




































In ternationa l
Scholars
Journa ls

 

African Journal of Pig Farming ISSN 2375-0731 Vol. 5 (2), pp. 001-006, February, 2017. Available online at 
www.internationalscholarsjournals.org © International Scholars Journals 

 

Author(s) retain the copyright of this article. 

 

Full Length Research Paper 

 

Cytogenetic characterization of Nigerian indigenous pig 
 

Oluwole, O. O.* and Omitogun, O. G. 
 

Department of Animal Science, Obafemi Awolowo University, Ile-Ife, Nigeria. 
 

Accepted 19 October, 2016 
 
This work studied the chromosomal structure of the Nigerian indigenous pig (NIP). The karyotype was obtained and a 
detailed karyogram constructed. Using sixty-two metaphases of the NIP obtained from both mature male and female 
leucocytes culture, the chromosomal structure was studied. The karyotype obtained was based on the chromosome’s 
relative length, centromere position and arm (p/q) ratio. The cells had the usual diploid complement of 38 
chromosomes (2n = 38) and a NOMBRE FONDAMENTAL of 64 as in the exotic. The karyotype of NIP was characterized 
by submetacentric chromosome pairs 1 – 7; metacentric chromosome pairs 8 to 12 and telocentric chromosome pairs 
13 to 18 with submetacentric XX for female and XY for male. A detailed karyogram was constructed from the obtained 
results. 

 

Key words: Karyotype, Nombre fondamental, Nigerian indigenous pig. 

 
INTRODUCTION 

 
The black hairy NIP is known with special traits such as 
greater resistance to African swine fever and heat tole-rance 
of high parasitic load, high percent of weaner weaned and 
low age at puberty (Adebambo,1982). NIP thrive better in 
extreme condition than exotic pig (Ilori, 1974). Due to 
extensive breeding with introduced exotic pig breed, there is 
a risk of loosing the gene pool of these traits (Adebambo, 
2003). From genome analysis point of view (Galman et al., 
1991), pig has the same genome compared to that of human 
(30 morgans or 3 x 10

9
 bp in length). The karyotype of the 

domestic pig composed of 18 pairs of autosome and pairs of 
sex chromosomes (X or Y) are already well characterized of 
which 13 are metacentic and 6 are acrocentric (CSKSS, 
1988;CTA, 1994; Fairbank 1999).  

Much cytogentic work has been done on the exotic pig 
bread but none has been done on the NIP (Omitogun, 
2004). This paper therefore aims at filling this gap by in-
vestigating the characteristics of the NIP at the chromo-
somal level and to compare its karyotype with the already 
published karyotype of the exotic pig. 
 
 
MATERIALS AND METHODS 
 
Animals were purchased from three remote areas of 
South Western  
 
 
 
*Corresponding author. E-mail: oluwafunmike@yahoo.co.uk.  
Tel: +234(0)8053570807. 

 
 
 
 
 

Nigeria; Otan lle (llesa), lwo and lle-lfe and maintained at the 
Teaching and Research Farm of Obafemi Awolowo University. 
Blood was collected from the jugular veins using 18-gauge syringes 
and immediately transferred into heparinized bottles. The blood (0.7 
ml) was cultured for 72 h in 10 ml of RPMI 1640 (SIGMA) supple-
mented with 0.1 ml of phytohaemaglutinin (SIGMA) and 10% fetal 
Bovine Serum (G1BCO). 1 h before harvesting, colchicine 0.8 µg/ml 
was added to arrest the cells at metaphase stage. After centrifu-
gation at 1000 rpm for 10 min, the blood lymphocyte layer was 
collected and transferred into clean dry test-tubes.  

