Infertility associated with monosomy-X in a crossbred cattle heifer
Prakash, B.; Balain, D.S.; Lathwal, S.S.; Malik, R.K.
Veterinary Record 137(17): 436-437
1995
ISSN/ISBN: 0042-4900 PMID: 8560704 Document Number: 446532
A healthy, 6-year-old Holstein (Bos taurus) cross local (B. indicus) heifer which showed regular oestrus but had failed to conceive despite repeated breeding was examined and found to have phenotypically normal external genitalia. Rectal examination identified normal sized but flat ovaries with adhesions and a bend in the cervix. Cytogenic analysis of blood cultures showed that 98 of 100 metaphases analysed had 59 chromosomes and 2 had 58 chromosomes with only one X chromosome. The normal karyotype of B. taurus and B. indicus female cattle consists of 60 chromosomes. The missing chromosome was one of the 2 X chromosomes, so its karyotype conformed to the 59, XO complement. In addition one homologue of the smallest autosome pair was significantly smaller than its partner, it also stained more heavily than other chromosomes and maintained its shortened shape even in pre-metaphase cells. It is suggested that monosomy-X syndrome, which affects viability in man, may also be a major cause of fetal losses in livestock. Further cytogenetic studies are needed to improve the understanding of the incidence and cause of various chromosomal anomalies in livestock.