Comparisons of commercial Triladyl and locally manufactured extenders for the chilling of semen and their effects on pregnancy rates after transcervical AI in Bangladeshi Indigenous (Ovis aries) sheep

Two different extenders were compared for their effects on preservation of semen from Indigenous rams and on pregnancy rate (PR) in Indigenous ewes. Semen was collected from nine Indigenous rams (Ovis aries) once a week using an artificial vagina. Each ejaculate was divided into 2 aliquots, diluted with either commercial (Triladyl (R)) or locally manufactured (tris, fructose, citric acid, egg yolk: TFE, prepared in own laboratory) extenders and kept at 4 degrees C for 48 h. Motility, viability, functional integrity and morphological changes were evaluated at 0, 24 and 48 h. Synchronized oestrus ewes inseminated transcervically with 24 and 48 h of preserved chilled semen diluted with Triladyl and TFE extenders separately. Semen preserved in Triladyl had better motility, viability, and functional integrity at 24 and 48 h (P < 0.001) than did in TFE. The morphologically normal spermatozoa up to 48 h of preservation did not differ between extenders. However, in abnormalities studied, Triladyl had detrimental effect on sperm acrosome and TFE on sperm tail (P < 0.001) at 24 and 48 h of preservation. But, midpiece was not affected by any extender (P > 0.05) over the entire period of preservation. The quality of semen decreased (P < 0.001) with increasing preservation time for both extenders. The extenders did not differ (P > 0.05) the overall PR after transcervical AI (TCAI) in ewes. Increased preservation time (48 h) negatively affected the PR in TFE extended semen compared with than that of Triladyl. The results suggest that the quality of chilled semen (motility, viability, and functional integrity) is more improved when preserved in Triladyl than if extended with a TFE. PR may higher when TCAI is performed with chilled semen preserved in Triladyl for a longer time than TFE. However, TFE extender may be used to dilute the semen for chilling and used in TCAI to get similar PR of Triladyl up to 24 h of preservation.