J. Bio. Env. Sci. 2016 Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220-6663 (Print) 2222-3045 (Online) Vol. 8, No. 6, p. 67-73, 2016 http://www.innspub.net RESEARCH PAPER
Analysis of the non-genetic factors affecting the growth traits of Balouchi sheep Reza Tohidi1*, Arash Javanmard2 , Vahid Shamsabadi1 1
Dept. of Animal Science, University of Torbat-e-Jam, Iran
Dept. of Animal Science, University of Tabriz, Tabriz, Iran Article published on June 11, 2016
Key words: Balouchi sheep, Growth traits, Environmental factors.
Abstract A study was conducted to evaluate the effects of non-genetic factors on the growth behavior of Balouchi sheep breed. The data of growth traits, birth weight (BW), weaning weight (WW), weight at 6, 9 and 12 months of age (W6, W9 and W12, respectively) were taken from 1400 lambs belonging to historical data from Abbasabad Sheep Breeding Station located at the North-east of Iran during a period of five years. Statistical analyses were performed using a general linear model including non-genetic factors: lamb sex, birth year and litter size as main effects, the lambâ€™s age when weighed as covariable, and the interactions between these factors. Results showed that all traits were significantly (P < 0.001) affected by all factors. However, the interaction between sex and litter size was not significant for BW, WW and W6. Environmental factors have very important roles in the development and growth of Balouchi sheep at different ages. Therefore, a correction is necessary to increase the accuracy of direct selection on lamb weight at different growth stages. *Corresponding
Author: Reza Tohidi ď€Ş firstname.lastname@example.org
67 | Tohidi et al.
J. Bio. Env. Sci. 2016 Introduction
North-east of Iran during 2005-2009 were utilized to
There were about 50 million heads of sheep in 2013 in
estimate the effect of environmental factors affecting
Iran (FAO, 2016). The Balouchi breed is one of the
BW, WW, W6, W9, and W12. The animals were raised
famous meat-wool sheep breeds in this country. This
in a closed system and fed with alfalfa, barley and
breed is fat tailed and well adapted to harsh
straw. Sheep were supplemented in the last month of
environmental condition of eastern and north-eastern
gestation and during lactation (usually barley), and
area of Iran (Tahmoorespur and Sheikhloo, 2011).
births occurred mainly in April and May. Lambs were
There are various production traits of this breed
left with dams until age 90 days, from this age they
were kept to fatten until reaching slaughter age.
improvement of economic traits. However, growth performances are preferred traits to improve due to
Data and analyses
low economic value of wool compared to meat
The data file contained information on individuals,
production. The growth demonstrated as a change in
sire and dam identification code, sex, litter size, birth
volume, size or shape with the passing of time is a
date, date of weighing and measure of body weight.
very important characteristic of living organisms,
The data were analyzed to estimate the effect of year
especially in meat sheep (Lupi et al., 2015). Diversity
of birth, litter size and sex of lamb born on the lamb
in performance traits could be due to several genetic
growth. The mathematical model assumed for the
and environmental factors. Any selection program
Least-Squares Analysis was:
should be designed based on the genetic and environmental effects on the objective traits (Yazdi et
Yijklm = + Si + Aj + Lk + (SA)ij + b(Age – Age) + ijklm
al., 1999). Non-genetic factors must be corrected before starting genetic analysis. Even when an
where Yijklm is the weight of a lamb; is the overall
attempt is made to provide a uniform environment,
mean; Si is the sex of lamb; Aj is the year of birth of a
there are still unknown environmental differences
lamb; Lk is litter size; (SA)ij is the interaction between
between animals, known as residual error. An
sex and year of birth; b is regression coefficient, Age is
adjustment should be made for environmental and
age of lamb at weighing time, ijklm is residual error. A
physiological sources of variation such as age, sex,
statistical analysis using the univariate general linear
birth type or litter size, years, seasons and such other
model from the statistical package Minitab v.16 was
environmental variables that can be evaluated (Babar
used to analyze the effect of the fixed factors and
et al., 2004).The effect of non-genetic factors on
interaction between them on the total variance of the
growth performance in sheep has been investigated in
several studies. These factors in different areas have their own specific effects regarding the environmental
The lamb’s age at weighing time was used as covariate
characteristics of related areas (Gbangboche et al.,
to correct the record of WW, W6, W9 and W12.
