Animal Research International (2017) 14(1): 2611 – 2618 2611
ISSN: 1597 – 3115 ARI 2017 14(1): 2611 – 2618
www.zoo-unn.org
PHENOTYPIC EVALUATION OF GROWTH TRAITS IN TWO NIGERIAN
LOCAL CHICKEN GENOTYPES
OLEFORUH-OKOLEH, Vivian Udumma, KURUTSI, Romanus Francis and IDEOZU, Hanson
Modhiochi
Department of Animal Science, Rivers State University of Science and Technology, Nkpolu-
Oroworukwo, PMB 5080, Port Harcourt, Rivers State, Nigeria.
Corresponding Author: Oleforuh-Okoleh, V. U. Department of Animal Science, Rivers State
University of Science and Technology, Nkpolu-Oroworukwo, PMB 5080, Port Harcourt, Rivers State,
Nigeria. Email: vivian.oleforuh-okoleh@ust.edu.ng Phone: +234 803 6072087
ABSTRACT
A study was conducted to evaluate growth traits, including body weight, body length,
chest girth, leg length, shank length and shank circumference, using data obtained from
150 mixed sex birds originating from improved Nigerian local chicken (75 normal feather
and 75 naked neck genotypes) of 4 – 16 weeks of age. Body weight of each genotype and
at various ages was regressed on other growth traits studied. During the early growth
phase (4 – 8 weeks), there were significant variations (p<0.05) between the normal
feather and naked neck birds in body weight, body length, leg length and shank
circumference with the normal feather having higher values. No disparity (p>0.05) was
observed in the two genotypes for all traits by the 16
th
week of age. Strong and highly
significant (p<0.001) correlation coefficients (r) were estimated between body weight
and other growth traits in the normal feather (0.62 – 0.94) and naked neck (0.73 – 0.94).
Apart from the 4
th
week of age, strong and positive correlations were obtained between
body weight and the other traits (p<0.001). Significant and high coefficient of
determination R
2
was obtained when body weight was regressed on the other growth
traits in the normal feather and naked neck population (0.89 and 0.90 respectively). The
R
2
was also high (>0.77) for all ages except at 4 weeks of age (0.04), indicating that
most of these traits could be used to forecast body weight precisely at various ages.
Keywords: Local chicken, Normal feather, Naked neck, Body weight, Growth traits, Linear model
INTRODUCTION
Growth is one of the major characteristics of all
living organism. It involves dynamic
physiological changes which commences when
the zygote is formed at the moment of
fertilization and continues till maturity of the
individual. Kor
et al.
(2006) noted that growth in
all animals apart from relating to increase in
body cells and volume is a complex process
controlled by both genetic and non-genetic
factors. Hence, growth in farm animals is a
reflection of an intricate balance between a
great number of endogenous (hormonal,
immunological and genetic) and exogenous
(environmental) factors. Though growth
performance of an animal is a phenotypic
attribute influenced by the environment, to a
larger extent however, it is a manifestation of
the genetic constitution of the animal.
Growth performance and body
conformation traits are therefore important
parameters in assessing the potential of genetic
improvement and development of any livestock
breed/strain. Such knowledge is essential in
planning breeding programmes and in adopting
breeding choices/strategies. There are also
essential in poultry production being
fundamental attributes for assessing growth and
feed efficiency as well as important yardstick in
management and economic decision making
(Assan, 2015).
Oleforuh-Okoleh
et al.
2612
Animal Research International (2017) 14(1): 2611 – 2618
Body weight is usually used as a measure of
growth in farm animals; however numerous
studies have shown that other growth traits
relating to body morphometric measurements
such as body length, shank length and chest
girth can serve as good indicators of growth
(Ige, 2013; Yunusa and Adeoti, 2014). Searle
et
al.
(1989) had earlier reported that skeletal
growth and muscular development are
interconnected. Thus, body morphometric
measurements could be used to - describe body
conformation and predict live weight, examine
relationship among economic traits, evaluate
breed and reproductive performance and to
study interactions between heredity and
environment (Chineke, 2005). This article
describes a study undertaken to evaluate
growth traits in two Nigerian local chicken
genotypes and using information obtained to
predict body weight.
MATERIALS AND METHODS
Site: This study which lasted for 16 weeks was
carried out in the Poultry Unit of the Teaching
and Research Farm of the Department of Animal
Science, Rivers State University of Science and
Technology, Port Harcourt, Nigeria.
