Open Journal of Genetics, 2013, 3, 280-284 OJGen
http://dx.doi.org/10.4236/ojgen.2013.34031 Published Online December 2013 (http://www.scirp.org/journal/ojgen/)
Effects of coat colour genes on body measurements, heat
tolerance traits and haematological parameters in West
African Dwarf sheep
John S. Decampos1, Christian O. N. Ikeobi1*, Olajide Olowofeso1, Olusiji F. Smith2, Matthew A. Adeleke1,
Mathew Wheto1, David O. Ogunlakin1, Abubakar A. Mohammed1, Timothy M. Sanni1,
Babatunde A. Ogunfuye1, Raman A. Lawal1, Adeyemi S. Adenaike1, Samuel A. Amusan1
1Department of Animal Breeding and Genetics, Federal University of Agriculture, Abeokuta, Nigeria
2Department of Animal Physiology, Federal University of Agriculture, Abeokuta, Nigeria
Email: *ikeobic@yahoo.co.uk
Received 13 June 2013; revised 10 July 2013; accepted 6 August 2013
Copyright © 2013 John S. Decampos et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
With 178 West African Dwarf sheep aged 1 to 3 years,
a study was conducted to investigate the effects of
coat colour genes on body measurements, heat toler-
ance traits and haematological parameters. Body
measurements considered included body length, hair
length, ear length, hip width, tail length, height at
withers, rump height, fore cannon bone length, chest
depth, heart girth and body weight. Heat tolerance
traits considered were skin temperature, rectal tem-
perature, pulse rate and respiratory rate. Blood sam-
ples were collected for the evaluation of white blood
cell (WBC), red blood cell (RBC), haemoglobin
(HGB), haematocrit (HCT), mean corpuscular vol-
ume (MCV), mean corpuscular haemoglobin (MCH),
mean corpuscular haemoglobin cell (MCHC), red cell
distribution width (RDW), platelets (PLT), mean
platelets volume (MPV), platelets distribution width
(PDW) and plateletcrits (PCT). Results showed that
coat colour gene (CCG) had significant (P < 0.01) ef-
fect on rump height and tail length. Animals with
black (BB) coat colour had the highest mean value for
rump height (57.80 ± 1.29 cm) and tail length (22.10 ±
0.89 cm), while brown (Bb) coat colour had the least
value of 53.00 ± 6.00 cm for rump height and 17.50 ±
0.50 cm for tail length. The CCG had significant (P <
0.01) effect on body temperature and pulse rate, with
the grey/mouflon (Ag) colour possessing the highest
body temperature (38.90˚C ± 0.22˚C), and Bb having
the least value of 37.20˚C ± 0.35˚C. White/tan (Awt)
had the highest pulse rate of 28.90 ± 0.66 beats/min
and Bb had the least value of 20.00 ± 2.00 beats/min.
The CCG had significant (P < 0.01) effect on RBC
and MPV with brown (Bb) colour having the highest
RBC counts (18.20 ± 0.00 L) and badgerface (Ab)
having the least value (11.50 ± 0.62 L). The Bb had
the highest value (5.60 ± 0.00 fL) for MPV and Ab had
the least value (4.70 ± 0.15 fL). Sheep with Bb and Ab
were found to withstand heat stress better than oth-
ers.
Keywords: Coat Colour Gene; Haematological
Parameters; Morphological Indices; Sheep
1. INTRODUCTION
The animal performance is an expression of genetic and
environmental factors [1]. Genetic factors depict innate
factors. They are the factors which are inherent and
could re-occur from generation to generation. Coat col-
our which is a genetic factor is known to adapt animals
to different climatic zone s and has considerab le influence
on the performance of various stocks [2-3]. The West
African Dwarf (WAD) sheep is one of the breeds of
sheep in Nigeria with a small, compact body which may
be all white, all black, all brown, or spotted black or
brown on a white coat. It is predominantly found within
the rainforest, mangrove swamps and coastal regions in
southern Nigeria [4].
