Cryopreservation of Nili-Ravi buffalo bull semen: yearly postthaw analyses to depict climatic effects

The present study was aimed to observe the postthaw quality of Nili-Ravi buffalo bull semen cryopreserved during heat stress (hot summer months) and normal climatic conditions (fall, winter, and spring months). For this purpose, four (n = 4) adult regular donor Nili-Ravi buffalo bulls were selected to collect and cryopreserve their semen throughout the period of an entire year. The cryopreservation of semen was done following standard freezing protocol. The semen doses cryopreserved during heat stress and normal climatic condition were thawed to determine the sperm motility, motion kinetics, viability, plasma membrane integrity, acrosomal integrity, and morphological abnormalities (head, mid-piece, and tail). The results showed that sperm motility and sperm motion kinetics did not alter (p > 0.05) across heat stress and normal climatic period. The sperm head, mid-piece and tail abnormalities did not differ (p > 0.05); however, total sperm morphologic abnormalities were higher (p < 0.05) during heat stress period, whereas the lower (p < 0.05) sperm viability, sperm plasma membrane, and acrosomal integrity were observed during heat stress period. In conclusion, the total morphologic abnormalities, viability, and acrosomal and plasma membrane integrity of buffalo bull sperm cryopreserved during hot summer months are compromised due to heat stress.