2006; Momoh et al., 2013). Therefore, the present
Comparison of means was performed by Tukey test,
study was carried out to investigate the effect of sex of
setting P < 0.05 to identify significant differences
lamb, year of birth and litter size on body weight of
Balouchi lambs at different ages. Results and discussion Materials and methods
The data were used in the present study belonging to
Animals and location of study area
Abbasabad sheep breeding station that Balouchi
The data on 1400 lambs born from 438 Balouchi ewes
breed is mainly kept over there. This sheep is a dual
sired by 61 rams kept at the Abbasabad sheep
purpose breed, however, as wool is not a valuable
breeding station located at a semi-arid area in the
product, meat is a more important trait in this breed.
68 | Tohidi et al.
J. Bio. Env. Sci. 2016 As shown in Fig. 1, there was not such a big variation
The effects of sex, birth year and litter size are shown
for BW and WW among different years, however, it
in the Tables one to three, respectively. All non-
genetic factors that have been investigated in this study significantly influenced on lamb weights in all
Two reasons are supposed for this result, first, the
ages (P ď€ź 0.001). Male animals were heavier than
selection program is not suitable and second,
females as shown in Table 1.
environmental factors influence the traits. Table 1. Least square means (LSM) and standard error (SE) of lambs live weights according to sex of lambs. Trait BW
Sex1 M F WW M F W6 M F W9 M F W12 M F 1 Sex of lambs; M: male, F: female
N2 588 534 222 212 343 287 213 148 194 169
LSM3 3.671a 3.440b 21.220a 18.890b 33.020a 29.630b 41.420a 35.800b 48.130a 41.680b
SE 0.151 0.152 1.001 1.000 1.356 1.360 1.312 1.342 1.148 1.170
2 Number of records 3 Column with different superscripts within subclass indicate significant differences (P < 0.001). Table 2. Least square means (LSM) and standard error (SE) of lambs live weights according to year of birth of lambs. Trait BW
Birth year 2005 2006 2007 2008 2009 2005 2006 2007 2005 2006 2007 2008 2005 2006 2007 2005 2006 2007
N1 176 209 239 183 315 151 188 95 136 176 159 159 103 129 129 114 90 159
LSM2 3.410b 3.638a 3.526ab 3.678a 3.526ab 17.190b 21.070a 21.900a 30.980b 32.810a 28.110c 33.400a 37.470b 39.070a 39.300a 46.650a 43.940b 44.130b
SE 0.156 0.155 0.156 0.158 0.154 1.030 1.024 1.051 1.389 1.378 1.409 1.398 1.351 1.353 1.346 1.174 1.211 1.175
1 Number of records 2 Column with different superscripts within subclass indicate significant differences (P < 0.001) This fact has been reported in the other studies
et al., 2013; Lupi et al., 2015). Differences in
(McManus et al., 2003; Babar et al., 2004; Macedo
physiological functions in both sexes cause such a
and Arredondo, 2008; Baneh and Hafezian, 2009;
tendency in body weight. The nature of testosterone, a
Ulutas et al., 2010; Gbangboche et al., 2011; Momoh
steroid hormone whose anabolic effects act as growth
69 | Tohidi et al.
J. Bio. Env. Sci. 2016 promoter, attributes in postnatal growth in males
climate conditions (precipitation, humidity and
(Lupi et al., 2015).
management as well as some environmental effects The variation in lamb weights at different ages
on the ewes during pregnancy.