Growth, often defined as the increase in size or body
weight at a given age, is one of the important selection
criteria for the improvement of meat animals such as
sheep [5]. Body measurements can be used in assessing
growth rate, feed u tilisation an d carcass characteristics in
farm animals [6]. Body measurements are divided into
skeletal and tissue measurements according to [7]. The
*Corresponding author.
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J. S. Decampos et al. / Open Journal of Genetics 3 (2013) 280-284 281
height at withers is part of skeletal measurements,
whereas the heart girth is part of tissue measurements [8].
Body measurements of meat animals have been found to
be useful in quantifying the body size and shape [9] and
necessary for estimating genetic parameters [10]. Heat
tolerance is the ability to be comfortable when external
temperature rises. The common heat tolerance traits in-
clude sweating rate, heart and breathing rates, rectal
temperature, and skin temperature [11]. When the
physiological mechanism of the animal fails to negate
the excessive heat load, the rectal temperature increases.
At the same time, such exposure of sheep to heat stress
evokes a series of drastic changes in the biological func-
tions, which include a decrease in feed intake efficiency
and utilization, disturb ances in water, protein, en erg y and
mineral balances, enzymatic reactions, hormonal secre-
tions and blood metabolites [12].
Haematological parameters are those parameters that
are related to the blood and blood-forming organs [13].
The blood consists of components broadly divided into
three parts: leukocytes, erythrocytes and platelets, and
further sub-divided into haemoglobin (Hb), red blood
cells (RBC), packed cell volume (PCV), mean corpuscu-
lar haemoglobin (MCH), etc. These traits play important
roles in animal immune function and disease resistance
[14]. The use of blood examination as a way of assessing
the health status of animals has been well documented
[15]. This is because they play a vital role in physiologi-
cal, nutritional and pathological status of the animals
[16].
Although much work has been carried out to assess the
effects of diseases and nutrition on sheep in Nigeria, lit-
eratures on the tolerance of sheep to heat stress and its
effects on productivity are however limited [17]. Infor-
mation on the physiological responses of sheep to heat
stress will not only assist in the provision of adequate
housing, feed and other environmental conditions, but
also be useful in the selection of suitable breeds for each
ecological niche [17]. The knowledge of the response of
different coat colour types of heat stress will help in the
selection of suit able breeds for each ecological niche.
The study of haematological parameters in WAD
sheep could predetermine the genetic potential of an
animal for selection [18].
This study was therefore carried out to investigate the
influence of the coat colour gene on the productive and
adaptive traits in WAD sheep in Nigeria.
2. MATERIALS AND METHODS
2.1. Study Location and Sample Size
This study was carried out in Odeda Agro-ecological
Zone of Ogun State, Nigeria. One hundred and seventy
eight WAD sheep were sampled for eight months. West
African Dwarf sheep in the zone are usually reared under
the free-range system whereby the owners occasionally
feed their animals with kitchen wastes, cassava and yam
peels or whole cassava and corn shaff in the morning
before they are left to roam about the houses and sur-
rounding. There was no known common browse plant in
the studied area, except that the animals browse on
whatever comes their way. There was no known deliber-
ate veterinary or ethno-veterinary practice engaged in by
the livestock owners.
2.2. Data Collection and Analysis
Exactly 7 ml of blood was collected via the jugular vein
puncture of each animal using a 10 mm gauge syringe
into sample bottles containing the antico agulant, ethylene
diamine tetra acetic acid (EDTA). Sample bottles were
well-labelled for proper identification and blood samples
collected were transported to the laboratory for the
analysis of the haematological parameters which in-
cluded white blood cell (WBC), red blood cell (RBC),
haemoglobin (HGB), haematocrit (HCT), mean corpus-
cular volume (MCV), mean corpuscular haemoglobin
(MCH), mean corpuscular haemoglobin cell (MCHC),
red cell distribution width (RDW), platelets (PLT), mean
platelets volume (MPV), platelets distribution width
(PDW) and plateletcrits (PCT).