Animals: A population of 150 mixed sex birds
originating from improved Nigerian local chicken
(normal feather and naked neck genotypes)
developed by the Poultry Breeding Unit of
Federal University of Agriculture, Abeokuta were
used for the study. The birds were brooded in
two replicates pens per genotype for four weeks
and thereafter randomly allotted to 5 replicates
deep litter pens/genotype with 15 birds per
replicate. The chickens received feed for the
chick phase (day old to 8 weeks of age)
containing 20 % crude protein and 2804 kcal
ME per kg and in the growing phase (8 weeks to
16 weeks of age), the feed composed of 18 %
crude protein and 2605 kcal ME per kg. Feed
and water were provided
ad-libtum
throughout
the experimental period. Standard sanitary and
routine vaccination practices were maintained.
Growth Traits: Six growth traits were
measured on each bird using the methods
described by Gueye
et al.
(1998) from 4 – 16
weeks of age. The traits considered include
body weight (BW), body length (BL), chest
circumference (CC), shank length (SL), shank
circumference (SC), leg length (LL) - the
distance between the hock joint and the pelvic
joint (Adeleke
et al.
, 2011). All measurements
except body weight were done using a flexible
tape. The body weight was obtained using a
sensitive weighing balance. Measurements were
done monthly.
Statistical Analysis: Data on the growth traits
from the two genotypes at four age periods (4,
8, 12 and 16 weeks) were analysed by applying
multivariate analysis of the general linear model
procedure using genotype and age as fixed
factors. Means were considered significant at
p<0.05; such means were separated using
Duncan. Pearson’s correlation coefficients were
estimated between body weight and other
growth traits studied. Regression of body weight
on the independent variables was performed
using stepwise multiple linear regression
procedure. All statistical analyses were carried
out using SPSS (2012).
RESULTS AND DISCUSSION
Analysis of variance exposed some growth
differences between the normal feather and
naked neck type chickens in Nigeria (Table 1).
Much discrepancy (p<0.05) in the variation was
observed between the two genotypes at the
early growing phase (4 – 8 weeks). Normal
feather chickens were heavier, with thicker
shanks, longer body and leg at 4 weeks of age.
The difference between the body weight, body
length, leg length and shank circumference of
the normal feather and naked neck was 7.99,
2.98, 4.31 and 3.58 % respectively (Table 1).
At 8 weeks, except for body length and
shank circumference, there were variations in all
the traits - body weight (9.38 %), chest girth
(5.80 %), leg length (5.02 %) and shank length
(3.13 %) – between the two genotypes, with
the normal feather having greater values.
Conversely, no significant disparity (p>0.05)
was observed in the two genotypes for all traits
by the 16
th
week of age (Table 1).
Phenotypic evaluation of growth traits in two Nigerian local chicken genotypes 2613
Animal Research International (2017) 14(1): 2611 – 2618
Table 1: Effect of genotype and age on growth traits of two Nigerian local chicken
genotypes
Age
Trait
Normal feather (n=75)
Naked neck (n=75)
4 week
BW
312.06 ±7
.71
aw
287.13 ± 6.17
bw
BL
28.52 ± 0.24
aw
27.67 ± 27.67
bw
CG
20.06 ± 0.22
w
19.68 ± 0.20
w
LL
13.68 ± 0.14
aw
13.09 ± 0.17
bw
SL
5.70 ± 0.06
w
5.54 ± 0.07
w
SC
3.63 ± 0.05
aw
3.50 ± 0.05
bw
8 week
BW
931.72 ± 23.85
ax
844.30 ± 21.84
bx
BL
35.17 ± 0.35
x
35
.23 ± 0.40
x
CG
23.78 ± 0.21
ax
22.40 ± 0.42
bx
LL
19.94 ± 0.20
ax
18.94 ± 0.23
bx
SL
7.98 ± 0.07
ax
7.73 ± 0.08
bx
SC
3.86 ± 0.05
x
3.80 ± 0.06
x
12 week
BW
1180.59 ± 32.45
y
1158.15 ± 25.71
y
BL
41.85 ± 0.37
y
40.91 ± 0.35
y
CG
30.37 ± 0.29
ay
29.35 ± 0.2
6
by
LL
20.52 ± 0.20
y
20.76 ± 0.21
y
SL
8.94 ± 0.10
y
8.84 ± 0.01
y
SC
4.41 ± 0.04
y
4.40 ± 0.04
y
16 week
BW
1635.08 ± 43.62
z
1587.93 ± 40.00
z
BL
44.29 ± 0.48
z
44.01 ± 0.36
z
CG
30.99 ± 0.30
z
30.75 ± 0.29
z
LL
22.36 ± 0.28
z
22.07 ± 0.26
z
SL
9.38 ±
0.13
z
9.18 ± 0.14
z
SC
4.53 ± 0.04
z
4.50 ± 0.04
z
BW = body weight, BL = body length, CC = chest circumference, SL = shank length, SC = shank circumference, LL = leg
length.
ab
Meafns on the same row not sharing a common superscript are significantly different (p<0.05).
wxyz
Means on the
same column with different superscript are significantly different (p<0.01)
The present finding is contrary to the report of
Islam and Nishibori (2009) who demonstrated
that naked neck chickens had improved body
weight over their normal feathered
contemporary in hot climates. Rajkumar
et al.
