Incidence of ‘Dag’ like defect and its implication on qualitative attributes of semen in Crossbred Frieswal Bulls

Abstract

The study was conducted on 123 Frieswal bulls, aged 2 - 6 years. Frieswal bulls are crosses between Holstein Friesian [Bos taurus] X Sahiwal [Bos indicus]; having 5/8 Holstein Friesian and 3/8 Sahiwal inheritance. The objective of the study was to find out degree of occurrence of ‘Dag’ like defect in ejaculates of Frieswal crossbred bulls and its implications on other qualitative attributes of semen and its cryo-preservability. Bulls were classified into 4 categories i.e. category 1- up to 1% ‘Dag’ like defect , category 2- 1.1 to 2.0%, category 3- 2.1 to 4.0 %, and category 4- more than 4.0 % ‘Dag’ like defect. Present study showed 42 of 123 bulls (34.15%) had average ‘Dag’ like defects up to 1%, 37 bulls (30.08 %) had 1.1-2.0% defects, 31 bulls (25.20%) had 2.1-4% defects and rest 13 bulls (10.57%) had more than 4% ‘Dag’ like defects. Sperm concentration, progressive motility, plasmallemal integrity and live sperm per cent were significantly higher in category 1 bulls as compared to other categories. Total abnormal sperm, major and minor sperm defects were significantly lower in category 1 bulls as compared to others. Abnormal sperm per cent in category 1 bulls was 16.38±0.82 %, where as in categories 2, 3 & 4 it was 1.7, 2.7 & 3.3 times higher, respectively. It was concluded that presence of very strongly coiled and folded tail with or without split of tail fibre (‘Dag’ like defects) up to 2% level is quite obvious in normal ejaculates. As the level of this defect increases, the spermiogram and qualitative attributes of semen showed deterioration. The cryo-preservability of semen was satisfactory with ejaculates of bulls having up to 2% of ‘Dag’ like defects and above 4% levels semen quality and their cryo-preservability was extremely poor. Bulls between 2.1- 4% sperm defect had intermediate semen quality and showed inconsistent freezability.  Thus, monitoring of the incidence of ‘Dag’ like defect (very strongly coiled and folded tail with or without split of tail fibre) in sperm would provide better indication of spermiogram and functional attribute of testes in crossbred Frieswal bulls.