Phenotypic measurements were taken on sampled
sheep on site. These included both the quantitative and
qualitative measurements of the body. Th e major qualita-
tive description taken was the coat colour. Using the
fleece colour in sheep as earlier observed by [19], the
major coat colour gene variations observed included the
white/tan (Awt), black (BB), spotted brown (Bb), grey/
mouflon (Agt) and badgerface (Ab). The age and sex of
the animals were also noted. Quantitative measurements
of the body taken included body weight using a spring
balance attached to a scaffold, body length, heart girth,
height at withers, ear length, hair length, rump height,
hip width, tail length, fore cannon bone length and chest
depth with the use of a measuring tape. Brief descrip-
tions of the quantitative measurements are as follows:
Height at withers: which is the dorsal midline at the
highest point on the wither.
Tail length: which is the distance between the tip of
the tail and the base end tail touching the body of the
animal.
Ear length: distance between the tip of the ear and the
base of the ear.
Body length: distance between the tip of the mouth
and the base of the tail.
Heart girth: the body circumference immediately
posterior to the front legs or the body circumference on
the fore hips.
Height at hips: it will be measured mid sacrum on the
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J. S. Decampos et al. / Open Journal of Genetics 3 (2013) 280-284
Copyright © 2013 SciRes.
282
dorsal mid-line. colour genes with both black colours having the highest
mean values and the brown possessing the least values
for both parameters.
Width at hips: distance between the lateral surfaces on
the point of shoulder. Table 2 shows the least square means of the heat
stress parameters as influenced by the coat colour genes.
The results show that th e body temperature and the pu lse
rate are significantly (P < 0.01) affected by the coat col-
our genes with the grey/mouflon (Ag) having the highest
body temperature and the brown (Bb) possessing the
least body temperature, and the white/tan (Awt) colour
gene having the highest pulse rate and the brown (Bb)
having the least pulse rate.
Fore cannon length: distance between the leg bones.
The body temperature, rectal temperature, pulse rate
and respiratory rate of the animals were also taken with
the use of a thermometer and stethoscope, respectively.
The management system, environmental temperature,
geographical locations of the animals, and time of the
day were also considered. Data obtained for haemato-
logical parameters, heat tolerance traits and body meas-
urements were analyzed using the General Linear Model
Procedure of [20]. The model employed was of the form: Table 3 shows the least square means of the haemato-
logical parameters as influenced by the coat colour genes.
The results showed that the red blood cell and the mean
platelets volume were significantly (P < 0.01) affected by
the coat colour genes with the brown (Bb) colour genes
having the highest red blood cell count and the badger-
face (Ab) having the least red blood cell count. The mean
platelets volume showed the brown colour (Bb) with the
highest value and the badgerface had the least value of
the mean platelets volume.

ijkij kijk
jk
YMSPSP
 
where Yijk = The parameter of interest, µ = Overall mean
for the parameter of interest, Mi = Fixed effect of ith age
(i = 1 - 3), Sj = Fixed effect of the jth sex (j = 1 - 2), Pk =
Fixed effect of the kth coat colour gene (k = 1 - 5),

j
k = Interaction effect of the jth sex and kth coat
colour genes and
SP
ijk
= Random error associated with
each record.
Correlation was also computed using [20] to ascertain
relationships among measurable traits. Means that dif-
fered significantly were separated using Duncan’s Multi-
ple Range Test [21].
4. DISCUSSION
From the results of the expe riment presented in Tables 1
and 2, the high temperature is as a result of the effect of
the high absorption rate of the ultraviolet rays of the
sunlight by the pigments on the skin of the animals and
the influence of the environmental temperature. This
agrees with the result of [22] who reported that surface
body temperature of white cattle was consistently lower
than coloured cattle. The authors further concluded that
3. RESULTS
Table 1 shows the least square means of the effects of
coat colour genes on the linear body measurements of the
WAD sheep. It revealed that the rump length and the tail
length were significantly (P < 0.054) affected by the
Table 1. Least square means ± standard error of the linear body measurements as affected by colour gene.
