Cytogenetic Screening of Karan Fries and Tharparkar Males for Selection of Elites at an Early Age

Abstract

The importance of sire selection in the herd is reflected in the total genetic gain through sire-to-sire path and sire-to-dam path being more than 50 percent contribution. The present investigation was envisaged with the objective of screening chromosomes with conventional cytogenetic techniques in males of Tharparkar and Karan-Fries cattle and to find association between chromosomal anomalies and performance of males. 25 and 15 males of KF (Karan Fries) and TP (Tharparkar) respectively were utilized for cytogenetic and semen evaluation work at ICAR-National Dairy Research Institute, Karnal. Cytogenetic screening of animals could not show gross numerical and chromosomal aberrations, while fragile sites were revealed by induction with aphidicolin. The average percentage of fragile sites in autosomes and sex chromosomes were found 14.66 and 6.16 respectively in KF males, while in TP males average percentages were 7.66 and 4.9, respectively. Association study revealed that fragility in autosomal chromosomes had significant effect on the birth weights in KF males and no association was found between any libido and reproductive trait with the percent fragile sites either in autosomes or sex chromosomes. Cytogenetic screening is recommended at the initial stage for the propagation of only elite bull semen used for A.I. Association between autosomal fragility and birth weights although found highly significant but still need to be validated with large sample size.