By Misbah, F; Derese, M; Haiyre, G (2023).
|
Greener Journal of Agricultural Sciences ISSN: 2276-7770 Vol. 13(4), pp. 217-226, 2023 Copyright ©2023, Creative Commons Attribution 4.0 International. |
|
Click on Play button...
Prediction of Afar Goat
Breed Live Body Weight to Facilitate Breed Improvement and Husbandry Practice
Feki Misbah1*; Mohammed Derese1; Genne Haiyre1
1Wolkite University, P.O. Box 07, Wolkite, Ethiopia.
|
ARTICLE INFO |
ABSTRACT |
|
Article No.: 092023096 Type: Research |
This study was undertaken in Afar Regional state, Ethiopia with the
aim of developing a body weight prediction model from linear measurements.
Stratified random sampling was employed to select the study area and
households. A total of 891 goats (823 female and 68 male) above six months
of age were used for body measurements. Each measurement was sexed and aged
using dentition. Body measurements were analyzed
using the Generalized Linear Model of the Statistical computing R. Tukey’s HSD post-hoc test was used to separate means if
analysis of variance showed significance. Pearson’s correlation coefficients
were used to select variables that have a strong correlation with body
weight. Then stepwise regression procedure of R was employed to identify a
model. The overall mean body weight was 23.8 kg. Body measurements for males
and females were (26.44 and 20.87 kg)
for body weight, (64.8 and 59.5 cm) for chest girth, (63.1 and 58.9 cm) for body
length, (59.6 and 55.4 cm) for height at wither and (13.3 and 12.4 cm) for
pelvic width respectively. In all measurements, males were significantly
(P<0.01, P<0.05) heavier than females. Most body measurements
increased consistently as age advanced. Most of the linear parameters
depicted positive and highly significant (P<0.01) correlation with body
weight. The body weight of the Afar goat breed could be predicted with
higher accuracy from chest girth (CG) and body length (BL) in pastoral areas
where there is limited weighing scale to improve the breed, husbandry
practice and weight based marketing. |
|
Accepted: 06/10/2023 Published: 18/10/2023 |
|
|
*Corresponding Author Feki
Misbah E-mail: misbahfeki@
gmail.com |
|
|
Keywords: |
|
|
|
|
In Ethiopia, the diversified goat population
kept by pastoral and agro-pastoral substantially contributes to the livelihood
of the rural poor and the country’s economy at large (Haile et al., 2019). Despite their diversified importance and
large population size, productivity per unit of animal is very low due to
traditional production system. Lack of appropriate breeding strategies, poor
husbandry practice and poor understanding of the market system were indicated
as the main reasons (Gebremedhin et al, 2015; Zewdie and Welday, 2015).
The majority of Ethiopian goat populations
(about 70%) are located in the arid and semi – arid areas where they are kept
in large flocks by pastoralists (FARM Africa, 1996). The type of goat breeds in
these unfavorable environment are determined by the ability to survival under
the prevailing fluctuating feed scarcity, disease challenges, low level of
management and harsh climate (Laird, 2002). Genetic improvement is currently
being centered on indigenous breeds because they have long been adapted to
extreme harsh environmental conditions and might be more productive in their
own environment than the exotic breeds (Rege, 2003).
To date,
community-based breeding programs can be viewed as part and parcel of a comprehensive
conservation based genetic improvement activity without any significant
additional costs. Community‐Based Breeding Programmes (CBBPs), which focus on indigenous stock and
consider owners’ needs, views, decisions and active participation, from inception
through to implementation, have been identified as programmes
of choice (Muller et al., 2015).
However, genetic
improvement efforts are constrained by absence of performance and pedigree
recording, illiteracy, poor infrastructure, diseases, lack of market linkage
and so on (Haile et al., 2019). The mobile nature of pastoral in search of feed
also makes it difficult to take performance recording by technicians. Additionally,
the marketing system of small ruminants is also traditional – price is determined
by buyers or middle men – which mostly makes pastoral disadvantageous. Live
weight based pricing system have been tried by government of Ethiopia, but with
little success (Gebremedhin et al, 2015). At
smallholder level, affordability and accessibility of weighting scale was the
limiting factor. Hence easily applicable alternative methods are needed.
Measurement
and recording of live body weight is one of the key traits used as selection
criteria of best goats, compare performance change due to management, to
evaluate genetic progress as well as live weight pricing of animals. Therefore,
this paper aims to develop context specific live weight estimation model for
afar goat breed.
Afar National Regional State (ANRS) is one of the eleven
states of Ethiopia.
The Region is located in the lowland of Great Rift Valley between 80
45’ to 140 27’ latitude North and 39o 51’ to 420
23’ longitude East and covers an area of 100,860 km2. The Region
has an estimated population of 1.9 million (CSA, 2019) of which 90% are
pastorals whereas 10% represent agro-pastoral. About half of the Region (51.4%) has arid
agro-climate which falls with an elevation ranging from 400 to 900 meters. Even
to the worst, one – third (35.5%) of the Region is categorized as desert
agro-climate due to its lower altitude which is below 400 meters above sea level.
The annual temperatures vary from 18oC to 45oC. The
rainfall ranges from 500mm in the semi-arid western escarpments to 150mm in the
arid zones (Nigatu, 1994; Solomon, 2006). The study
was conducted in Aysaita district, where there is
less mixing of the goat population with neighboring breeds.
