The Classification of Body Measurement on Syrian Hamster
(
Mesocricetus auratus
) Based on Factor Analysis and
Principal Component Analysis
R. H. Mulyono1, *, A. S. Tjakradidjaja2, L. L. Sari1, & Meliyana1
1Department of Animal Production & Technology, 2Department of Nutrition & Feed Technology,
Faculty of Animal Science, Bogor Agricultural University Jl. Agatis, Kampus IPB Dramaga, Bogor 16680, Indonesia
*e-mail: [email protected]
Abstract
Mesocritus (M.) auratus (Syrian hamster) is not only used a laboratory animal especially in medical research, but also is looked after as a pet animal. Genetic information can be obtained by studying body morphometry of Syrian hamster, and quantitative characteristics can be useful for conservation and breeding development. Body size characteristics of Syrian hamster is becoming the focus of this study. It is, therefore, this study is conducted to classify Syrian hamster into large, medium and small body sizes on the basis of factor analysis (FA) and principal component analysis (PCA). Hotelling T2-statistic showed differences in linear measurement of body surface between male and female Syrian hamsters (P<0.01). Results of FA showed that variable affecting the body size of male M. auratus in this study was body length; however, it did not influence the body size of female significantly. Body length in male hamsters, therefore, can be used as a reference in a selection program based on body size measurements that are not directly related to body weight. Body length is also found as discriminatory variable for body size, and the chest width was the discriminatory variable for body shape for both male and female. The distribution of colors that occur in each body size class indicated that M. auratus still has a variety in coat colors. Results of clustered diagram show that the crowd in body shape of male is greatly different from that of female Syrian hamsters. Classification the male and female Syrian hamster can be performed based on the value of first factor scores (SF-1) for practical purposes, as well as the body size. Both male and female Syrian hamster can be classified into large, medium and small groups, and each hamster individual data have SF-1 score and it own body score. It is concluded that classification of body size in M. auratus based on factor analysis and principal component analysis showed the same results.
Introducton
Mesocricetus (M.) auratus (Syran hamster) was the frst speces whch was used as a laboratory anmal at a unversty n Jerrusalem n 1930 (Hafez, 1970). Sanders and Sandadura (1992) reported that M. auratus was the approprate labora-tory anmal for studyng the effect of boled coffee on hypercholesterolema. Born-hop et al. (2003) also used M. auratus n observng Lumnescent Lanthande Che-late Contrast Agents for detectng early - stage malgnant lesons n Syran hamster cheek pouch. Most of M. auratus had been used as laboratory anmals n medcal research, nowadays, the anmals are becomng popular as pet anmal, and t had been used as pet anmals n England snce 1880 (Grzmek, 1975).
Genetc nformaton can be obtaned by studyng body morphometry of M. auratus. Characterstcs n body sze and shape of M. auratus s determned through Prncpal Component Analyss (PCA); Factor Analyss (FA) s used to determne factors for classfyng body sze on the bass of relatons between body sze varbles whch are ndependent each other (Gaspersz, 1992). The last analyss can be vewed as an expanson analyss of PCA. The orgnal varables can be used as a factor f total varablty was approxmately 80 - 90% (Gaspersz, 1992).
Quanttatve characterstcs can be useful for conservaton and breedng de-velopment. Body sze of M. auratus s ncluded n medum sze (Henwood, 2007), but the hobbyst lke hamster wth small sze; as a result, body szes of M. auratus
s becomng the focus of ths study. Therefore, ths study s conducted to classfy
M. auratus nto large, medum and small body szes. Classfcaton through FA and PCA (Gaspersz, 1992) was carred out on the bass of lnear szes of body surfaces whch nclude body length (X1), chest wdth (X2), pelvc wdth (X3) and wrst cr-cumference of front arm or front leg (X4).
