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A
thesis pr esented in par tial fulfilment of the r equirement s for the degree of Master of Agr i cultural Sc ience in AnimalSc ienc e a t Massey Univer sity
ABDUL MAJID MOHAMED
1 976 .
ABSTRACT
The data used in the present study were col lec t ed from wether lambs of a flock of New Zealand Romney she ep star t ed at Massey Agricultural C ollege , Palmerston Nor th, in 1 944.
The lambs , 474 in number , wer e t he progeny of 1 2 mixed-age rams born over a per iod of thr e e years from 1 944 to 1 947 . Altogether , 25 carcass traits wer e analys e d .
i i .
A linear mathematical mode l , which included sire , year and type o f bir th and rear ing as the main effects , a sir e-year interac tion t er m and age at slaughter as a covariat e , was used to descr ibe t he data . T he estimates of the various terms in t he mode l were derived by least-squar e s pr ocedures. Preliminary analyses inc luded determining the s ignificance of t he sir e-year interac t ion in each of the 25 trai t s . In traits where the sire-year interaction were found no t significant , the main effec ts an d regression t erm were estimated.
Varianc e c omponent s wer e estimated using Hend erson ' s Me thod III . Heritabil ity was estimate d by paternal hal f-sib c o rrelati on.
The proce dures used in the estimation of covarianc e comp one nts w ere, in many ways, simi lar to th ose used in the analysis of variance c omponent s . In the former, the sums of crossproducts for the appropriate effects w ere computed from the differenc e
between two reductions in sums of crossproducts .
S ire-year interaction was found to be significant in four trait s , namely width of gigot (G) and the ratio of the weight of the forequarter to the hindquarter (FQ/HQ) at the 1% level of probability and, carcass grade and cannon bone weight at the 5% l eve l of probability.
Estimates of heritability of carcass trai ts are as fo llows : Internal measurements :
A,
1 . 1 1 ± 0 . 27;B,
0.20 ± 0 . 1 2;C, 0 . 31 ± 0. 1 4�
D ,
0 . 27 ± 0 . 1 3; X , 0 . 09 ± 0 . 08; Y, 0 . 28 ±0 . 1 4; J' 0 . 35 ± 0 . 1 5 .
Measurements indicative of bone length and weight : F , 0 . 73
± 0, 22; T , 0 . 62 ± 0 . 2 0; R, 0 . 55 ± 0 . 1 9; P, 0 . 70 ± 0, 22;
Cannon bone length, 0 . 80 ± 0 . 23; cannon bone weight , 1 . 01 +
0 . 26 .
Measurements indicat ive o f width o r depth o f body: G, 0 . 41
± 0. 1 7; WR, 0.1 4 ± 0 . 1 0; WF, 0 . 09 ± 0 .08; WTh, 0 . 37 ± 0 . 1 6;
Th, 0 . 67 ± 0 , 2 1 .
Measurements indicative of length of body : K , 0 . 34 ± 0 . 15;
1, 0. 55 ± 0 . 1 9; H, 0.20 ± 0. 1 2 .
"Other" carcass t rai t s : carcass weight, 0 . 03 ± 0 . 04;
carcass grade, -0 . 04; carcass total , 0 . 34 ± 0. 1 5; FQ/HQ, 0.00.
Est imates o f genetic c orrelati o ns showed large sampling errors.
The correlati ons between t he rati o o f t he weight o f the fo requarter
t o the hindquarter (FQ/HQ) and the o t her carcass traits were not included because the sampling errors were very large, In t !1e
maj ority o f cases , the geneti c c o rrelati ons were o f the same s ign
\'
'as the phenotypic co rrelat i ons.
ACKNOWLEDGMENTS
The author wishes to extend his grat itude and respect to his supervisor, P rofessor A.L . Rae , for the invaluable assistance an d guidan ce rende red by him in a l l aspects o f the study .
iv.
The assistance of Mr. R.A. Ba rton, who so willingly checked through the manuscript and made valuable suggestions , are
sin c e re ly appreciated.
M r . R.D. Ande rson and Mr. A . B . Pleasan t s helped in comput ing matt e rs and for this they are since rely thanke d.