Stratified
sampling procedure was employed. The district was stratified into pastoral and
agro pastoral production system. Afterward, two pastoral and one agro-pastoral peasant
association were selected based on availability of goat flock. The samples size for physical description of a breed
depends upon the precision required and the variability in the sample
population. Coefficients of variation on body measurements of mature goats were
observed to range between 10 and 30% (FARM Africa, 1996). For 5% statistical
significance, 100 to 300 mature goats are required from representative site
(Peters, 1985).
Bearing this in mind, a total of 891 individual goats above six months of age
were used for body measurements. About 610 and 281 heads of goat were sampled
from 32 pastoral and 22 agropastoral
households, respectively. On average 19 and 13 goats per household were
measured from pastoral and agropastoral production
systems respectively. A maximum of 30 and 20 goats were restricted from an
individual household in pastoral and agropastoral
system, correspondingly even if the household owe large flock size.
Data was generated by employing field
measurements. The following body measurements: Chest Girth
(CG), Body Length (BL), Height at Wither (HW), Pelvic Width (PW), Ear Length
(EL), Horn Length (HL) and Scrotum Circumference (SC) were taken using tailors
measuring tape while body weight was measured using 50 kg capacity suspended
spring balance with 0.2 kg precision. The definition and way of body weight and
linear measurements were described in Appendix Table 1. Body condition score
(BCS) was assessed subjectively and scored using the 5 point scale (1=very
thin, 2=thin, 3= average, 4=fat and 5=very fat/obese) for both sexes. BCS of an
animal was scored by feeling the back bone with the thumb and the end of the
short ribs with finger tips immediately behind the last ribs (McGregor, 2007; Girma, 2009).
The detail description of scoring is indicated in Appendix Table 2.
All measurements were taken in the morning
before the animals were fed. Each of the animals selected for measurement was
sexed and aged according to Girma and Alemu (2008)
using permanent teeth eruption. Thus, goat with fully grown milk teeth that
started to spread out and zero pair of permanent incisor eruption (0PPI)
representing 6 to 13 months of age and goats with erupted and growing first
pair of permanent incisor (1PPI) representing 14 to 17 months of age. In the
same way, 2PPI, 3PPI and 4PPI represent 18 to 23 months, 24 to 36 months and
above 36 months of age, respectively.
Quantitative
traits (body weight and some linear body measurements) were analyzed using the
Generalized Linear Model of the Statistical computing R version 4.1.2, 2021. Tukey’s HSD post-hoc test was used to separate means if
analysis of variance showed significance. The statistical Model 1 was used to
analyze body weight and linear body measurements:
Where: Yijk
= the observed l in the ith Production System (PS), jth
sex class and kth age group;
µ = Overall mean;
Ai = the fixed effect of PS (i=1, 2: where 1= pastoral
and 2= agropastoral);
Sj = Fixed effect of sex (j = 1, 2:
where, 1= male and 2= female);
Dk = Fixed effect of age (k = 1, 2, 3, 4 and 5: where, 1= age group at 0PPI,
1PPI, 2PPI, 3PPI and 4PPI, respectively) and possible interactions.
eijk = Random error.
Pearson’s correlation coefficients between
body weight and other body measurements of the population for each sex and
dentition categories were estimated to select variables that have a strong
correlation with body weight. Then body weight was regressed on linear
measurements and BCS for each sex and age group using stepwise regression
procedure of R version 4.1.2, 2021 to identify a model. Each of the available
predictors was evaluated with respect to how much R2 would be increased by adding it to the
model. Best fitted model was selected based on highest coefficient of
determination R2 and lowest Mallow’s Cp value that is close
to p+1, where p is the number of predictor
variables in the model (Mallows, 1973). Model 2 and
3 were used to develop the best linear regression equation for female and male
goats, respectively.
Yj = β0 +
β1X1 + β2X2 + β3X3 + β4X4 + β5X5 + β6X6+ ej ------------ Model 2
Where: Yj = the
dependent variable body weight,
β0 = the intercept,
X1, X2, X3, X4, X5 and X6 are the independent
variables such that body length, chest girth, height at wither,
chest width, pelvic width and body condition score respectively.
Yj = β0 +
β1X1 + β2X2 + β3X3 + β4X4 + β5X5 + β6X6 +
β7X7 + ej Model
3
This model
is similar with that of female except that scrotal circumference included in
the model as independent variable.
β1, β2, ..., β6 is regression coefficient of the
variables X1,X2,...,X 6
ej = the residual error.
The body weight and linear measurements of sampled
population were summarized in Table 1. Body weight and linear measurements
varies among age, sex and to some extent the production systems. Availability
of few breeding male for screening was because most of the male goats are
culled at young age as mating control strategy for breed improvement (Misbah et al., 2015) as well as to increase production
efficiency and minimize handling problem. The net effect of this act is
availability of very few male animals. A similar limitation was faced by Fajemilehin and Salako (2008)
who used smaller proportion of male (84 heads) to study the physical
description of West African Dwarf (WAD) goat, Nigeria.