Colour
Body measurements White/tan (Awt) Badgerface (Ab) Grey/mouflon (Ag) Black (BB) Brown (Bb)
Body weight (kg) 17.89 ± 0.69 19.91 ± 1.13 16.19 ± 2.44 18.04 ± 1.52 19.10 ± 6.10
Height at withers (cm) 54.78 ± 0.52 54.31 ± 0.91 52.70 ± 1.96 54.83 ± 1.42 51.25 ± 1.75
Rump length (cm) 56.66 ± 0.49ab 56.14 ± 0.71ab 55.20 ± 1.87ab 57.75 ± 1.29a 53.00 ± 6.00b
Fore cannon bone length (cm) 13.82 ± 0.19 13.53 ± 0.23 12.35 ± 0.43 13.53 ± 0.43 12.50 ± 0.50
Chest depth (cm) 27.97 ± 0.41 28.19 ± 0.46 26.40 ± 1.18 27.30 ± 0.88 26.75 ± 3.25
Hip width (cm) 12.75 ± 0.23 13.65 ± 0.38 13.60 ± 0.70 13.33 ± 0.67 14.00 ± 2.00
Ear length (cm) 10.68 ± 0.18 10.31 ± 0.29 10.00 ± 0.49 10.33 ± 0.39 11.00 ± 1.00
Heart girth (cm) 64.47 ± 0.77 65.22 ± 1.15 60.60 ± 2.65 61.60 ± 2.92 60.50 ± 7.50
Tail length (cm) 20.82 ± 0.33ab 21.39 ± 0.51a 21.80 ± 1.13a 22.13 ± 0.89a 17.50 ± 0.5a
Hair length (cm) 4.16 ± 0.11 4.11 ± 0.14 4.70 ± 0.39 4.60 ± 0.40 4.75 ± 0.25
Body length (cm) 69.72 ± 0.89 69.87 ± 1.16 70.6 ± 2.63 71.87 ± 1.74 69.00 ± 1.00
Different superscripts of a and b in the same row mean a significant difference between the values at P < 0.05.
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J. S. Decampos et al. / Open Journal of Genetics 3 (2013) 280-284 283
Table 2. Least square means ± standard error of heat stress parameters as influenced by colour genes.
Colour
Heat tolerance traits White/tan (Awt) Badgerface (Ab) Grey/mouflon (Ag) Black (BB) Brown (Bb)
Body temperature (˚C) 38.65 ± 0.14a 38.78 ± 0.11a 38.87 ± 0.22a 38.86 ± 0.22a 37.15 ± 0.35b
Pulse rate (beats/min) 28.91 ± 0.66a 26.51 ± 0.74a 26.00 ± 1.23ab 27.87 ± 1.27a 20.00 ± 2.00b
Respiratory rate (breaths/min) 17.80 ± 0.48 20.63 ± 1.30 18.90 ± 2.02 21.33 ± 1.55 14.00 ± 4.00
Rectal temperature (˚C) 39.22 ± 0.13 39.20 ± 0.10 39.15 ± 0.23 39.29 ± 0.19 38.60 ± 0.60
Different superscripts of a and b in the same row mean a significant difference between the values at P < 0.05.
Table 3. Least square means ± standard error of haematological parameters as influenced by colour genes.
Colour
Haematological Parameters White/tan (Awt) Badgerface (Ab) Grey/mouflon (Ag) Black (BB) Brown (Bb)
WBC(L) 11.42 ± 0.96 8.46 ± 1.28 7.79 ± 2.66 11.65 ± 2.11 0.00 ± 0.00
RBC(L) 11.64 ± 0.39b 11.54 ± 0.62b 14.61 ± 1.60ab 12.77 ± 1.08ab 18.16 ± 0.00a
HGB(g/l) 100.74 ± 3.83 100.00 ± 6.09 132 ± 18.37 110.00 ± 9.82 150.00 ± 0.00
HCT(%) 30.70 ± 1.04 30.69 ± 1.68 39.49 ± 4.57 32.62 ± 2.77 45.20 ± 0.00
MCV(fl) 26.50 ± 0.23 26.67 ± 0.30 27.34 ± 1.18 25.69 ± 0.49 24.90 ± 0.00
MCH(Pg) 8.54 ± 0.06 8.49 ± 0.09 8.83 ± 0.29 8.56 ± 0.12 8.20 ± 0.00
RDW(%) 17.69 ± 0.14 17.64 ± 0.19 18.22 ± 0.42 17.93 ± 0.27 19.40 ± 0.00
PLT(L) 209.71 ± 10.17 187.33 ± 15.50 161.60 ± 16.96 173.6 ± 18.27 71.00 ± 0.00
MPV(F/L) 4.88 ± 0.03ab 4.70 ± 0.15b 5.04 ± 0.12ab 4.94 ± 0.06ab 5.60 ± 0.00a
PDW(%) 13.19 ± 0.03 12.66 ± 0.39 13.05 ± 0.04 13.13 ± 0.03 12.90 ± 0.00
PCT(%) 1.29 ± 1.19 0.09 ± 0.01 0.08 ± 0.01 0.08 ± 0.01 0.04 ± 0.00
Different superscripts of a and b in the same row mean a significant difference between the values at P < 0.05. Abbreviations are as defined within text.