(2011) also reported that growth performance
was significantly higher in the naked neck
chicken. However, the higher body weight and
general body size observed in the present study
affirmed that the indigenous naked neck had
lighter mature weight when compared to the
normal feather (Norris
et al.,
2007; de Almeida
and Zuber, 2010; Magothe
et al.,
2010).
Adekoya
et al.
(2013) found significantly heavier
body weight in the normal feather chicken when
compared to the naked neck counterpart.
Yakubu
et al.
(2009a) observed non-significant
variations in body weight and body
measurements of Nigerian normal feather and
naked neck chickens at maturity.
It is obvious that the growth traits
studied significantly increased (p<0.01) with
age. Ige (2013) recognized that the age of an
animal influences its growth pattern. There was
rapid increase in body weight gain of both
genotypes at the early growth phase (between
4 and 8 weeks) with maximum average daily
gain of 22.13 and 19.90 g/day in the normal
feather and naked neck respectively. Adeniji and
Ayorinde (1990) worked on a population of
Cobb broiler strain and observed a more rapid
weight gain between three to six weeks of age.
Generally, the body weight of the two
genotypes compared favourably with those of
Shaobo, Huaixiang and Youxi chicken of China
at 4 and 8 weeks of age (Zhao
et al
., 2015).
Oleforuh-Okoleh
et al.
2612
Animal Research International (2017) 14(1): 2611 – 2618
Anthony
et al.
(1991) posited that selection age
in relation to age at point of inflection may
contribute to the timing and magnitude of
growth response. Iraqi
et al.
(2002) concluded
that genetic selection at early ages may give
rapid improvement in growth of local strains.
The superior performance of the normal feather
at the early growth phase suggests that this
genotype could be of more genetic importance
for selection towards the development of broiler
strains from Nigerian local chicken.
Relationship between Growth Traits: The
relationships between body weight and all the
body morphometric measurements as well as
the interrelationship between other traits were
positive and very highly significant (p<0.001)
(Table 2). The correlation ranged from 0.62 –
0.94 and 0.73 – 0.94 in the normal feather and
naked neck respectively. In the normal feather,
the highest correlation existed between body
weight and shank length whereas in the naked
neck, it was between body length and body
weight (Table 2). A high correlation coefficient
(0.709) was obtained between body weight and
body length in a population of indigenous
Nigerian chickens raised under extensive
management system (Egena
et al.,
2014).
Okpeku
et al.
(2003) in a report on phenotypic
and genetic variation among local chickens in
Edo State, Nigeria noted that body weight had
strong and positive correlation with body length
and chest girth. In a pairwise correlation
among body measurements, Yakubu
et al.
(2009b) also reported significant strong
correlation between live weight and body length
(0.85), and shank length (0.79) in Arbor broiler
chickens. Haunshi
et al.
(2012) stated that
strong and positive correlations between body
weight and shank length would result in
improvement in shank length of native birds
which is a desirable trait in free range or semi-
intensive system of rearing. This implied that it
is a good trait for selection.
The strong positive association between
body weight and the growth traits measured is
an indication of pleiotropy and provides basis for
possible genetic manipulation and improvement
of the Nigerian local chicken (Yakubu
et al.,
2009a). The goodness of fit as explained by the
degree of linear correlation at 4 weeks of age
indicated weak correlation with between body
weight and all other traits with only the leg
length, chest girth, shank length and shank
circumference exhibiting significant association
with body weight.
The strength and direction of linear
relationship between traits was, however,
strong and positive from 8 weeks of age
(p<0.001) (Table 3). Although previous studies
have indicated positive association between
body weight and other growth traits (Gueye
et
al.,
1998; Guni
et al.,
2013; Fayeye
et al.,
2014), the strength of the association obtained
from this study at four weeks differed from their
findings. Similar observations, however, were
made at 4 weeks by Ojedapo
et al
. (2012) on
two commercial layer strain chickens. Udeh and
Ogbu (2011) also found weak correlations
between body weight and shank length, and
body weight and leg length in Arbor Acre and
Marshall broiler chickens.