Table
1: Least square means and standard error
(LSM + SE) for main effects of dentition (PPI), sex and production system (PS) and sex by age interaction effect on body weight
(kg) and linear measurements of Afar goat breed.
|
Effects & level
|
N |
Body
weight |
CG |
CW |
BL |
HW |
PW |
BCS |
HL |
EL |
SC |
|
Overall |
891 |
23.8
± 0.21 |
62.17
+ 0.23 |
7.00 +
0.06 |
60.96
+ 0.25 |
57.5
± 0.20 |
12.9 +
0.04 |
2.3 +
0.04 |
21.4 +
0.28 |
12.7 +
0.12 |
23.4 +
0.42 |
|
R2 |
|
0.50 |
0.54 |
0.24 |
0.41 |
0.36 |
0.33 |
0.18 |
0.63 |
0.06 |
0.44 |
|
C.V |
|
14.04 |
5.5 |
14.04 |
6.17 |
5.15 |
9.75 |
33.6 |
20.27 |
11.24 |
12.24 |
|
Dentition |
|
*** |
*** |
*** |
*** |
*** |
** |
NS |
*** |
*** |
*** |
|
0PPI |
127 |
19.10 + 0.31a |
56.3 + 0.34a |
6.2 + 0.10a |
56.1 + 0.37a |
54.0
± 0.29 a |
11.3 +
0.12a |
2.60 + 0.07a |
14.8 + 0.43a |
11.96 + 0.15a |
19.9 + 0.58a |
|
1PPI
|
87 |
21.43 + 0.55b |
60.2 + 0.40b |
6.8 + 0.11b |
59.8 + 0.44b |
56.2
± 0.34 b |
12.5 +
0.15b |
2.51 + 0.08a |
18.1 + 0.50b |
12.91 + 0.18b |
22.3 + 0.80b |
|
2PPI |
58 |
23.96 + 0.45c |
62.7 + 0.48c |
7.3 + 0.14c |
60.4 + 0.53c |
57.9
± 0.41 c |
13.1 +
0.18c |
2.26 + 0.09b |
21.7 + 0.06c |
12.87 + 0.22b |
24.0 + 0.98bc |
|
3PPI |
142 |
26.33 + 0.32d |
65.2 + 0.34d |
7.3 + 0.10c |
63.3 + 0.37d |
59.7
± 0.29 d |
13.4 +
0.13c |
2.33 + 0.04b |
23.6 + 0.42d |
12.93 + 0.15b |
25.1 + 0.86c |
|
4
PPI |
477 |
27.35 + 0.25e |
66.5 + 0.26e |
7.4 + 0.07c |
64.83 + 0.29e |
59.8
± 0.23d |
13.9 +
0.10d |
2.00 + 0.05c |
25.9+ 0.33e |
12.98 + 0.12b |
26.0 + 1.12c |
|
Sex |
|
*** |
*** |
*** |
** |
*** |
*** |
*** |
*** |
* |
|
|
Female |
823 |
20.87 + 0.15 |
59.5 + 0.16 |
6.5 + 0.05 |
58.9 + 0.18 |
55.4
± 0.14 |
12.4
± 0.06 |
2.15
± 0.03 |
15.4
± 0.21 |
12.5
± 0.07 |
NA |
|
Male |
68 |
26.44 + 0.39 |
64.8 + 0.42 |
7.5 + 0.12 |
63.1 + 0.46 |
59.6
± 0.36 |
13.3
± 0.15 |
2.51
± 0.08 |
26.3
± 0.52 |
13.0
± 0.19 |
NA |
|
PS |
|
*** |
NS |
*** |
NS |
NS |
NS |
** |
** |
NS |
NS |
|
Agropastoral |
281 |
24.12 ± 0.26 |
61.9 ± 0.28 |
6.7 ± 0.08 |
61.1 ± 0.31 |
57.5 ± 0.24 |
12.9 + 0.10 |
2.46 + 0.06 |
20.3 +
0.29 |
12.7 +
0.12 |
24.0 +
0.66 |
|
Pastoral |
610 |
23.19 ± 0.22 |
62.6 ± 0.24 |
7.3 ± 0.07 |
60.8 ± 0.26 |
57.6 ± 0.20 |
12.8 + 0.09 |
2.21 + 0.05 |
21.3 +
0.35b |
12.7 +
0.11 |
22.6 +
0.46 |
|
Sex*age |
|
*** |
*** |
NS |
*** |
*** |
*** |
*** |
*** |
NS |
|
|
Femal 0PPI |
105 |
16.8±0.30a |
54.5±0.32a |
5.9±0.0.10a |
54.6±0.36a |
52.4±0.28a |
11.0±0.12a |
2.46±0.07a |
10.7±0.38a |
11.7±0.14 |
NA |
|
Femal 1PPI |
75 |
19.1±0.35b |
58.1±0.38b |
6.5±0.12b |
58.1±0.42b |
54.4±0.33b |
12.1±0.14b |
2.31±0.08a |
13.1±0.44b |
12.6±0.17 |
NA |
|
Femal 2PPI |
50 |
20.5±0.43c |
60.4±0.47c |
7.1±0.14c |
57.9±0.52b |
55.7±0.41c |
12.6±0.17c |
1.96±0.09b |
16.2±0.54c |
12.7±0.21 |
NA |
|
Femal 3PPI |
128 |
23.0±0.27d |
62.4±0.29d |
6.9±0.09c |
61.2±0.32c |
57.4±0.25d |
12.9±0.11c |
2.09±0.06b |
17.1±0.33c |
12.7±0.13 |
NA |
|
Femal 4PPI |
465 |
24.3±0.14e |
63.9±0.15e |
7.0±0.05c |
62.6±0.17d |
57.6±0.13d |
13.4±0.06d |
1.72±0.03e |
20.0±0.18d |
12.8±0.07 |
NA |
|
Male 0PPI |
22 |
18.7±0.65bf |
55.9±0.71af |
6.4±0.21bd |
55.0±0.78ae |
54.1±0.61be |
11.0±0.26ae |
2.43±0.14abf |
14.4±0.79bce |
12.3±0.32 |
NA |
|
Male 1PPI |
12 |
20.7±0.89bcf |
60.8±0.96cdg |
7.4±0.29ce |
59.3±1.05bcf |
56.8±0.83cdf |
12.6±0.35bcf |
2.5±0.19abf |
19.4±1.07df |
13.6±0.45 |
NA |
|
Male 2PPI |
8 |
28.6±1.08g |
65.5±1.17eh |
7.6±0.36cef |
64.6±1.29dg |
61.0±1.02g |
13.5±0.43cdfg |
2.63±0.24abf |
25.8±1.32g |
13.0±0.71 |
NA |
|
Male 3PPI |
14 |
31.7±0.82h |
71.0±0.89i |
8.3±0.27f |
68.2±0.98h |
63.2±0.77gh |
13.9±0.33dg |
2.50±0.18abf |
37.1±1.03h |
13.0±0.38 |
NA |
|
Male 4 PPI |
12 |
34.4±0.89i |
73.9±0.96j |
8.3±0.29f |
70.8±1.05h |
