author(s)
Manoj Kumar Kalita, Sudip Sinha, Ranjan Kumar Biswas, Bharat Chandra Deka, Monjyoti Bhuyan, Kutubuddin Ahmed and Girin Hazarika

abstract
We investigated the effect of concentrations of 150, 200 and 300 million sperm /ml containing 37.5, 50 and 75 million sperm respectively in 0.25 ml straws during freezing on post-thaw quality semen pulled from Beetal and Sirohi bucks. The overall mean per cent post-thaw sperm motility, live sperm, intact acrosome and HOST-reacted sperm for straws containing 37.5, 50 and 75 x10⁶ sperm/ straw was 56.02 ± 0.47, 57.50 ± 0.41 and 65.57 ± 0.58;67.42 ± 0.62, 70.55 ± 0.55 and 73.45 ± 0.57; 61.12± 0.69, 64.37± 0.66 and 68.25± 0.66; and 59.00 ± 0.62, 62.77± 0.52 and 65.57 ± 0.58 respectively. The post-thaw values of all semen parameters studied in straws with 75 million sperm were significantly (P<0.01) higher than that of 50 and 37.5 x10⁶ sperm / straw. The post thaw values with 50 x10⁶ sperm/ straw was significantly (P<0.01) higher than that with 37.5 x10⁶ sperm /straw for sperm motility, intact acrosome and HOST-reacted sperm but not for live sperm. The fertility rate recorded using the three different sperm concentrations separately in Beetal and Sirohi goats revealed that it was the highest with 75 x10⁶ sperm /straw in both the breeds. It was revealed from the present study that the post thaw quality and fertility of goat semen for 75 x10⁶ sperm / straw was superior to that for 50 x10⁶ and 37.5 x10⁶ sperm / straw.