Master's Thesis from the year 2015 in the subject Biology - Zoology, , language: English, abstract: In the present study semen samples from NRF bulls were analysed for sperm viability, acrosome integrity and ATP content. The effect of incubation at 37 °C on sperm viability, acrosome integrity and ATP content was investigated on fresh and frozen semen samples from 20 NRF. Semen was incubated at 37 °C and the sperm quality parameters were analysed at 0 hr and after 6 and 24 hrs of incubation for both fresh and frozen samples. Sperm viability and acrosome integrity was assessed with flow cytometry and ATP content with luminometer. The incubation time at 37 °C had a significant effect on all studied parameters. However, ATP content was significantly more affected than sperm viability and acrosome integrity. After 24 hrs of incubation ATP content of frozen samples decreased approximately to 0 for all tested samples, while percentage of viability and acrosome integrity decreased by 78 ± 11.9 %. Percentage of AIL sperm cells of frozen samples decreased at corresponding rate as in fresh samples. Concerning ATP content there was however, a more marked decline in frozen samples compared to fresh samples during incubation. Sperm samples from eight NRF bulls with high and low fertility were also analysed for sperm viability, acrosome integrity and ATP content at 0 hr (right after thawing), 3, 6 and 24 hrs incubation at 37 °C. The ATP content adjusted for % AIL at 0 hr was significantly correlated with fertility measured as 56 days NRR, while % AIL or ATP content analysed separately were not correlated to field fertility.