Motility and fertilizing capacity of boar semen stored in raffia palm (Raffia hookeri) sap extender at 15°C
Two separate experiments were conducted to test the ability of new semen extenders containing various levels of tropical raffia palm sap in sustaining the motility and fertilizing capacity of boar spermatozoa during storage at 15°C. Highly significant variations (P < 0.01) occurred in the ability of extenders to sustain progressive motility from days 1 to 4 of storage. One of the new extenders, raffia palm extender 2 (RPE–2) was superior to other trial extenders including the control (coconut milk extender, CME) in sustaining progressive motility of boar sperm from 24 - 72 h of storage; average motility scores at 24 and 72 h were 73.0 and 50.0% for RPE-2, 65.0 and 41.0% for CME (control), 55.0 and 36.0% for RPE-1 and 45.0 and 6.5% for RPE-0. Sperm tail vibratory movement was observed in sperm stored in RPE-1 and RPE-0 from day 2 of storage. Sperm in RPE-0 and RPE-1 lost motility completely at 96 h while motility of sperm in RPE-2 showed a sharp drop in motility values from 72 – 96 h relative to control. Average conception rates in 24 gilts inseminated per treatment with semen stored for 24, 48 and 72 h respectively were 83.3, 66.6 and 16.6% for RPE-2, 50, 16.6 and 0.0 percent for RPE-1, 16.6, 0.0 and 0.0% for RPE-0 and 75.0, 50.0 and 26.6% for CME (control). Average number of piglets born using semen stored for 24, 48 and 72 h respectively were 8.0, 8.0 and 6.5 for RPE-2 and 8.2, 8.2 and 6.0 for the control. RPE-2 supported better fetal survival rate than other trial extenders and control. Highly significant variations (P < 0.01) occurred among extenders in conception rate and number of piglets born. These results portray RPE-2 as a reliable short-term liquid semen storage medium for swine artificial insemination in the humid tropics.