with exposure to sunlight, coloured cattle should be more
adapted to tropical or sub-tropical conditions in confined
situations.
The highest pulse rate was recorded for white/tan (Awt)
colour gene. This result do es not agree with the report of
[23] which showed that heat flow from the environment
into the body of a black steer on a hot sunny day was
30% greater than that of a white steer thereby resulting in
an increase in the pulse rate of the black steer. The possi-
ble reason for this result could be due to the environ-
mental influence on the animals.
Furthermore, from Table 3, it could be deduced that
the highest red blood cell count possessed by the brown
coat animals could be as a result of exposure of the skin
to the sunlight and due to heat stress prevalence in the
environment. This agrees with the results of [24] which
reported significant effect of coat colour genes on the red
blood cell, but the author however recorded the black
coat colour as having the highest red blood cell count
amongst other colours. The high red blood cells count in
this study also agrees with the findings of [25] which
reported an increase in the quantity of the red blood cell
with heat stress. Based on the results of study, it can be
concluded that WAD sheep with brown (Bb) and bad-
gerface (Ab) coat colour genes could adapt and survive
better than others in the tropical environment.
In conclusion, the influence of the coat colour genes
on animals could determine the adaptability and surviv-
ability of the animal in a particular environment. The
genetic potential of an animal could be predetermined
through the influence of the coat colour on heat stress
traits and the haematological parameters. However, fol-
low-up resear ch should be carried out on the influence of
the coat colour genes on the morphological indices of
West African Dwarf sheep using an intensive manage-
ment system. In this study, both West African Dwarf
sheep with brown (Bb) and badgerface coat colour (Ab)
were found to withstand heat stress better than sheep
with other coat colours.
REFERENCES
[1] Martojo, H. (1992) Genetic improvement in livestock.
PAU IPB, Bogor, 1-20.
Copyright © 2013 SciRes. OPEN ACCESS
J. S. Decampos et al. / Open Journal of Genetics 3 (2013) 280-284
284
[2] Odubote, I.K. (1994) Influence of qualitative traits on the
performance of West African Dwarf goats. Nigerian
Journal of Animal Production, 21, 25-28.
[3] Ebozoje, M.O. and Ikeobi, C.O.N. (1998) Colour varia-
tion and reproduction in West African Dwarf goats. Small
Ruminant Research, 27, 125-130.
http://dx.doi.org/10.1016/S0921-4488(97)00045-X
[4] Yakubu, A., Kuje, D. and Okpeku, M. (2010) Principal
components as measure of size and shape in Nigerian in-
digenous chickens. Thai Journal of Agricultural Science,
42, 167-176.
[5] Afolayan, R.A., Adeyinka, I.A. and Lakpini, C.A.M.
(2006) The estimation of live weight from body meas-
urements of Yankassa sheep. African Journal of Bio-
medical Research, 5, 81-82.
[6] Brown, J.E., Brown, C.J. and Butts, W.T. (1973) Evalu-
ating relationships among immature measures of size,
shape and performance on beef bulls I: Principal compo-
nent as measures of size and shape in young Hereford and
Angus bulls. Journal of Animal Science, 36, 1010-1020.
[7] Essien, A. and Adesope, O.M. (2003) Linear body meas-
urements of N’dama calves at 12 months in a Southwest-
ern zone of Nigeria. Livestock Research for Rural De-
velopment, 15, 4.