65.0±0.83h |
16.3±0.35h |
2.58±0.19abf |
37.9±1.07h |
12.8±0.41 |
NA |
a,b,c,d,e,f,g,h,i
means on the same column with different superscripts, within the
specified class variable, are significantly different (p <0.05); Ns =
non-significant; *P< 0.05; ** P< 0.01; CG = Chest Girth; CW = Chest
width; BL= Body length; HW = height at Wither; PW = Pelvic Width; BCS = Body
Condition Score; HL = Horn Length; EL = Ear Length; SC = Scrotal Circumference;
0PPI = 0 Pair of Permanent Incisors, 1PPI =1 Pair of permanent Incisors; 2 PPI
= 2Pairs of Permanent Incisors; 3PPI = 3 Pairs of Permanent Incisors; 4PPI = 4
Pairs of Permanent Incisors; NA = Not Applicable.
Sex effect: In all traits considered, males
showed significantly (P<0.001, P<0.05) higher measurements than female
except ear length (EL) (P>0.05). The effect of sex in body weight and linear
measurements in favor of males was in consonance with other works (Leng et al.,
2010; Semakula
et at.,
2010; Grum et al, 2012; Tsegaye
et al, 2013). Body weight and linear measurements revealed
in this study both for mature males and females were similar to the observation
of Nigatu (1994) for the same breed.
Age effects: Age has significant (P <
0.01) effect on body weight and linear measurements and there were consistent
increases in the traits considered as the animals aged (Table 1). This is
expected since the size and shape of the animal increase as the animal advance
in age. The variation in weight and body
measurements sharply
reduced at later stages (e.g. 3PPI and 4PPI). This may be attributed to the
attainment of the mature weight in which growth is at decreasing rate (Hifzan et al, 2015). Steven et al (2019) also stated that
at maturity, linear body measurements are essentially a constant, thereby
reflecting heritable size of the skeleton.
Interaction effect: The sex by age
interaction has significant effect (p<0.01) for weight and body measurements
(Table 1). The interaction effect of sex and age was also evident in other
studies (Workneh, 1992; Tsegaye
et al, 2013). In both sexes, body weight and measurements increased as age of the animal advances. In all
parameters except BCS, females showed wider range of variation in measurements
between age class 0PPI and 1PPI and a narrow variation was observed at later
age groups. While male goats’ shows accelerated growth through 0PPI to 2PPI
years and slower growth rate was observed post age group of 2PPI. A similar
growth trend was reported in other studies (Leng et
al., 2010; Grum
et al, 2012).
The growth
trend in this study may suggest that the age between one and three years may be
the age in which the animal shows the fastest growth rate. This is expected
since animals, under normal conditions, grow fast when younger but grow slowly
when they reach maturity (Hifzan et al 2015; Steven
et al, 2019).
The live weight
of males and females at age 2PPI were about 83.1% and 84.4% of that at age
group 4PPI, respectively. This can suggests that, farmers could sell goats
after age group 2PPI. However such decision cannot be solely made on biological
parameters and the availability of feed and other cost associated with their
husbandry would certainly play an important role in making such decision.
The correlation between body weight with body
measurements in the pooled data was positive and significant (P< 0.01). The
relationship of body weight over other variables with respect to sex and age
category was presented in Table 2. Within females, body weight shows a positive
and significant (P < 0.01, P < 0.05) relationship with body measurements
across all age group. Chest girth (r=0.84) and body
length (r=0.70) showed positive and strong association (P< 0.01) with body
weight.
