rahul Katiyar ² Sourabh Deori ² Ashwani Singh ³ Vinay Singh ⁴ G D Singh ⁵ J S Rajoriya ⁶ H Kalita ¹ V K Mishra ²

• ¹ ICAR Research Complex for NEH Region, Nagaland Centre, Medziphema, Nagaland, Medziphema, India
• ² The ICAR Research Complex for North Eastern Hill Region (ICAR RC NEH), Umiam, Meghalaya, India
• ³ College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India
• ⁴ Indian Council of Agricultural Research, ICAR Research Complex for NEH Region, Agartala, Tripura, India
• ⁵ Department of Veterinary Clinical Complex Bihar Veterinary College, Patna – 800014 (India), PATNA, India
• ⁶ College of Veterinary Science and Animal Husbandry, Nanaji Deshmukh Veterinary Science University, Jabalpur, Madhya Pradesh, India

Temperate boars are adversely affected by environmental heat stress in sub-tropical climate and their semen quality and fertility is severely compromised as compared to indigenous breeds.Therefore, the present study aimed to evaluate the effect of season on semen quality, antioxidant status and in-vivo fertility of crossbred pigs having exotic (50%) and indigenous inheritance in sub-tropical climate. Fourteen Hampshire-Ghungroo crossbred boars were used in the summer and winter season. Sperm characteristics viz. 'motility, viability, abnormality, acrosomal integrity, Hypo-osmotic swelling test (HOST)'and mitochondrial membrane potential (MMP) were evaluated. Sperm velocity attributes were assessed by computer-assisted semen analysis (CASA). Antioxidant biomarkers ('glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC') and lipid peroxidation (malondialdehyde; MDA) were analysed in boar's seminal plasma. Summer season had significant (p < 0.01) negative effect on reaction time and false mounts. Semen volume and sperm concentration were significantly (p < 0.01) higher in winter season. Sperm abnormalities were significantly (p < 0.01) lower in the winter season.Sperm quality parameters (SQPs) like 'total motility, progressive motility, viability, acrosomal integrity and HOST reactive sperm' were significantly (p < 0.01) improved in the winter season.Sperm MMP was significantly (p < 0.01) lower in summer at fresh as well as at 72 hrs of storage. There was a significant (p < 0.05) effect of season on the 'velocity attributes viz. VAP, VSL, VCL, ALH and BCF'. Semen characteristics after 72 hours of cold storage were significantly (p < 0.01) higher in winter as compared to summer season. Seminal plasma antioxidant biomarkers (TAC, MDA, CAT and GPx) were significantly (p < 0.01) affected by the summer season. Farrowing rate was significantly (p<0.05) higher in the winter season. In conclusion, we found that low boar sperm's MMP and down regulation of seminal plasma antioxidant biomarkers in summer causes poor semen quality and fertility of Hampshire-4 Ghungroo crossbred boar in a sub-tropical climate. To alleviate the heat stress induced poor sperm fertility in boar, there is need for scientific intervention in terms of genetic (less exotic inheritance (below 50%)), nutrition and management to optimize the boar fertility during summer months in sub-tropics.