Effect of various extenders and additives on deep-freezing, enzyme leakage and fertility of bovine semen under tropical climate*

Abstract

The relative merits of tris (TFYG), cilrate (EYCG) and lactose (LYG) based diluouts without or with inclmion of cysteine HCI 0.1%, EDTA 0.1% awl raffinose 1.0% were evaluated under split-sample technique for deep-freezing of semen of 3 HF bulls in 18 ejaculates. The mean motile sperm observed on
dilution and at pre- and post-freezing were 81.20±0.35. 75.79±0.37 and 46.92±0.70%. The values after 30,60 and 120 min of post-thaw incubation (37°C) were 34. 70±1.00, 22.04± 1.03 and 11.46±0.84%. The mean glutamic oxaloacetic and glutamic pyruvic transaminase (GOT-GPT) activities in the pre-freeze seminal plasma (60 millon sperm/ml) averaged 19.08±0.39 and 5.87±0.17 pmole/litre, which increased to
the levels of 28.67±D.S5 and 9.90±0.22 pmole/litre in frozen-thawed samples. The mean conception rate obtained with frozen semen Meminations was 59.13%. All these traits were highly significantly influenced by the bulls, extenders, additives and periods. However, the interactions between these factors were not significant for enzyme leakage. Significantly greater sperm motility and lesser GOT-OPT leakage were recorded at all the steps of semen processing in TEYG diluent as compared to EYCG and LYG diluents. Although conception rates did not vary significantly between them. The freezability, post-thaw
thermoresistance and fertility of semen were also enhanced significantly and the enl,yme leakage was reduced with the inclusion of cysteine and/or EDTA in all diluents as compared to control Of even raffinose added diluents. The correlations between pre-/post-freezing sperm motilily and GOT-GPT leakage were significantly negative. Fertility rates showed significant positive correlations with sperm motility and negative correlations with enzyme leakage at various stages. These findings proved the superiority of TFYG diluent and The beneficial role of cysteine and EDTA as additives in improving the post-thaw quality and fertility ofhovine semen, and hence may be recommended for its routine use by all semen hanks in tropics.