observed in different years (Table 2) may be due to Table 3. Least square means (LSM) and standard error (SE) of lambs live weights according to litter size. Trait BW
Litter size 1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 1 2 3
N1 565 531 18 2 5 243 182 10 2 353 264 6 2 225 133 2 209 150 2
LSM2 4.646a 3.948b 3.341c 3.044cd 2.373d 23.780a 20.080b 15.200c 15.170c 34.050a 30.630b 27.440bc 25.760c 37.870a 35.350b 37.120a 44.220a 41.640b 40.900b
SE 0.029 0.030 0.160 0.482 0.305 0.262 0.281 1.564 2.701 0.283 0.330 1.672 3.754 0.287 0.384 3.011 0.276 0.335 2.274
1 Number of records 2 Column with different superscripts within subclass indicate significant differences (P < 0.001). Table 4. Estimates of phenotypic correlation (below diagonal) and corresponded Pearson correlation P-value (above diagonal) between lambs live weights. Trait
The management includes farmer manager, his ability
Litter size (single or multiple) had significant effects
to supervise the staff, availability of financial
on living weight at different ages of lambs, single born
resources and selection strategies. Climate and
lambs were heavier than multiple born lambs (Table
environmental changes affect the quality and quantity
3). This result is according to the earlier studies
of pasture forages, which affect the provision of food
(Dimsoski et al., 1999; Rodríguez et al., 1999;
(Baneh and Hafezian, 2009; Momoh et al., 2013).
Hernández, 2004; Hinojosa-Cuéllar et al., 2012;
Adequately fed ewes are expected to produce heavy
Gavojdian et al., 2013). This could be due to
competition for nutrient and uterine space and the limited capacity of ewes to provide more nourishment
70 | Tohidi et al.
J. Bio. Env. Sci. 2016 for the development of multiples fetuses and more
after weaning, that are higher than those of single
milk for lambs (Gbangboche et al., 2006; Momoh et
birth lambs. Therefore, there are differences between
al., 2013). However, the multiple born lambs may
breeds in term of the effect of litter size on live
demonstrate compensatory growth after weaning.
weight. In addition, the interaction between sex and
There was no variation in weaning weights among
litter size was significant (P ď€ź 0.01) for w9 and w12
lambs from different birth types (Quesada et al.,
that shows it should be considered in genetic
2002) and also, GonzĂĄlez et al. (2002) concluded that
lambs from multiple births reach daily weight gains
Fig. 1. Least square means of BW and W6 according to year of birth of lambs. Table 4 presents the coefficients of phenotypic
weight of Balouchi sheep from birth to 12 months of
correlation between body weights and corresponded
Pearson correlation P-value. Although, all correlation coefficients are significant, the correlation between
A breeding program needs to adjust
WW, W6, W9 and W12 are higher than correlation
according to non-genetic effects to estimate breeding
between BW and the other traits. Similar results were
values of animals accurately. Sex of lamb, year of
observed in previous studies for the Sabi sheep of
birth and litter size influenced body weight of
Balouchi lambs. Hence, the effect of these factors
(Matika et al., 2001; Rashidi, 2013; Vatankhah, 2013,
should be considered in mixed model approaches to
respectively). Phenotypic correlation between two
find pure genetic values of animals.
traits includes both the genetic and environmental correlations. With appropriate design, the genetic
correlation can be separated from the environmental
I would like to express my thanks to my colleagues in
correlation (Momoh, 2013). Therefore, in this study
the Sheep Breeding Station of Abbasabad, especially
the environmental correlation between WW and post-
Mr. Majid Jafari, for permission to use the data for
weaning weights may be higher than pre-weaning
weights. References Conclusion
Babar ME, Ahmad Z, Nadeem A, Yaqoob M.
The results obtained in the present study revealed
2004. Environmental factors affecting birth weight in
that environmental factors cause differences in live
Lohi sheep. Pakistan Veterinary Journal 24, 5-8.
71 | Tohidi et al.
J. Bio. Env. Sci. 2016 Baneh H, Hafezian SH.
Delgado JV. 2015. Analysis of the non-genetic
environmental factors on growth traits in Ghezel
factors affecting the growth of Segureno sheep. Italian
Journal of animal Science. 14, 3683-3691.
African Journal of Biotechnology 8, 2903-
2907. Macedo R, Arredondo V. 2008. Efecto del sexo, Dimsoski P, Tosh JJ, Clay JC, Irvin KM. 1999.
tipo de nacimiento y lactancia sobre el crecimiento de
Influence of management system onlitter size, lamb
ovinos pelibuey en manejo intensivo. Archivos de
growth, and carcass characteristics in sheep. Journal
Zootecnia. 57, 219-228.
of Animal Science 77, 1037-1043. Matika O, Van Wyk JB, Erasmus GJ, Baker FAOSTAT. 2016. faostat3.fao.org/browse/Q/QA/E.