5-10 ml of 0.075% of hypotonic solution was added, re-
centrifuged and fixed three times with cold 3:1 methanol and glacial 

acetic acid (v/v) fixative. The fixed cells were stored at 4
0
C for 3 to 

4 days. Chromosome suspensions were dropped on a pre-cleaned 
microscope slides, then stained. Stained and well-spread meta-
phase were analysed under the microscope, then photographed 
and karyotyped. Out of the 62 metaphasic chromosome photo-
graphs, 10 photographs with well-spread chromosome from 5 male 
and 5 female pigs were selected for karyotyping. From these 10 
karyotypes of the NIP, means of each of 18 chromosomal arm 
lengths were obtained using a compass and a ruler to obtain the 
arm length ratios, centrometric indices and total chromosomal 
length which were required for classification of the chromosome 
(Abraham and Prasad, 1983). The karyogram showing size, varia-
tion and morphology of the chromosome were plotted using Micro-
soft Excel. 

 

RESULTS AND DISCUSSION 
 

The karyotypic data obtained from the analysis of each 
chromosome of the Nigerian Indigenous Pig (NIP) and 
Exotic pigs are shown in Table 1 and 2. These showed the 
cytogenetic analysis of the 18 pairs of chromosome of the 
NIP and exotic pigs. The short and long arm lengths 



  
 
 

 
Table 1. The cytogenetic analysis of the 18 pairs of chromosome of the Nigerian Indigenous Pig (NIP). 

 

Chromosome P (± sd) q (± sd) p + q  (± sd) TCL Arm ratio C.I C.T 

pair No. (µm) (µm) (µm) (%) p/q 100p/(p + q)  

1 0.72 (± 0.15) 1.67 (± 0.15) 2.39 (± 0.53) 9.32 0.43 30.13 nsm (-) 

2 0.50 (± 0.19) 0.95 (± 0.18) 1.45 (± 0.37) 5.65 0.53 34.48 nsm (-) 

3 0.45 (± 0.09) 0.96 (± 0.21) 1.41 (± 0.30) 5.50 0.47 31.91 nsm (-) 

4 0.45 (± 0.13) 0.92 (± 0.19) 1.37 (± 0.32) 5.34 0.49 32.85 nsm (-) 

5 0.34 (± 0.05) 0.80 (± 0.14) 1.14 (± 0.19) 4.45 0.43 29.82 nsm (-) 

6 0.39 (± 0.24) 1.29 (± 0.38) 1.68 (± 0.62) 6.55 0.30 23.21 nsm (-) 

7 0.36 (± 0.07) 0.75 (± 0.12) 1.11 (± 0.19) 4.33 0.48 32.43 nsm (-) 

8 0.59 (± 0.11) 0.72 (± 0.11) 1.31 (± 0.22) 5.11 0.82 45.04 nm 

9 0.45 (± 0.08) 0.56 (± 0.11) 1.01 (± 0.19) 3.94 0.80 44.94 nm 

10 0.43 (± 0.18) 0.59 (± 0.10) 1.02 (± 0.28) 3.98 0.73 42.15 nm 

11 0.37 (± 0.10) 0.46 (± 0.12) 0.83 (± 0.22) 3.24 0.80 44.58 nm 

12 0.36 (± 0.07) 0.38 (± 0.12) 0.74 (± 0.19) 2.89 0.95 48.65 nm 

13 0 2.1 (± 0.19) 2.1 (± 0.19) 8.19 0 0 T 

14 0 1.69 (± 0.28) 1.69 (± 0.28) 6.59 0 0 T 

15 0 1.47 (± 0.22) 1.47 (± 0.22) 5.73 0 0 T 

16 0 0.93 (± 0.25) 0.93 (± 0.25) 3.63 0 0 T 

17 0 0.79 (± 0.14) 0.79 (± 0.14) 3.08 0 0 T 

18 0 0.71 (± 0.14) 0.71 (± 0.14) 2.77 0 0 T 

X 0.35 (± 0.15) 1.38 (± 0.26) 1.73 (± 0.41) 6.75 0.25 20.23 nsm (+) 

Y 0.38 (± 0.13) 0.38 (± 0.16) 0.76 (± 0.29) 2.96 1.0 50 m 
 

CT = Chromosome type (Abraham and Prasad, 1983); TCL = total chromosome length percentage [(p + q)/Σ(p + q)] x 100; CI = 
centromere index = (p/p + q) x 100; p = short arm length; q = Long arm length; p + q = total chromosome length; nsm = nearly 
submetacentric; nm = nearly metacentric; m = metacentric; T = telocentric. 