In the pooled data (0-4PPI) set of males, CG,
BL, HW, PW, SC and HL show strong and positive correlation (r<0.01) with
body weight. Negative and non-significant association of EL and body weight was
found for the pooled data of 3PPI – 4PPI. In this study, scrotal circumference
showed significant association (P<0.01) with live body weight in all age
categories. Therefore, selection for scrotal circumference would lead to males
with high potential for sperm production while indirectly improving body
weight.
The pooled data of males showed higher ‘r’
value than pooled data of female for all variables except EL (r=0.07). This
signifies the stronger association of body weight with linear measurements in
male than female. Therefore, a separate regression equation for each sex would
be preferable to estimation body weight from independent variables.
The higher
association between live body weight and body measurements demonstrated the
possibility of using simple body measurements that can be carried out in the
field to predict body weight. For both males and females in all age categories,
chest girth consistently gave higher correlation with body weight as compared
with other body measurements. This is also evident in several studies (Fajemilehin and Salako, 2008;
Leng et al., 2010; Grum et al, 2012; Tsegaye et
al, 2013).
Table
2 Coefficients of correlation between
body weight and body measurements within age and sex groups
|
Trait |
|
Age group |
Overall |
|||||||||
|
|
Male |
|
Female |
|||||||||
|
|
0-1PPI |
2-4 PPI |
0-4PPI |
|
0PPI |
1PPI |
2PPI |
3PPI |
4PPI |
0-4PPI |
||
|
CG |
r |
0.69** |
0.81** |
0.94** |
|
0.75** |
0.76** |
0.66** |
0.67** |
0.71** |
0.84** |
0.86** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
CW |
r |
0.48** |
0.16Ns |
0.58** |
|
0.46** |
0.22NS |
0.09NS |
0.10NS |
0.23** |
0.37** |
0.42** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
BL |
r |
0.59** |
0.62** |
0.88** |
|
0.66** |
0.42** |
0.50** |
0.56** |
0.47** |
0.70** |
0.73** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
HW |
r |
0.66** |
0.51** |
0.87** |
|
0.52** |
0.49** |
0.57** |
0.48** |
0.34** |
0.61** |
0.67** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
PW |
r |
0.57** |
0.61** |
0.83** |
|
0.45** |
0.53** |
0.47** |
0.34** |
0.43** |
0.62** |
0.65** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
BCS |
r |
0.33NS |
0.45** |
0.27* |
|
0.30** |
0.57** |
0.27NS |
0.36** |
0.40** |
0.04Ns |
0.04** |
|
|
N |
34 |
34 |
68 |
|
105 |
75 |
50 |
128 |
465 |
823 |
891 |
|
HL |
r |
0.73Ns |
0.61NS |
0.91** |
|
0.72** |
0.33** |
0.47** |
0.52** |
0.29** |
0.64** |
0.72** |
|
|
N |
34 |
33 |
67 |
|
96 |
73 |
48 |
127 |
439 |
783 |
850 |
|
EL |
r |
0.40* |
-0.3Ns |
0.07NS |
|
0.27** |
0.09NS |
0.31* |
0.20* |
0.02Ns |
0.21** |
0.20** |
|
|
N |
32 |
32 |
64 |
|
102 |
72 |
47 |
123 |
443 |
787 |
851 |
|
SC |
r |
0.66** |
0.53** |
0.73** |
|
NA |
NA |
NA |
NA |
NA |
NA |
0.73** |
|
|
N |
34 |
27 |
61 |
|
NA |
NA |
NA |
NA |
NA |
NA |
61 |
r = coefficient of
correlation; N= Number of observation; NS = non-significant; *P< 0.05; **
P< 0.01; CG = Chest Girth; CW = Chest width; BL= Body length; HW = height
Wither; PW = Pelvic Width; BCS = Body Condition Score; HL = Horn Length; EL =
Ear Length; SC = Scrotal Circumference; 0PPI = 0 Pair of Permanent Incisors,
1PPI =1 Pair of Permanent Incisors; 2PPI = 2 Pairs of Permanent Incisors; 3PPI
= 3 Pairs of Permanent Incisors; 4PPI = 4 Pairs of Permanent Incisors, NA =
Non-applicable.
Summary of
multiple linear regression analysis and generated models for predicting body
weight from body measurements for each sex at different age categories were
presented in Table 3. In the entire model, chest girth was the single most
important variable to produce the largest R2. For the pooled data of
females, chest girth (CG), body length (BL), height at wither (HW), pelvic
width (PW) and body condition score (BCS) are the best multiple regressor (R2 = 0.78 and Cp
= 5.9) to estimate body weight. For the pooled data of male, four alternative
model was identified with a slightly varied R2 (0.89 – 0.92) and
Mallow’s Cp ranging from 22.2–4.8. Chest girth, BL,
HW and BCS are the best regressor variables to
predict body weight of male. Nevertheless, the remaining equations can also be
used with reduced precision under different circumstance (time, cost and ease
of application).
Under smallholder situation where there is
limited access to weighting scale, the pooled data models (Yf
= -23 + 0.73CG + 0.22BL and Ym = -30.2 + 0.87CG) can
easily be used to estimate live weight of female and male Afar goat breed
respectively for selection, mating and live weight based pricing purpose.