[8] Blackmore, D.W., McGulliard, L.D. and Lush, J.L. (1958)
Genetic relationship between body measurements at three
ages in Holstein. Journal of Dairy Science, 41, 1045-
1049.
http://dx.doi.org/10.3168/jds.S0022-0302(58)91048-8
[9] Ibe, S.N. and Ezekwe, A.G. (1994) Quantifying size and
shape difference between Muturu and N’dama breeds of
cattle. Nigerian Journal of Animal Production, 21, 51-58.
[10] Chineke, C.A. (2000) Characterization of physical body
traits of domestic rabbit in humid tropics. Proceedings of
the 25th Annual Conference of Nigerian Society for Ani-
mal Production, March 2000, Umudike, 237-238.
[11] Susan, C. (2010) University of Maryland Extension, So-
lution in your community. http://www.sheepandgoat.com/
[12] Maraia, I.F.M., El-Darawanya, A.A., Fadiel, M.A.M. and
Abdel-Hafez, M.A. (2005) Physiological traits as affected
by heat stress in sheep. Indian Journal of Animal Health,
42, 20-21.
[13] Stenesh, J. (1975) Dictionary of Biochemistry. Wiley-
Interscience Publication, London, 137.
[14] Gong, Y.F., Lu, X., Wang, Z.P., Hu, F., Luo, Y.R., Cai,
S.Q., Qi, C.M., Li, S., Niu, X.Y., Qiu, X.T., Zeng, J. and
Zhang, Q. (2010) Detection of quantitative trait loci af-
fecting haematological traits in swine via genome scan-
ning. BMC Genetics, 11, 56-57.
http://dx.doi.org/10.1186/1471-2156-11-56
[15] Muhammad, N.O., Oloyede, O.B., Owoyele, B.V. and
Olajide, J.E. (2004) Deleterious effect of defatted Termi-
nalia catappa seed meal-based diet on haematological
and urinary parameters of albino rats. NISEB Journal, 4,
51-57.
[16] Kakade, M.L., Simons, N.R., Liener, I.E. and Lambert,
J.W. (1972) Biochemical and nutritional assessment of
different varieties of soybean. Journal of Agriculture and
Food Chemistry, 20, 87-90.
http://dx.doi.org/10.1021/jf60179a024
[17] Butswat, I.S., Mbap, S.T. and Ayibantoye, G.A. (2000)
Heat to lerance of shee p in Bauchi. Nigerian Tropical Ag-
riculture, 77, 265-268.
[18] Alul, J.S., Ashok, S. and Klirn, F.H. (1995) Effect of
haemoglobin types on reproductive tracts in Jersey cattle.
Indian Veterinary Journal, 12, 642-644.
[19] Ryder, M.L. (1980) Fleece colour in sheep and its inheri-
tance. Animal Breeding Abstract, CAB, 48, 305-322.
[20] SAS. (1999) SAS User’s Guide. Version 8.1, SAS
Institute Inc., Cary.
[21] Gomez, A.K. and Gomez, A.A. (1984) Statistical proce-
dure for agricultural research. 2nd Edition, John Wiley
and Sons Inc., New York, 680.
[22] Arp, S.C., Owens, F.N. , Armbruster, S.L.V. and Scott, L.
(1982) Relationships of coat colour, body surface tem-
perature and respiration rate in feedlot steers. Oklahoma
Agricultural Experimental Station.
[23] Hutchinson, J.C.D., Brown, G.D. and Allen, T.E. (1976)
The effects of solar radiation on the sensible heat ex-
change of mammals. In: Johnson, H.J., ed., Progress in
Animals Biometeorology, 42.
[24] Sanusi, A.O. (2012) Effects of coat colour genes on heat
stress and tolerance to Haemonchus contortus among
West African Dwarf sheep. M. Agric. Dissertation, Fed-
eral University of Agriculture, Abeokuta.
[25] Borges, S.A., Ariki, J. and Cummings, K.R. (2003) Die-
tary electrolyte balance for broiler chickens exposed to
thermo-neutral and heat stress environments. Poultry
Science, 82, 428-435.
Copyright © 2013 SciRes. OPEN ACCESS