Materals and Methods
The experment was conducted n the Laboratory of Anmal Genetcs, Department of Anmal Producton and Technology, Faculty of Anmal Scence, Bogor Agrcultural Unversty, Bogor. Syran hamsters used n ths experment were 58 heads (24 males and 34 females) at the mature body age. Other materals used were verner calper and thread for measurng lnear varables of body surface. Hotellng T2-statstc was used to compare lnear measurements of body surface
between males and females wth the formula suggested by Gaspersz (1992). IfGaspersz (1992). If the results reject H0 hypothess, the two average values of lnear varables of body for were dfferent and the test were contnued wth FA (Factor Analyss) and PCA (Factor Analyss) and PCA (Prncpal Component Analyss).The FA used was calculated on the bass of formula suggested by Gaspersz (1992Gaspersz (1992) as follows : X
p = cp1 F1 + cp2 F2 + . . . + cpmFm + Єp
jth factor n composton from th respons; n FA was known as weghtng (loadng); n FA was known as weghtng (loadng)
. , n; wth descrpton: SF= matrx for factor score (descendant from covarance); Cdescrpton: SF= matrx for factor score (descendant from covarance); C: SF= matrx for factor score (descendant from covarance); C CC’=
matrx for weghtng factor (descendant from covaran); K KK-1= nvers from covaran
matrx K; X XXj= vector for observaton of jth ndvdu; X= vector average value from; X= vector average value fromX= vector average value from
varable X; n= sample sze.; n= sample sze. Classfcaton based on body measurements (small, medum and bg or large) was conducted usng formula recommended by Gaspersz (1992) whch were: large group f SF > SF + sSFs, medum group f SF – sSF < SF < SF + sSF, small group f SF < SF – sSF, wth descrpton: SF= factor score, SF=: SF= factor score, SF= SF= factor score, SF=SF= factor score, SF=, SF= SF= average of factor score, sSF= standard devaton of factor score., sSF= standard devaton of factor score.sSF= standard devaton of factor score..Prncple Component Analyss (PCA) by Gaspersz(1992), equaton model for body parts were: Yp= aYp= a1pX1 + a2pX2 + a3pX3 +a4pX4; wth descrpton:Yp= p descrpton:Yp= p:Yp= pth prncple component (p= 1, 2, 3,
4); X XX1= body length, X, XX2= chest grth, X, XX3= pelvc wdth, X, XX4= wrst-crcumference.-crcumference. Classfcaton on the bass of body lnear sze that was observed (small, medum and large) was conducted usng Garpersz (1992) formula large group: f yh1 > y1 + sy1;
lnear szes between male and female Syran hamster (P<0.01). These dfferences were also observed by Fox et al. (1984). The hghest body lnear sze varables nfluencng body szes of male and female hamsters was obtaned on the bass of communalty at Factor Analyss.
Tabel 1. Average and standard devaton for body lnear szes of male and female Syran hamster (Mesocricetus auratus) (cm)
Sex Body length Chest grth Pelvc wdth Wrst crcumference
♂ 9.45±0.70 (7.41%)1 1.87±0.15 (8.02%)1 1.12±0.09 (8.04%)1 1.54±0.14(9.1%)1
Table 2 showed the communalty (proporton of varablty of each varable orgn) n body lnear sze varables of Syran hamster. The results demonstrated that the body length (X1) was expressed as a factor F1 of body sze n males. Varable affectng the body sze of male Syran hamster n ths study was body length (X1). Ths varable had a value of 0.70 whch was the prmary factor affectng the body sze of male sgnfcantly. Accordng to Pontoh (2007), a weghtng factor value closng to +1 or -1 can be used as prmary factor. Body length of male Syran hamster showed a postve relatonshp between the closeness of the body length and the F1-factor. The hgher the body length then the body sze wll be greater n male. The results demonstrated that the body length (X1) was expressed as a factor F1 of body sze n females. Weghtng factor of body length (X1) on the F1 factor had the greatest value, e. -0.55. Accordng to Har, Jr. et al. (1998), the weghtng factor was greater than ± 0.50, but was not greater than ± 0.55; so the statstcal value of the weghtng factor has no effect. The results stated that body length was the man factor determnng body - sze n males, but not n females.
Body length n male, therefore, can be used as a reference n a selecton pro-gram based on body sze measurements that are not drectly related to body weght. Lnear sze of the body n Syran hamster observed was assocated wth the cond-ton of the body skelecond-ton.