The pooled
data of male shows higher coefficient of determination than the pooled data of
female. A similar situation was also reported in other studies (Grum et al, 2012; Tsegaye et al,
2013). Therefore, using a separate equation for each sex is feasible and can
substantially increase precision to estimation body weight.
Table
3: Prediction equations for body weight
at different sex and age groups
|
Dentition |
Equations |
Intercept |
β1 |
β2 |
β3 |
β4 |
β5 |
β6 |
R2 |
|
Cp |
|
Female 0PPI |
CG |
-19.2 |
0.66 |
|
|
|
|
|
0.56 |
0 |
38.7 |
|
CG+BL |
-23.7 |
0.49 |
0.25 |
|
|
|
|
0.64 |
0.07 |
16.9 |
|
|
CG+BL+BCS |
-25.3 |
0.49 |
0.23 |
1.10 |
|
|
|
0.69 |
0.05 |
3.04 |
|
|
1PPI |
CG |
-24.05 |
0.74 |
|
|
|
|
|
0.58 |
0 |
45.4 |
|
CG+BCS |
-21.50 |
0.64 |
1.5 |
|
|
|
|
0.73 |
0.14 |
7.4 |
|
|
CG+BL+BCS |
-25.0 |
0.58 |
0.12 |
1.5 |
|
|
|
0.74 |
0.02 |
5.0 |
|
|
2PPI |
CG |
-19.1 |
0.66 |
|
|
|
|
|
0.44 |
0 |
25.4 |
|
CG+HW |
-35.7 |
0.53 |
0.44 |
|
|
|
|
0.58 |
0.14 |
9.7 |
|
|
CG+BL+HW |
-42.3 |
0.42 |
0.23 |
0.43 |
|
|
|
0.62 |
0.05 |
5.8 |
|
|
CG+BL+HW+PW |
-43.2 |
0.34 |
0.23 |
0.42 |
0.53 |
|
|
0.64 |
0.03 |
3.5 |
|
|
3PPI |
CG |
-19.7 |
0.68 |
|
|
|
|
|
0.45 |
0 |
46.0 |
|
CG+BCS |
-19.6 |
0.64 |
1.2 |
|
|
|
|
0.52 |
0.07 |
26 |
|
|
CG+BL+BCS |
-25.1 |
0.49 |
0.25 |
1.2 |
|
|
|
0.58 |
0.06 |
9.1 |
|
|
CG+BL+HW+BCS |
-29.8 |
0.40 |
0.23 |
0.19 |
1.3 |
|
|
0.60 |
0.02 |
4.2 |
|
|
4PPI |
CG |
-16.5 |
0.64 |
|
|
|
|
|
0.51 |
0.0 |
159.7 |
|
CG+BL |
-15.9 |
0.59 |
1.4 |
|
|
|
|
0.59 |
0.08 |
59.6 |
|
|
CG+BL+BCS |
-22.6 |
0.53 |
0.18 |
1.3 |
|
|
|
0.625 |
0.04 |
16.2 |
|
|
CG+BL+PW+BCS |
-23.1 |
0.50 |
0.16 |
0.26 |
1.3 |
|
|
0.632 |
0.008 |
8.5 |
|
|
CG+BL+HW+PW+BCS |
-25.7 |
0.48 |
0.15 |
0.08 |
0.25 |
1.3 |
|
0.636 |
0.004 |
5.4 |
|
|
0-4PPI |
CG |
-22.9 |
0.73 |
|
|
|
|
|
0.71 |
0 |
262.7 |
|
CG+BL |
-27.4 |
0.59 |
0.22 |
|
|
|
|
0.74 |
0.03 |
135.6 |
|
|
CG+BL+BCS |
-30.7 |
0.60 |
0.23 |
0.93 |
|
|
|
0.769 |
0.03 |
36.0 |
|
|
CG+BL+HW+BCS |
-24.34 |
0.36 |
0.22 |
0.14 |
0.37 |
|
|
0.776 |
0.003 |
13.8 |
|
|
CG+BL+HW+PW+BCS |
-33.5 |
0.53 |
0.20 |
0.12 |
0.20 |
0.96 |
|
0.778 |
0.002 |
5.9 |
|
|
Male (0- 4PPI) |
CG |
-30.2 |
0.87 |
|
|
|
|
|
0.89 |
0 |
22.2 |
|
CG+BCS |
-33.3 |
0.85 |
1.71 |
|
|
|
|
0.907 |
0.02 |
11.8 |
|
|
CG+
HW + BCS |
-38.4 |
0.72 |
0.24 |
1.6 |
|
|
|
0.914 |
0.008 |
7.8 |
|
|
CG+BL+HW+BCS |
-39.8 |
0.56 |
0.18 |
0.23 |
1.7 |
|
|
0.921 |
0.006 |
4.8 |
BL=
Body length; CG = Chest Girth; CW = Chest width WH = Wither height; PW = Pelvic
Width; SC = Scrotal circumference; SL = Scrotal Length; BC = Body Condition
Score; 0PPI = 0 Pair of Permanent Incisors, 1PPI =1 Pair of Permanent Incisors;
2 PPI = 2Pairs of Permanent Incisors; 3PPI = 3 Pairs of Permanent Incisors;
4PPI = 4 Pairs of Permanent Incisors
Most of the
linear parameters depicted positive and highly significant (P<0.01)
correlation with body weight. The regression analyses showed that body weight
could be predicted from chest girth (CG) and body length (BL). The simplified
model (weight of female = -23 + 0.73CG + 0.22BL and weight of male = -30.2 +
0.87CG) can be used to estimate body weight of female and male Afar goat breed
with 74% and 89% coefficient of determination (R2) respectively.
