Vol. 9(38), pp. 2894-2900, 18 September, 2014 DOI: 10.5897/AJAR2014.8809 Article Number: 2ED941147402 ISSN 1991-637X Copyright © 2014 Author(s) retain the copyright of this article http://www.academicjournals.org/AJAR
African Journal of Agricultural Research
Full Length Research Paper
Chromosomal characteristics of Tho-Tho cattle (Bos indicus) in Nagaland, India Hitu Choudhury*, Vibhuti Bhusan Sarmah, Arindam Dhali, Mitali Dutta Choudhury, Vijay Kumar Vidyarthi, Subodh Kumar, Uttam Kumar Baruah and Dilip Kumar Sarma Krishi Vigyan Kendra Goalpara, National Research Centre on Pig, Indian Council of Agricultural Research, Dudhnoi – 783124, Assam, India. Received 26 April, 2014; Accepted 4 August, 2014
Tho-Tho cattle is a semi-wild indigenous cattle available in Nagaland, India. Tho-Tho cattle has been associated with tribal culture of 16 tribes of Nagaland besides its use for meat, milk and draught purposes. A cytogenetic analysis was conducted in a total of 10 numbers of Tho-Tho cattle (5 males and 5 females) from 3 districts of Nagaland hills situated at mean sea level (msl) ranging from 1000 to 10000 ft (4 nos. from one district and 3 nos. each from other 2 districts). The statistical design included 5 males and 5 females Tho-Tho cattle for gathering data on cytogenetic parameters viz. (i) karyotype, (ii) relative length, centromeric index and arm ratio of chromosome and (iii) construction of ideograms. Statistical tools used for analysis of variation of relative length of each autosome, centromeric index; arm ratio of the ‘X’ chromosome between male and female are done by using the Student’s t-test. Duncan's multiple range test (DMRT) was used to isolate means if the effect was found significant. The study revealed that- (i) Tho-Tho cattle has 29 pairs of autosomes (ii) out of 29 pairs, 23 pairs of autosomes did not differ significantly (P > 0.05) between male and female Tho-Tho cattle in terms of relative length (iii) autosomes are acrocentric, (iv) relative length of 4th, 5th, 6th, 7th and 9th autosomes are significantly (P < 0.05) higher in male; however, 19th autosome of female is significantly (P < 0.05) higher than male (v) X-chromosome in both the sexes is clearly distinguishable and is submetacentric (vi) Y-chromosome (to the total haploid genome) of male Tho-Tho cattle is 1.77 ± 0.10% and it is acrocentric (vii) centromeric index of “X” chromosome in male is 33.75% and in female 32.76% and (viii) Arm ratio of “X” chromosome is found to be 0.66 in male and 0.67 in female. Key words: Centromeric index, Y-chromosome, X-chromosome, sexes, Tho-Tho cattle.
INTRODUCTION Tho-Tho cattle is a local name of a semi wild indigenous cattle, which is found in Sub Himalayan region of North Eastern India, particularly in Nagaland hills at an altitude of 1000 to 10000 ft. msl. No literature is available on ThoTho cattle as no research has been done yet on this animal. Tho-Tho cattle are popular by different names for
different tribes within their own dialects. This cattle is medium in structure (average length in male is 108.2 ± 1.5 cm and in female 106.8 ± 1.7 cm and average height in male is 120.4 ± 1.6 cm and in female 109.8±1.5 cm) and closely associated with tribal rituals, religious and socio economic activities of Naga tribes. This animal is
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Choudhury et al.
CI
40
AR
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0.75
35 0.60
25
0.45
AR
CI (%)
30
20 0.30
15 10
0.15
5 0
0.00 Male
Female
Male
Female
Figure 1. Variation (mean±SE) in centromeric index (CI, %) and arm ratio (AR) of X chromosome in male and female Tho-Tho cattle.
mainly used for meat purpose and also for dairy and tilling and draught purposes. Currently, meagre scientific information is available on the qualitative and quantitative traits of this animal. The animal did not have attract due attention from the appropriate authority due to its remote habitat and semi wild behaviour. Therefore, this study was designed with an objective of investigating chromosomal characteristics to explore its potential as domestic cattle. Investigation on chromosomal profile in livestock provides a useful tool to identify and judge the fertility status of the animal even at an early age (Basumatary, 2003). The knowledge of chromosomal characteristics of Tho-Tho cattle and their effects on economic traits will also be helpful in planning animal breeding strategies.
80i) and digital copy of the image. The homologous pairs of chromosomes were identified by matching their absolute length. The chromosome pairs were then arranged in a decreasing order of length and a digital image of the full set was prepared using the Adobe photoshop software.
Estimation of relative length, centromeric index and arm ratio of the chromosomes Length of chromosomes was measured from centromere to telomere in case of acrocentric chromosomes and tip of short arm to the tip of long arm in case of submetacentric chromosomes. Length of the homologous chromosomes; X-chromosome in female and in case of males, lengths of “X” and “Y” were measured separately and calculated using the formula (Mean±SE) described by Choudhury et al. (1997). The centromeric index of the submetacentric chromosomes was calculated using the formula (Choudhury et al., 1997).