Table 2. Factor weghtng (correlaton between orgnal varable wth factor), Egen value (λ), total variance (%), cumulative variance (%) and body size communality score of male & female Syran hamster (Mesocricetus auratus)
Varables measured (Male) Factor Communalty
score
F1 F2 F3 F4
Body length (X1) 0.70 -0.01 -0.00 -0.01 0.49
Chest grth (X2) -0.01 -0.13 0.08 -0.01 0.02
Pelvc wdth (X3) 0.04 -0.05 -0.03 0.06 0.01
Wrst crcumference (X4) -0.05 -0.09 -0.10 -0.03 0.02
Eigen value (λ) 0.50 0.03 0.01 0.00 0.54
Total varance (%) 91.1 5 3 0.9 100
Varables measured (Female) F1 F2 F3 F4
Body length (X1) -0.55 -0.04 0.01 -0.01 0.31
Chest grth (X2) 0.15 -0.16 0.04 -0.01 0.05
Pelvc wdth (X3) 0.01 -0.08 -0.09 0.00 0.01
Wrst crcumference (X4) -0.02 -0.01 0.00 0.08 0.01
Eigen value (λ) 0.33 0.03 0.01 0.01 0.38
Total varance (%) 87 8.6 2.5 1.9 100
Dscrmnatory varable for body szes of male and female Syran hamster were body length (X1) based on the hghest Egen value on body sze equaton (Table 3). Evertt and Dunn (1998) stated that the frst prncpal component represents the overall sze of the body must explan the total varablty between 50%-95%. The frst prncpal component s the body sze. Dscrmnatory varable for body shape of male and female Syran hamster were chest wdth (X2). Evertt and Dunn (1998) stated that the second prncpal component represents the overall body shape, must explan the total dversty of at least 1%.
Classfcaton the male Syran hamster can be performed based on the value of frst factor scores (SF-1) n Table 2; can be dvded nto large group wth SF-1 > 1.01 (fve heads), medum group wth SF-1 -1.01 to + 1.01 (13 heads) and small group wth SF-1 < -1.01 (sx heads). Classfcaton the female Syran hamster can be performed based on the value of frst factor scores (SF-1) that can be dvded nto large group wth SF-1 > 1.06 (fve heads), medum group wth SF-1 -0.94 to + 1.06 (13 heads) and small group wth SF-1 < -0.94 (sx heads).
Classfcaton based on the score of body sze based on Table 3 demonstrates that male wth a score value > 10.03 (fve heads) s for large group, a score value 8.63 to 10.03 (13 heads) s for medum group and a score value < 8.63 (sx heads) s for small group. The classfcaton for the females results n the score value > 9.02 (fve heads) for the large group, the score value : 7.88 to 9.02 (23 heads) for the me-dum group and the score value < 7.88 (sx heads) for the small group. Dstrbuton of Agout Non Golden (ANG), Agout Golden (AG), and Non Agout (NA) n each group of Syran hamster ndcated that the coat color was not related to body sze.
Concluson
Varable that affects the body sze of male M. auratus n ths study was body length; however, t dd not nfluence the body sze of female sgnfcantly. Body length was found as well as dscrmnatory varable for body sze of male and fe-male. Dscrmnatory varable for body shape of male and female M. auratus were
Table 3. Body sze and shape equatons wth the total dversty and Egen values n the Syran hamsters (Mesocricetus auratus) male and female
Sex Equaton Total
Dversty
Egen Value
Male Sze = X1 – 0.02X2 + 0.06X3 – 0.07X4 91.1% 0.50 Shape = 0.04X1 + 0.80X2 + 0.28X3 + 0.53X4 5.0% 0.03 Female Sze = 0.96X1 – 0.26X2 – 0.01X3 + 0.04X4 87.0% 0.33 Shape = 0.24X1 + 0.86X2 + 0.44X3 + 0.06X4 8.6% 0.03
chest wdth. The dstrbuton of colors that occur n each body sze class ndcated that M. auratus stll has a varety n coat colors. Classfcaton of body sze n M. auratus based on factor analyss and prncpal component analyss showed the same results.
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