الفهرس 
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Abstract
Fertility is one of the most important performance to domestic animals and it is very sensitive to the disturbance in the chromosomes chromosome aberrations in cattle, receiving an increased amount of attention, where the play an important role in lowering the fertility or even sterility
The present work was undertaken to detennine the chromosomal aberrations of some animals showing some reproductive problems.
The material of this work included 54 friesian heifers and 16 bulls raised in Egypt. These animals were grouped according to the type of reproductive problems into five groups, one group of normal pregnant heifers served as control female group and other normal breeding bulls used as a control male group. Blood samples were collected from the animals.
Whole blood cultures were set up and cluomosomal preparations made, karyotypes were prepared using standard Giemsa stain. In every animal, 50 metaphase were examined for structural and numerical aberrations.
’Repeat breeders group :
This group consisted of 25 repeat breeders heifers. Among 1250 metaphases examined 462 metaphases were aberrated, the chromosomal analysis revealed that : polyploidy cells (3.68%) and perdiploidy cells
(8.16%) as numerical aberrations (11.84%). Chromatid gaps (11.764%), chromatid break (4.96%), chromosome gaps (3.36%), chromosome breaks (3. I 2%) and centric fusion (2.48%) as structural aberrations (25.68%). the total chromosomal aberrations were 37.52%.
•Control female group :
This group consisted of 25 pregnant heifers. Among 1250 metaphases examined, 125 metaphases were aberrated, the chromosomal analysis revealed that : polyploidy cells (2.64%) and peridiploidy cells (5.04%) as numerical aberrations, Chromatid gaps (1.68%), chromatid break (1.04%), chromosome gaps (0.0%), chromosome breaks (0.4%) and centric fusion (0.72%) as structural aberration (3.84%). The total chromosomal aberrations were 11.52%).
•Freemartin group’:
This group consisted of 4 animals, one of them has no uterus or ovaries. Among 200 metaphases examined 45.5% was XX sex chromosome complement, 46.5% was XY sex chromosome complement 6.5% was XY sex chromosome complement 1% was X0 and 0.5 was OY also, cytogenetical examination revealed chromosomal aberrations in this group as following :
Peridiploidy cells (5%) as numerical aberrations. Chromatid gaps (8.5), chromatid breaks (8%), chromosome gap (2%), chromosome break (1 %) and centric fusions (0.5%) as structural aberrations (20%). the total chromosomal aberrations was 25%.
•Affected male group : (unilateral testicular orchidy)
This group consisted of 8 animals with unilateral testicular aplasia. Among 400 metaphases examined 148 metaphases were aberrated. The chromosomal analysis revealed that : polyploidy (3.5%) and peridiploidy (7.5%) as numerical aberrations (11%). Chromatid gaps (11.3%), chromatid break (5.3%), chromosome gaps (3.5%), chromosome break (2.5%) and centric fusions (4.3%) as structural aberrations (26.75%). The total chromosomal was 37.75%.
•Control male group :
This group consisted of 8 breeding bulls used for natural services and A.I. purposes. Among the 400 metaphases examined 57 metaphases were aberrated. The chromosomal analysis revealed that : polyploidy (4.8%), peridipolidy (6.3%) as numerical aberrations. Chromatid gaps (2.5%), chromatid break (2%), chromosome gap (0.0%), chromosome break (0.0%) and centric fusion (0.8%) as structural aberrations (5.3%). The total chromosomal aberrations were 16.3%.