The variations observed in the present
study and some previous ones may be
associated with the genetic constitution of the
individual population assessed as well as
environmental factors.
For instance, Ige (2013) found high
positive significant genetic correlation between
body weight and shank length at 4 and 8 weeks
of age in the crossbred Fulani ecotype chickens
in Nigeria. Likewise, Haunshi
et al.
(2012) found
high genetic and phenotypic correlations
between body weight and shank length in Aseel
and Kadaknath native chicken breeds of India at
4 and 6 weeks of age. Yakubu
et al.
(2009b)
also reported strong and positive relationship
between the two traits in Arbor broiler chickens
at 8 weeks.
Body weight: The linear function for predicting
body weight included all growth traits studied,
except shank circumference (Table 4). The high
R
2
(0.89 – 0.90) obtained indicated that these
traits could be used to forecast body weight
precisely. These various morphometric traits
have been earlier described as appropriate
predictor variables for body weight (Adeniji and
Ayorinde, 1990; Chitra
et al.,
2012; Musa
et al
.,
2011; Dahloum
et al.,
2016).
2614
Phenotypic evaluation of growth traits in two Nigerian local chicken genotypes 2613
Animal Research International (2017) 14(1): 2611 – 2618
Table 2: Correlation coefficient between body morphometric measurements
Morphometric measurements
BW
BL
CG
LL
SL
SC
Normal feather
Body weight
(BW)
0.00
0.90
**
0.90
**
0.90
**
0.91
**
0.73
**
Body length (BL)
0.00
0.94
**
0.87
**
0.91
**
0.74
**
Chest girth (CG)
0.00
0.84
**
0.88
**
0.77
**
Leg length (LL)
0.00
0.92
**
0.62
**
Shank length (SL)
0.00
0.73
**
Shank circumference (SC)
0.00
Naked neck
Body weight (BW)
0.00
0.94
***
0.86
***
0.89
***
0.88
***
0.74
***
Body length (BL)
0.00
0.87
***
0.90
***
0.89
***
0.76
***
Chest girth (CG)
0.00
0.81
***
0.81
***
0.75
***
Leg length (LL)
0.00
0.90
***
0.73
***
Shank length (SL)
0.00
0.75
***
Shank circumference (SC)
0.00
** = p<0.01, *** = p<0.001
Table 3: Correlation coefficient between body weight (BW) and other growth traits at
different ages
Traits
Age (weeks
a
)
4
8
12
16
Body length (BL)
0.13
ns
0.58
**
0.78
**
0.77
**
Chest gir
th (CG)
0.15
*
0.58
**
0.80
**
0.79
**
Leg length (LL)
0.20
**
0.82
**
0.68
**
0.72
**
Shank length (SL)
0.19
*
0.82
**
0.80
**
0.63
**
Shank circumference (SC)
0.15
*
0.60
**
0.52
**
0.56
**
a
Using pooled data;
*
p<0.05;
**
p<0.01;
ns
Not significant
Table 4: Estimation model for body weight for the two genotypes
Genotype
Model
R
2
P
-
value
Normal feather
a
BW =
-
1726.70 + 57.91SL + 32.99CG + 52.67LL + 10.81BL
0.89
0.001
Naked neck
a
BW =
-
1677.77 + 41.59BL + 23.59LL + 13.41CG + 41.39SL
0.90
0.001
Age (Week
b
)
4
BW
= 179.63 + 8.88LL
0.04
0.014
8
BW =
-
1408.69 + 165.44SL + 40.51LL + 74.66SC + 8.62CG +
5.59BL
0.81
0.001
12
BW =
-
1850.67+85.73SL + 34.88CG + 20.48BL + 17.13LL
0.78
0.001
16
BW =
-
2990.58 + 58.54CG + 239.06SC + 24.59BL + 28.25LL
0.77
0.001
a
Models derived using stepwise regression,
b
Using pooled data of the two genotypes, BW = body weight, BL = body length, CG
= chest girth, LL = leg length, SL = shank length and SC = shank circumference
In order to improve the prediction power of the
equations, data were categorized according to
age irrespective of the genotype. The stepwise
regression models for body weight on other
growth traits at different ages are also
presented in Table 4. The result depict that at 4
weeks, the best fitted regression equation had
only the leg length included in the model with a
coefficient of determination (R
2
) of 0.04. This
implies that at 4 weeks of age, it would not be
reliable to predict body weight with the other
growth traits employed in the analysis, since
only about 4.0 % of the total variation is
attributable to them. Much significant and
positive association between body weight and
the growth traits studied were observed from 8
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