 

 

are presented as well as the Centromere index, the total 
chromosome lengths in percentage and the chromosome 
type.  

Figure 1 and 2 showed the solid stained metaphasic 
chromosomes of the male Nigerian indigenous pig and its 
karyotype. The Figure showed the unbanded karyotype of 
NIP having 38 chromosomes comprising of 19 pairs of 
autosomes, a large X and a very small Y sex 
chromosomes. The karyogram of NIP showing the 
morphology of the chromosomes is presented in Figure 2 
while the karyogram with size variation among 
chromosomes is presented in Figure 3. 
 

 

Chromosome number and nombre fondamental 

 

The result obtained (Figures 1 and 2) showed that the 
NIP has a chromosome number of 2n = 38 and nombre 
fundamental (NF) of 64, which are the same with those of 
the exotic Sus scrofa domestica (CSKSS, 1988). Nombre 
Fondamental was coined by Mathey (1945) as an index 
for quick estimation of the nature of the chromosome in a 
karyotype in relation to the presence or absence of arms. 
This NF value of 64 showed that 6 diploid chromosomes 
are telocentric, that is, chromosomes 13 – 18. The agree-
ment of the NF value of the NIP with that of the exotic pig 
indicates high degree of resemblance between the two. It 

 
 

 

is however believed that diversity in NF indicated species 
at different evolutionary levels with the more advanced 
ones showing an increase in metacentric chromosome at 
the expense of the telocentric ones (Dallai and Telluri, 
1969) but this study does not show that. 
 
 
Chromosome morphology 

 
The morphology of the NIP chromosomes observed could 
be divided into three main groups according to their 
structures and sizes: 

 
Group I: The chromosomes under this group are chromo-
somes 1-7 including the X sex chromosomes. They are 
submetacentric and distinct by identifiable in all meta-
phase spreads.  
Group II: This group consists of chromosomes 8-12 and 
Y sex chromosome. They are metacentric chromosomes. 
Group III: These consist of chromosomes 13-18 and are 
telocentric. 
 

Each chromosome description is as follows: 
 
 
Group I 
 
Chromosome  1:  This is the longest  submetacentric 



 
 
 

 
Table 2. The cytogenetic analysis of the 18 pairs of chromosome of the  Exotic pigs. 

 

Chromosome P q p + q TCL (%) Arm C.I C.T 

pair No. (µm) (µm) (µm)  ratio p/q 100p/(p + q)  

1 0.72 1.40 2.10 10.40 0.50 33.30 nsm (-) 

2 0.40 0.85 1.25 6.19 0.47 32.00 nsm (-) 

3 0.40 0.60 1.00 4.95 0.67 40.00 nm (-) 

4 0.30 0.60 0.90 4.46 0.50 33.30 nsm (-) 

5 0.31 0.50 0.81 4.01 0.62 38.27 nm (-) 

6 0.25 1.15 1.40 6.93 0.22 20.00 nsm (+) 

7 0.25 0.70 0.95 4.71 0.36 26.30 nsm (-) 

8 0.30 0.65 0.95 4.71 0.46 31.58 nsm(-) 