This will assist pastorals in making good judgment for breeding, feeding,
veterinary service and marketing in area where weighting scales are rarely
available.
The authors
state that there is no conflict of interest with any financial, personal, or
other relationships with other people or organizations in the manuscript.
The authors
are grateful to Afar Pastoral and Agro-pastoral Research Institute (APARI) for
financial support of this research. The authors also like to thank Wolkite University for coordination of the research.
CSA (Central Statistical
Agency). (2019). Projected
Population of Ethiopia 2011 EC (2019) for all Regions at Woreda
Level from. Addis Ababa, Ethiopia, 2019.
Fajemilehin, O. K. and. Salako, A. E. (2008). Body measurement
characteristics of the West African Dwarf (WAD) Goat in deciduous forest zone
of Southwestern Nigeria. African Journal of Biotechnology
7(14):2521-2526, 18 July, 2008.
FARM-Africa. (1996). Goat types of Ethiopia and
Eritrea. Physical description and management systems.
Published jointly by FARM-Africa, London, UK, and ILRI
(International Livestock Research Institute), Nairobi, Kenya. 76p.
Gebremedhin, B., Hoekstra,
D., Tegegne, A., Shiferaw, K. and Bogale, A. (2015). Factors determining household market participation in small ruminant
production in the highlands of Ethiopia. LIVES Working Paper 2. Nairobi,
Kenya: International Livestock Research Institute.
Girma Abebe. (2009). Body
Condition Scoring of Sheep and Goats. A. a. Merkel, (ed). Ethiopia Sheep and Goat Productivity
Improvement Program USAID ,
Technical Bulletin No.8.
Girma Abebe and Alemu
Yami. (2008). Sheep and goat management system. In: Alemu Yami and Merkel, R.C (Eds), Sheep and Goat
Production Handbook for Ethiopia. Pp 33 – 57. Ethiopia Sheep and Goat productivity Improvement Program (ESGPIP).
Grum Gebreyesus, Aynalem Haile and Tadelle Dessie, (2012). Body weight
prediction equations from different linear measurements in the short-eared somali goat population of Eastern
Ethiopia. Research J of Animal Sciences, 6: 90-93.DOI: 10.3923/rjnasci.2012.90.93
Haile A, Gizaw S, Getachew T, Mueller J, Amer P, Rekik M,
and Rischkowsky B. (2019) Community-based breeding programmes are a viable solution for Ethiopian small
ruminant genetic improvement but require public and private investments. JAnim Breed
Genet. 2019;136:319–328. https://doi.org/10.1111/jbg.12401
Hifzan, R. M., Idris, I., & Yaakub, H.
(2015). Growth Pattern for Body Weight, Height at Withers and Body Length
of Kalahari Red Goats. Pakistan journal of biological sciences: PJBS,
18(4), 200–203. https://doi.org/10.3923/pjbs.2015.200.203
Laird, S. (2002). Biodiversity
and traditional knowledge: Equitable partnerships in practice. Earthscan
Publications, London.
Leng Jing, Zhu Ren-Jun, Zhao Guo-Rong, Yang
Qing-Ran and Mao Hua-Ming. (2010). Quantitative
and Qualitative Body Traits of Longling Yellow Goats
in China. Agricultural Sciences in
China. 9(3): 408-415
Mallows, C. L.
(1973). Some
Comments on Cp. Technometrics,
Vol. 15, No. 4. Nov., 1973, pp. 661-675. Taylor &
Francis, Ltd. https://doi.org/10.2307/1267380
McGregor,
B. (2007). Assessment skills for goat meat marketing,
Agriculture Note. Victoria: Department of primary industry.
Misbah, F., Belay, B. and Haile, A. (2015). Participatory definition of trait preference and pastorals’
indigenous knowledge on goat breeding strategy around Aysaita
district, Ethiopia. LRRD. Volume
27, Article #158. http://www.lrrd.org/lrrd27/8/misb27158.html.
Mueller, J.P., B. Rischkowsky, A. Haile, J. Philipsson,
O. Mwai, B. Besbes, A.
Valle Zárate, M. Tibbo, T, Mirkena, G. Duguma, J. Sölkner & M. Wurzinger.
(2015). Community-based livestock breeding programmes:
essentials and examples. J. Anim. Breed. Genet.132, 155–168.
Nigatu Alemayehu.
(1994). Characterization of indigenous goat types of Eritrea,
Northern and Western Ethiopia. An MSc Thesis presented to the School of Alemaya University of Agriculture. Alemaya,
Ethiopia. 136pp
Peters, K J. (1985).
Principles of evaluating goat populations in tropical and
subtropical environments. Proc. 36th Annual Meeting
of EAAP. Kallithen, Greece
R
Core Team (2021).
R: A language and environment for statistical computing. R
Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/.
