Abstract:To investigate the cytogenetic parameters and characterise the chromosomal banding pattern of Tho-Tho cattle, a breed of indigenous cattle found in the Northeastern states of India were reared for meat purpose. Lymphocyte culture technique was carried out in 28 Tho-Tho cattle and culture was harvested for good metaphase spread. Good metaphase spreads were selected for analysis, such as relative length, centromeric index and arm ratio. Centromeric banding (C-banding) and reverse banding (R-banding) methods were done for detail and better understanding of the chromosome morphology. The chromosome number in Tho-Tho cattle was observed to be 2n = 60 in all complete metaphase. The mean relative length of the autosomal chromosomes varied from 5.48% ± 0.107% to 1.79% ± 0.105% in male and 5.31% ± 0.148% to 1.86% ± 0.055% in female, respectively. The chromosome banding showed C-positive dark band heterochromatin in all the acrocentric autosome. However, in sex chromosome, the Y-chromosome showed negative C-band and also the X-chromosome did not show any stain at the centromeric region. The numbers of R-band pattern were observed to be 490 and 499 band in male and female, respectively. One of the X-chromosome showed light banding pattern, confirming the inactivation during the embryonic development in female. The fundamental chromosome number and banding pattern of Tho-Tho cattle did not vary from the other breed of the Bos indicus. However, it is necessary to start a cytogenetic screening of the Tho-Tho cattle and expand upon more number to be kept at different villages of Nagaland in order to identify animals with chromosomal abnormalities, so that it can be excluded from future breeding strategies for conservation of Tho-Tho genetic resource.

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