Thank s are due als o to the staff of the Computer Un it , Mas s ey Un iversity, for making freely avai lable the facilities.
L ast , but not l east , the author extends his appreciation to Mrs. M . Brogden , Mrs . A .F . Barton and Mrs . J . A . Jepson for the i r ski l led typing of t he manuscript.
Chapter
2
3
TABLE O F CONTENTS
ABSTRACT ii
ACKNOWLEDGMENTS iv
LIST OF TABLES ix
FIGURE 1 55
INTRODUCTION
REVIEW OF LITERATURE 5
I. CARCASS WEIGHT AND CARCASS MEASUREMENTS AS
INDICES OF CARCASS COMPOSITION 5
A. Carcass weight as an index of carcass
composition. 5
B. Carcass measurements as indices of carcass
bone content . 7
C . Carcass measurements as indices of the amount
of muscle . 1 1
D. Carcass measurements as indices of fat content . 18
II. HERITABILITY OF CARCASS TRAITS 24
III. GENETIC AND PHENOTYPIC CORRELATIONS AMONG
CARCASS TRAITS
)7
DATA 48
48 5 1 5 1 5 1 52 52 5 6 5 6
r. SOURCE OF DATA
II . DES CRIPTION 6F CARCASS DATA A. Cannon bone measurements
B. Carcass grading
c. Carcass weight
D. Carcass measurements E. Carcass total
:F.
FQ/HQ
Chapter 4
5
STATISTI CAL METHODS
I . LEAST-SQUARES ANALYSIS
II . ESTIMATION OF SIRE-YEAR INTERACTION III. ESTIMAT ION OF VARIANCE COMPONENTS A. Mode l wi thout interaction
B. Model with interaction IV. ESTIMATION OF HERITABILITY
vi .
5 7 5 7 6 2 66 70 73 77 V . ESTIMATION OF COVARIANCE COMPONENTS 80 A. No interaction term in both traits 81 B . Interaction term signifi cant in both trai ts 84 C. Interaction term significant in only one trait 87 VI . ESTIMATION OF GENETIC AND PHENOTYPIC
CORRELATIONS
RESULTS AND DISCUSSION
I . SAMPLE MEANS AND STANDARD DEVIATIONS II. THE I NTERACTION OF SIRES AND YEARS III. THE MAIN EFFECTS AND REGRESSION TERM
87
91 91 91 99
IV. ESTIMATES OF VARIANCE COMPONENTS 1 02 V. ESTIMATES OF HERITABILITY OF CARCASS TRAITS
I N THE NEW ZEALAND ROMNEY 1 02
A. Internal measurements 1 05
B. Measurements indicative of bone length and
weight 1 08
c. Measurements indicative of width or depth of
body 1 1 0
D. Measurements indicative of length of body 1 12 E. The "other" carcass t raits 1 13
Chapter 5
6
VI. ESTIMATES OF GENETIC AND PHENOTYPIC CORRELATIONS AMONG CARCASS TRAITS IN Tllli
NEW ZEALAND ROMNEY 1 1 6
A. Among internal measurements 1 1 6
B. Between internal measurements and measurements
indicative of bone length and weight 1 1 8
c.
Between internal measurements and measurementsindicative of width or depth of body 1 2 1 D. Between int ernal measurements and measurements
indicative of length of body 124-
E. Between int ernal measureme nts and the "other"
carcass traits
F. Among measurements indicative of bone length
12 6
and weight 1 29
G. Between measurements indicative of bone length and weight and, those indicative of
width or depth of body 131
H. Between measurements indicative of bone length and weight and, those indicative of
body length 1 33
I . Between measurements indicative of bone length and weight and , the "other" carcass t raits
J. Among measurement s indicative of width or depth of body
K. Between measurements indicative of width or depth of body and those indicative of length
135 1 35
of body 1 38
L. Between measurements indicative of width or
depth of body and the "other" carcass traits 1 40 M. Among measurements indicative of length o f
body 142
N. Between measurements indicative of length of
body and the "other" carcass traits 1 44 0. Among the "other" carcass traits 1 44
CONCLUSION 148
·I
Iviii.