METHODOLOGY Construction of idiograms A cytogenetic analysis was conducted in a total of 10 Tho-Tho cattle (5 males and 5 females) from 3 districts of Nagaland hills situated at mean sea level (msl) ranging from 1000 to 10000 ft (4 from one district and 3 each from other 2 districts). Based on the secondary data on habitat of Tho-Tho cattle collected from Department of Animal Husbandry and Veterinary, Forest and environment, National Research Centre on Mithun and village heads; Kohima, Phek and Zunheboto districts of Nagaland were selected for the survey. Sample size was purposefully fixed at 5 males and 5 females. Cytogenetic parameters studied were (i) karyotype, (ii) relative length, centromeric index and arm ratio and (iii) construction of ideogram. For karyotype study a total of 100 karyotypes (50 from 5 males 50 from 5 females) were prepared to study the morphometry of chromosomes following the protocol described by Moses (1974).
Karyotype preparation The chromosomes were counted and numbered on the printed copy of the image. Length of each chromosome was determined using the image analysis software of the Nikon microscope (Eclipse
A total of 30 karyotypes from 5 males and 5 females were taken for preparation of idiograms (Figures 2 and 3) as described by Rowley (1974). Statistical tools used were for analysis of variation of relative length of each autosome, centromeric index; arm ratio of the ‘X’ chromosome between male and female are done by using the Student’s t-test. Duncan's multiple range test (DMRT) was used to isolate means if the effect was found significant.
RESULTS Ecological and environmental conditions are presented in Table 1. The results of the cytogenetic characters are presented in Table 2. The cytogenetic analysis of ThoTho cattle revealed a diploid number of 60 XX in female and 60 XY in male. The morphometric measurements obtained from each pair of chromosomes and sex chromosomes were expressed in terms of relative length
Afr. J. Agric. Res.
Mean relative length (%)
6 5 4 3 2 1 0 1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 X Y Chromosome number
Figure 2. Idiogram of male Tho-Tho cattle.
6
5 Mean relative length (%)
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4
3
2 1
0 1 2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 X Chromosome number
Figure 3. Idiogram of female Tho-Tho cattle.
Table 1. Month wise variation in average temperature, dew point, relative humidity and rainfall in different districts.
Particulars Kohima District Average temperature (°C) Average Dew Point (°C) Average relative humidity (%) Average rainfall (mm)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
10.2 6.8 61.1 15.2
12.2 7.7 60.1 10.5
16.1 12.4 58.6 34.5
19.3 12.8 63.1 162.1
20.6 14.9 74.3 148.2
21.6 16.7 80.5 238.3
22.4 18.5 82.9 377.4
22.1 19.8 82.8 290.4
21.2 19.7 82.4 232.4
18.9 18.3 77.4 70.4
15.4 15.7 71.8 22.3
11.7 12.5 62.7 20.7
Phek District Average temperature (°C) Average Dew Point (°C) Average relative humidity (%) Average rainfall (mm)
11.5 5.6 71.1 16.6
13.9 8.4 47.8 10.1
17.1 9.6 64.2 30.1
17.6 12.8 74.3 178.3
20.1 13.7 75.5 190.5
21.8 16.8 80.8 193.9
22.2 18.3 85.2 344.5
22.7 19.1 82.9 296.1
21.7 18.2 84.7 180.6
19.1 16.4 82.5 172.1
15.5 13.6 83.3 26.6
12.2 10.5 78.2 21.7
Zunheboto District Average temperature (°C) Average Dew Point (°C) Average relative humidity (%) Average rainfall (mm)
9.7 4.1 88.2 33.5
11.5 6.5 85.1 18
13.4 10.2 88.2 46
14.2 9.8 85.8 279.6
15.2 10.1 87.7 298.3
18.2 12.7 89.9 318.3
19.2 14.7 92.9 410.8
19.2 16.6 95.3 443.2
18.4 17.1 90.8 299.7
17.9 15.7 89.9 133.6
15.8 12.6 84.8 41.3
13.7 9.3 58.3 1.3
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Table 2. Relative length (mean ±SE) of the chromosomes (haploid set) of Tho-Tho cattle.
Chromosome pair no. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 X Y a,b
Relative length (%) Male (Mean ± SE) Female (Mean ± SE) 5.19 ± 0.12 5.38 ± 0.16 4.83 ± 0.05 4.81 ± 0.08 4.63 ± 0.05 4.49 ± 0.03 4.53 ± 0.04a 4.34 ± 0.04b 4.42 ± 0.06a 4.22 ± 0.05b a 4.31 ± 0.05 4.09 ± 0.04b a 3.97 ± 0.05b 4.14 ± 0.02 4.00 ± 0.03 3.88 ± 0.04 3.85 ± 0.03a 3.75 ± 0.02b 3.73 ± 0.02 3.62 ± 0.05 3.61 ± 0.02 3.55 ± 0.05 3.46 ± 0.07 3.43 ± 0.06 3.34 ± 0.06 3.31 ± 0.03 3.17 ± 0.03 3.24 ± 0.05 3.05 ± 0.03 3.16 ± 0.05 2.96 ± 0.02 3.07 ± 0.07 2.88 ± 0.04 2.99 ± 0.04 2.80 ± 0.05 2.91 ± 0.03 2.67 ± 0.03a 2.81 ± 0.04b 2.61 ± 0.04 2.73 ± 0.03 2.51 ± 0.06 2.65 ± 0.04 2.44 ± 0.04 2.55 ± 0.04 2.39 ± 0.05 2.49 ± 0.05 2.33 ± 0.03 2.43 ± 0.05 2.26 ± 0.02 2.33 ± 0.06 2.15 ± 0.01 2.25 ± 0.06 2.10 ± 0.02 2.18 ± 0.05 2.04 ± 0.02 2.10 ± 0.04 1.93 ± 0.05 1.88 ± 0.10 5.70 ± 0.10 5.45 ± 0.09 1.77 ± 0.10 -
Indicates values within row differ significantly (P