9 0.50 0.60 1.10 5.45 0.803 45.45 nm 

10 0.39 0.40 0.79 3.91 0.98 49.36 nm 

11 0.30 0.35 0.65 3.22 0.86 46.45 nm 

12 0.30 0.30 0.60 2.97 1.00 50.00 M 

13 0 1.85 1.85 9.16 0 0 T 

14 0 1.45 1.45 7.18 0 0 T 

15 0 1.26 1.26 6.24 0 0 T 

16 0 0.80 0.80 3.96 0 0 T 

17 0 0.65 0.65 3.22 0 0 T 

18 0 0.60 0.60 2.97 0.66 0 T 

X 0.43 0.65 1.08 5.35 1.00 39.81 nm 

Y 0.25 0.25 0.50 2.48 1.00 50 M 
 

CT = Chromosome type (Abraham and Prasad, 1983) 
TCL = Total chromosome length percentage [(p + q)/Σ(p + q)] x 100 
CI = Centromere index = (p/p + q) x 100  
p = Short arm length 
q = Long arm length 
p + q = Total chromosome length  
nsm =Nearly submetacentric 
nm =  Nearly metacentric 
m = Metacentric 
T = Telocentric 

 

 

chromosome. It has p and q values of 0.72 and 1.67 µm 
respectively.  
Chromosome 2: This chromosome is smaller than 
chromosome 1. It is nearly submetacentric. It has p and q 
values of 0.5 and 0.95 µm respectively.  
Chromosome 3: This is also long but relatively shorter 
than chromosomes 1 and 2. It has p and q lengths of 0.45 
and 0.96 µm respectively.  
Chromosome 4: A nearly submetacentric chromosome 
that has p and q lengths of 0.45 and 0.92 µm 
respectively.  
Chromosome 5: This also is a nearly submetacentric 
chromosome with p and q values of 0.34 and 0.80 µm 
respectively.  
Chromosome 6: This is equally a nearly submetacentric 
chromosome with p and q values of 0.39 and 1.29 µm 
respectively.  
Chromosome 7: This is a nearly submetacentric chromo-
some with p and q values of 0.36 and 0.75 µm 
respectively.  
Chromosome X: This is nearly  submetacentric.  It  has  p 

 
 

 

and q values of 0.35 and 1.38 µm respectively. 
 

 

Group II 

 

Chromosome 8: This is a long nearly metacentric 
chromosome with p and q values of 0.57 and 0.72 µm 
respectively.  
Chromosome 9: This is a nearly metacentric chromo-
some. It has p and q values of 0.45 and 0.56 µm respec-
tively.  
Chromosome 10: This also is a nearly metacentric 
chromosome with p and q values of 0.43 and 0.59 µm 
respectively.  
Chromosome 11: This is a short nearly median chromo-
some with p and q values of 0.37 and 0.46 µm respec-
tively.  
Chromosome 12: This is also a short nearly median 
chromosome with p and q values of 0.36 and 0.38 µm 
respectively.  
Chromosome Y: This is a very small metacentric chromo- 



   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

Figure 1. The unbanded (solid stain) chromosomes of the male NIP and its karyotype (38, XY). 
 

 

some  with  p  and  q  values  of  0.38  and  0.38  µm Chromosome 16: This is a short telocentric chromosome 

respectively. with a q value of 0.93 µm. 
 Chromosome 17: This is also a short telocentric chromo- 
 some with a q value of 0.79 µm. 

Group III Chromosome 18: This is the shortest telocentric chromo- 
 some with q value of 0.71 µm.  
Chromosome 13: This is a long telocentric chromosome. 
It has a q value of 2.1 µm.  
Chromosome 14: This also is a long telocentric chromo-
some, but shorter than chromosome 13. It has a q value 
of 1.69 µm.  
Chromosome 15: This telocentric chromosome has a q 
value of 1.47 µm. 

 
 

The karyotypic data 
 
Below is the karyotypic data obtained from the 
measurement of chromosomal arms, the p/q ratio, the 
centromere indices and the chromosome type of the NIP 
are shown on Table 1. The chromosome arm length and 



    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Figure 2 The karyogram of NIP showing the morphology of the chromosomes.  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Figure 3. The karyogram of the NIP showing the size variation among the 
chromosomes. 