RL. 2001. Phenotypic and genetic relationships between lamb and ewe traits for the Sabi sheep of
Gavojdian D, Sauer M., Padeanu I, Pacala N,
Zimbabwe. South African Journal of Animal Science.
Voia SO. 2013. Influence of production system, sex
and litter size on growth rates in Turcana lambs. Animal Science and Biotechnologies 46, 357-360.
McManus C, Evangelista C, Fernandes LAC, Miranda RM, Moreno-Bernal FE, Santos NR.
Gbangboche AB, Youssao AKI, Senou M,
2003. Curvas de crescimento de ovinos bergamácia
F,Michaux C, Abiola FA, Leroy PL. 2006.
Zootecnia. 32, 1207-1212.
Examination of non-genetic factors affecting the growth
Momoh OM, Rotimi EA, Dim NI. 2013. Breed
Soudanian zone at the Okpara breeding farm of
effect and non-genetic factors affecting growth
Benin. Tropical Animal Health and Production. 38,
performance of sheep in a semi-arid region of Nigeria.
Journal of Applied Biosciences. 67, 5302-5307.
González GR,Torres HG, Castillo AM. 2002.
Quesada M, McManus C, D’Araújo Couto FA.
nacimiento y el peso final en el tropic húmedo de
caracteristicas de produção e reprodução deovinos
México. Veterinaria Mexico 33, 443-453.
deslanados no Distrito Federal. Revista Brasileira Zootecnia. 31, 342-349.
Hernández JVR. 2004. Evaluación fenotípica y genotípica de los caracteres de crecimientoen el
Rashidi A. 2013. Genetic parameters estimates of
esquema de selección del ovino segureño. Degree
body weight traits in Iran-Black sheep. Journal of
Diss., Universidad de Córdoba, España.
Livestock Science and Technologies. 1, 50-56.
Rodríguez M, Huerta LN, Ventura SM, Rivero
LJ, Esparza D. 1999. Factoresque afectan el
Aranda-Ibáñez EM, González-Camacho JM.
comportamiento productive de corderos mestizos
2012. Factores que afectan el crecimiento predestete
mantenidos bajo condiciones semiintensivas de
de corderos Pelibuey en el tropic húmedo de México.
explotaciónen el tropic muy seco venezolano. Revista
Univ. Cienc. 28, 163-171.
de la Facultad de Agronomia. 16, 64-78.
Lupi TM, Nogales S, Leon JM, Cecilio B,
Sarti FM, Castelli L, Bogani D, Panella F. 2003.
72 | Tohidi et al.
J. Bio. Env. Sci. 2016 The measurement of chest girth as an alternative to
Journal of Animal and Veterinary Advances 9, 1384-
weight determination in the performance recording of
meat sheep. Italian Journal of Animal Science. 2, 123129.
Vatankhah M. 2013. Genetic analysis of ewe body weight
Tahmoorespur M, Sheikhloo M. 2011. Pedigree
regression models. Journal of Livestock Science and
analysis of the closed nucleus of Iranian Balouchi
Technologies. 1, 44-49.
sheep. Small Ruminant Research. 99, 1-6. Yazdi MH, Johansson K, Gates P, Nasholm A, Ulutas Z, Sezer M, Aksoy Y, Sirin E, SenU,
Jorjani H, Liljedahl LE. 1999. Bayesian analysis of
Kuran M, Akbas Y. 2010. The effect of birth types
birth weight and litter size in Baluchi sheepusing
on growth curve parameters of Karayaka lamb.
Gibbs sampling. Journal of Animal Science 77, 533â€“ 540.
73 | Tohidi et al.
A study was conducted to evaluate the effects of non-genetic factors on the growth behavior of Balouchi sheep breed. The data of growth trai...
Published on Jun 11, 2016
A study was conducted to evaluate the effects of non-genetic factors on the growth behavior of Balouchi sheep breed. The data of growth trai...