Rege J.E.O. (2003). Livestock Breeds in traditional animal genetic
resources management. pp 117-139. In: CIP-UPWARD.
Conservation and sustainable use of agro-biodiversity: A source book. Los Bonas, Laguna, the Philippines.
Semakula,
Jimmy; David, Mutetikka; Kugonza,
Donald and Mpairwe, Denis. (2010). Variability
in body morphometric measurements and their application in predicting live body
weight of Mubende and Small East African goat breeds
in Uganda. Middle-East Journal of Scientific Research.
5. 98-105.
Steven M. Lonergan,
David G. Topel, Dennis N. Marple.
(2019). Growth Curves and Growth Patterns. In Steven
M. Lonergan, David G. Topel,
Dennis N. Marple (Eds), The Science of Animal Growth and Meat Technology (2nd
Ed). Academic Press, 2019, Pages 71-109, ISBN 9780128152775. https://doi.org/10.1016/B978-0-12-815277-5.00006-8.
Tsegaye, Dereje & Belay, Berhanu &
Haile, Aynalem. (2013). Linear
body measurements as predictor of body weight in hararghe
highland goats under farmers environment: Ethiopia. Global Veterinaria. 11. 649-656.
10.5829/idosi.gv.2013.11.5.76135.
Workneh Ayalew. (1992). Preliminary survey of indigenous goat types and goat
husbandry practices in southern Ethiopia. M.Sc.
Thesis, Alemaya University of Agriculture. Alemaya, Ethiopia. 156p
Zewdie B.
and Welday K. (2015). Reproductive
Performance and Breeding Strategies for Genetic Improvement of Goat in
Ethiopia: A Review. Greener Journal of Agricultural Sciences.
Vol. 5 (1), pp. 023-033, February 2015. DOI: http://doi.org/10.15580/GJAS.2015.1.080614317.
Appendix Table 1 List of quantitative traits and method
of measurementsa
|
Parameter |
Units |
Descriptions |
|
Body
weight |
Kg |
Taken
early in the morning using 50 kg spring balance |
|
Body
length |
cm |
The horizontal
distance from the point of shoulder to the pin bone to the nearest
centimeter. |
|
Chest
girth |
cm |
The circumferential
measure taken around the chest just behind the front legs and withers to the
nearest 0.5cm. |
|
Height
at wither |
cm |
The height from the
bottom of the front foot to the highest point of the shoulder between the
withers to the nearest centimeter. |
|
Chest
width |
cm |
The
width of the chest between the briskets to the nearest centimeter. |
|
Pelvic
width |
cm |
The distance
between the pelvic bones, across dorsum to the nearest centimeter. |
|
Ear
length |
cm |
The length of the
ear on its exterior side from its root at the poll to the tip to the nearest
centimeter. |
|
Scrotal
circumference |
cm |
The circumference
of the testicles at the widest part to the nearest centimeter. |
|
Horn
length |
cm |
Length of the horn
on its exterior side from its root at the poll to the tip. |
aAdapted from Girma and Alemu (2008)
Appendix Table 2
Scales for body condition scoring1
|
Score |
Features |
Condition |
||
|
Spinous and
transverse process of Lumbar region |
Eye muscle area |
Rib cage |
||
|
1 |
The spinous processes are prominent and sharp. The transverse
process are also sharp, the fingers pass easily under the ends, and it is
possible to feel between each process. |
The eye
muscle areas are shallow with no fat cover. |
Ribs
are clearly Visible |
Very
thin |
|
2 |
The spinous processes feel prominent but smooth, and
individual processes can be felt only as fine corrugations. The transverse
processes are smooth and rounded, and it is possible to pass the fingers
under the ends with a little pressure. |
The eye
muscle areas are of moderate depth, but have little fat cover. |
Some
ribs can be seen. There is a small amount of fat cover. Ribs are still felt. |
Thin |
|
3 |
The spinous processes are detected only as small elevations;
they are smooth and rounded and individual bones can be felt only with
pressure. The transverse processes are smooth and well covered, and firm
pressure is required to feel over the ends. |
The eye
muscle areas are fully covered to end of spinal processes. Feels rounded and
have a moderate degree of fat cover. |
Ribs
are barely seen; an even layer of fat covers them. Spaces between ribs are
felt using pressure. |
Moderate
|
|
4 |
The spinous processes can just be detected with pressure as a
hard line between the fat covered eye muscle areas. The ends of the
transverse processes cannot be felt. |
The eye
muscle areas are full, and have a thick covering of fat. |
Ribs
are not seen |
Fat |
|
5 |
The spinous processes can't be detected even with firm
pressure, and there is a depression between the layers of fat in the position
where the spinous processes would normally be felt. The
transverse processes cannot be detected. |
The eye
muscle areas are very full with thick fat cover. There may be large deposits
of fat over the rump and tail. |
Ribs
are no visible and are covered with excessive fat. |
Very
fat |
1Adapted from McGregor
(2007) and
Girma (2009)
Cite this Article:
Misbah, F; Derese, M; Haiyre, G (2023).
Prediction of Afar Goat Breed Live Body Weight to Facilitate Breed
Improvement and Husbandry Practice. Greener
Journal of Agricultural Sciences, 13(4): 217-226. |