 
 
 

 

p/q ratio of both were observed to be the same in 
chromosome 1, 2, 6, 9, 11, 12, 14 - 18 and Y sex 
chromosome within the S.E measurement while 
differences were obtained in chromosome 3, 4, 5, 7, 8, 
10, 13 and X sex chromosomes but these differences do 
not cause distinction in chromosome type, except in the X 
sex chromosome which showed distinction in 
chromosome type (Oluwole, 2005).  

The karyotypic data obtained was also used to con-
struct the karyogram showing the morphology of each 
chromosomes and size variation amongs the chromo-
somes (Oluwole and Omitogun, 2007). 
 

 

Conclusion 

 
The NIP has a chromosome number of 2n = 38 and a 
nombre fondarmental of 64 which tally with that of the 
Sus scrofa domestica.  

Similarities were found in p/q ratios NIP and exotic pig 
in chromosomes 1, 2, 6, 9, 11, 12, 14 - 18 and Y sex 
chromosome.  

Differences were observed in the p/q ratios of NIP and 
exotic pig in chromosomes 3, 4, 5, 7, 8, 13 and X sex 
chromosome. It is assumed that these information will be 
of tremendous benefit in pig breeding programme aiming 
at enhancing diseases resistance and better adaptation. 
 

 

ACKNOWLEDGEMENT 

 

Our laboratory was funded by the Obafemi Awolowo 
University Research Council Research Grant (URC-
11812 AVT). Acknowledgements are due to Ranjit 
Vandjopathay, Jackie Hughes and O. Mukangi of the 
International Institute of Tropical Agriculture (IITA), 
Ibadan for the assistance in digital photomicrographic 
aspect of this research. 

  
  

 
 

 
REFERENCES 
 
Abraham Z, Prasad PN (1983). A system of chromosome classification 

and nomenclature cytology 48:95-101.  
Adebambo OA (1982). Evaluation of the genetic potential of Nigerian 

indigenous pigs. Proceeding 2
nd

 Wld Cong. Genetic Appl. Livestock 
Prod. Madrid. pp. 543-553.  

Adebambo OA (2003). Animal breeds: A nation’s heritage. Inaugural 
lecture, University of Agriculture, Abeokuta.  

Committee for the Standard Karyotype of Sus scrofa (1988). Standard 
Karyotype of the domestic pig Heriditas 109: 151 – 157.  

CTA (1994). Animal breeding. Mammalian Publishers. pp. 18 – 24. 
Dallai D, Talluri (1969). A Karyotypic study of three spiecies of 

Scincidae (Reptilia) chromosoma (Berl) 27:86-94  
Fairbanks DJ (1999). Genetics: The continuity of life. pp. 304 – 309, 322  

– 326.  
Galman OG, Yerle M, Echard G (1991). The high resolution GTG 

banding karyotype of the Sus scrofa domestica. Genet. Set Evol. 23:  
113s – 116s.  

Ilori JA (1974). Assessing the productive potentials of local breeds of 
pigs. Ann. Conf. Nig. Soc. Anim. Prod. 1:100.  

Mattey R (1945). L’evolution de la formulae chrosominale chez les 
vertebras Experimentia (Basel) 1: 78-86  

Omitogun OG (2004). Analysis of swine genome organization. Evolution 
of G-T-G bands in porcine chromosomes for physical mapping. In: 
(O.J. Oriyo C.O.N. Ikeobi, M.O. Ozoje, T. Omoniyi, and O.B. 

Kehinde, Eds.)..Proceedings of the 29
th

 Annual Conference of the 
Genetics Society of Nigeria., NACGRAB, Moor Plantation, Ibadan pp. 
54-57.  

Oluwole OO (2005). ‘Cytogenetic characterization of the Nigerian Indigenous 
Pig’ Unpublished MSc Thesis Obafemi Awolowo University, Ile-ife. ‘ 
Unpublished MSc Thesis Obafemi Awolowo University, Ile-ife, pp. 1-61  

Oluwole OO, Omitogun OG (2007). ‘The karyomorphology of Nigerian 
indigenouspig chromosomes prepared from leucocyte culture’ Trop. 
Anim. Sci. 10(2):37-40. 