Page
APPENDIX I 1 57
APPENDIX I I 1 58
APPENDIX III 159
APPENDIX IV 1 60
APPENDIX V 1 6 1
APPENDIX VI 1 62
APPENDIX VII 1 63
APPENDIX VIII 165
BIBLIOGRAPHY 1 67
Table 2 . 1
LIS T OF TABLES
Published estimates of heritabil ity of carcass traits in sheep
2 . 2 Published estimates of pheno typic and genetic correlati ons between eye muscle area and
backfat thickness and, other carcass t raits in sheep
2 . 3 Publ ished estimates of pheno typic and genetic correlations between carcass length and , backfat thickness and eye muscle measurements in pigs
3 . 1 3 . 2
Number of wether lambs according to sire, year and birth rank
The " Cambridge" block t est judging scale
4 . 1 Analysis of variance table for the estimation
o f variance c omponents in the case of no interaction
4 . 2
4 . 3 4 . 4 4 . 5
Analysis of variance table for the estimat i on of variance c omponents in the presence of sire-year interaction
Analysis of covariance for the case where there
is no interaction term in both traits
Analysis of c ovariance table for the case where the interaction terms are signifi cant in both traits
Expected composit ion of c ovariance components 5,1 Means and standard deviat ions for the various
carcass traits
34
43
47
49 5 6
7 2
75 83
86 88
92 5.2 Test of s ignifi cance of the s ire-year interaction 93 5. 3 Sire-year interaction effecLs for width o f gigots
(G)
. 96Table
5 . 4 Sire-year int eraction effects for carcass grade 97 5 . 5 Sire-year interaction effects for cannon bone
weight 97
5.6 Sire-year interac tion effects for the ratio of the weights of the forequarter to the hindquarter
( FQ/HQ) 98
5 . 7 F-Values for test ing the signifi cance of the main effects and the regression term for traits
whe re sire-year interaction is non-significant 1 00 5 . 8 Estimates of variance components for various
carcass traits 5 . 9
5 . 1 0 5 • 1 1 5 . 1 2
Additive genetic variance and estimates of he ritabi lity of carcass traits
Est imates of heritability of " length" and depth of eye musc le in pigs
Estimates of phenotypic and genetic correlati ons among internal carcass measurements
Est imat es of phenotypic and genetic corre lations between internal measurements and , measurement s indicative of bone length and weight
Est imates of phenotypic and genetic corre lations between internal measurements and measurements indicative of width or depth of body
Estimates o:t phenotypic and genetic corre lations between internal measurements and meas�rements indicative of body length
5 . 1 5 Estimates of phenotypic and gene ti c corre lations between internal measurements and the "o ther"
carcass traits
5 . 1 6 Estimates of pheno typic and genetic correlations among measurements indicative of bone length and weight
1 03 1 04 1 06 1 1 7 1 20 1 22 1 25
1 30
x.
5 . 1 7
5 . 1 8
5. 1 9
5 . 20
5 . 2 1
5 . 22
5 . 23 5 .24
5.25
Estimates of phenotypic and genetic correlations between measurements indicative of bone length and weight and , those indicative of width or depth of body
Est imates of phenotypic and genetic correlati ons between measurements indicative of bone length and weight and , those indicative of length of body
Est imates of pheno typic and genetic co rrelations between measurements indi cative of bone length and weight and the "other" carcass traits
Est imates of phenotypic and genetic correlations among measurements indi cative o f width or depth of body
Est imates of phenotypic and genetic correlat ions be tween measurements indicative of width or depth of body and those indicative of length of body
Es timates of pheno typic and genetic corre lations be tween measurements indicative of width or depth of body and the "other" carcass traits Estimates of pheno typic and genetic correlat ions among measurements indicative of length of body Estimates of pheno typic and genetic correlations between measurements indicative of body length
and the "othe:r" carcass traits
Estimates of pheno typic and gene tic corre lations among the "other" carcass traits
1 32
1 34
1 36
1 37
1�0 )./
1 4 1 1 43
1 45
1 46
