Variations in the Length of the Y Chromosome and the Seminal Attributes of Karan Fries Bulls A. Mandal 1 * and A. Sharma 2 1 Genetics and Breeding Division, Central Institute for Research on Goats, Makhdoom, Farah, Mathura 281 122, U.P., India; 2 Genetics Division, Indian Veterinary Research Institute, Bareilly, Izatnagar, U.P., India *Correspondence: E-mail: ajoy@cirg.up.nic.in Mandal, A. and Sharma, A., 2003. Variations in the length of the Y chromosome and the seminal attributes of Karan Fries bulls. Veterinary Research Communications, 27(7), 567^575 ABSTRACT Fresh semen and blood samples from 20 Karan Fries bulls (4^6 years of age), maintained at the Arti¢cial Breeding Complex of the National Dairy Research Institute, Karnal, were collected for one year. All the bulls had 60 chromosomes, comprising 58 acrocentric autosomes and 2 sex chromosomes, with X as the larger and Y as the smaller submetacentric. The mean lengths of Y p and Y q ; the total length of the Y chromosome and the length ratio were 1.10+0.01 mm, 1.83+0.02 mm, 2.92+0.02 mm and 62.46%+0.18%, respectively. Analysis of the length measurements of the the Y chromosomes in Karan Fries bulls showed that all the measurements, viz., the short arm of the Y chromosome, the long arm of the Y chromosome, the total length of the Y chromosome and the variation in length of Y chromosome, varied signi¢cantly among bulls. All the seminal parameters, the volume of semen, mass activity, initial motility, concentration, live sperm count and the total abnormal sperm count, were signi¢cantly a¡ected by bulls, whereas season had a signi¢cant e¡ect on all the seminal parameters except the total abnormal sperm count. No signi¢cant relationship between the ratio of the long arm to the total length of the Y chromosome and seminal attributes was observed. Keywords: bull, crossbred, length, morphometry, semen, seminal characteristics, Y chromosome Abbreviations: DAZ, deleted in azoospermia; TDF, testis determination factor; Y p , short arm of the Y chromosome; Y q , long arm of the Y chromosome; Y p+q , total length of the Y chromosome INTRODUCTION The mammalian Y chromosome has made a unique contribution to cytogenetics in that its presence usually denotes maleness in the individual possessing it.Variations in the size and shape of the chromosome have been observed, to a greater or a lesser degree, between species in the same genus and between individuals of the same species having the same chromosome number. Most of the variations in the length of the Y chromosome occur due to di¡erences in the long arm of the chromosome, which varies both from individual to individual and from breed to breed in mammals. Signi¢cant variations have been reported in the length of the Y chromosome in di¡erent breeds of cattle (Giovanni and Cribiu, 1977; Halnan and Watson, 1982) and Bos taurus6Bos indicus crosses (Betancourt, 1985). Veterinary Research Communications, 27 (2003) 567^575 # 2003 Kluwer Academic Publishers. Printed in the Netherlands 567