private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
A STUDY OF THE RELATIONSHIPS BETWEEN GROWTH,
CARCASS AND MEAT CHARACTERISTICS OF
ANGUS STEERS
A thesis presented in partial fulfilment o f the requirements f o r the degree o f Mas ter of
Agricultural S cience in Animal Science at Massey Univers ity
James Kundaeli Kileghua Msechu
1982
ABSTRACT
Growth , defined as change in weight , may be considered the mos t
important s ingle characteris tic of s laughter cat t l e . Fast-growing cattle may have bet ter food conversion and reach slaughter early . The end-
products in a beef product ion business , namely , carcass and meat , have properties which determine consumer acceptability. This study focussed attent ion on growt h , carcass and meat characteristics in cat t l e .
Literature was reviewed on factors that influence variability in these traits and relationships reported in the literature between some of the traits were summarised .
Records on 1 1 7 Angus steers born in 1 9 7 5 and 1 9 76 (years 1 and 2 ) were analysed by the leas t squares method o f f i t t ing constants . Data included birth weight , calf milk consumpt ion pre-weaning average daily gain (ADG) , weaning weight , post-weaning ADG , yearling weight , 2-year weight , f inish ( 30-month) weight , carcass weight , kidney and channel fat weight , eye muscle width, depth , and area , fat depth , fat trim p ercentage ,
intra-muscular fat percentage , sarcomere length , meat tenderness , musc le pH , and colour , lean per centage and b one percentage.
Fixed-effects constants f i t ted to growth data were : herd , age of dam and peri-natal treatment ( calving on pasture or s awdus t p ad ) .
Covariance analysis was adopted with 3 covariates : dam autumn l iveweight , calf birth weight , and milk consump t ion . Factors f i tted to post-
slaughter data were : maturity , slaughter lot and pre-slaughter fas t ing , with 3 covariates , carcas s weight , pre-weaning ADG , and post-weaning ADG .
iii
Resul ts were incons istent between years . Therefore , few factors were conclusively j udged to be important sources of variation in the
traits studied . Herd influenced milk consumpt ion (P<0 . 05 ) and pre- weaning ADG in year 1 , and weaning and yearling weight (P<0. 0 1 ) in year
2 . Age of dam did not affect growth traits (P>0 . 1 0 ) . Treatment was unimportant to pre-weaning growth in both years , but year 1 analyses sugges ted that it af fected post-weaning ADG (P<0 . 0 1 ) and finish weight
(P<0 . 0 5 ) . This result may be attributed to chance .
Regression on dam weight was non-s ignificant for all growth traits . Calf b ir th weight was found to be an important factor as far as various growth traits in year 2 were concerne d , namely , weaning weight (P<0 . 0 1 ) , and milk consump t ion , p re-weaning ADG and yearling weight (P<0 . 0 5 ) . Regression of weaning weight on birth weight approached signif icance
(P<0 . 1 0 ) , but b ir th weight was otherwise unimpo rtan t in year 1 . Milk consump t ion influenced weaning weight (P<0 . 0 5 ) in year 1 ; approached s ignificance for its effect on pre-weaning ADG and yearling weight in year 1 , and weaning and 2-year weight in year 2 (P< 0 . 1 0 ) .
Maturity did not affect pos t-slaughter charac teristics other than eye musc le depth (P<0 . 05 ) in year 2 . Slaughter lot was respons ible for var iat ion in eye mus cle width (P< 0 . 00 1 ) and dressing-out percentage
(P<0 . 0 1 ) in year 1 ; dress ing-out percentage and bone percentage (P<0 . 00 1 ) in y ear 2 .
Four-day pre-slaughter fast ing affected few carcass o r meat traits adj us ted for carcass weight by covariance analysis . The results were inconsis tent between years . In year 1 , fas ting affected dressing-out
percentage (P<0 . 00 1 ) only , while in year 2 such effect was not apparent (P>0 . 10) , but it was appreciable on other traits : eye muscle width and meat tenderness (P<0 . 05 ) and sarcomere length (P<0 . 00 1 ) .
Regression of various t raits on carcass weight was s ignificant : dress ing out percentage , kidney and channel fat , fat depth, intra
muscular fat percentage , fat trim p ercentage , eye muscle depth , eye muscle are a , sarcomere length , and bone percentage in year 2 ; it was signif icant for dressing-out percentage and kidney and channel fat in year 1 . Pre- and post-weaning ADG were less important covariates : the former was s ignificant to eye muscle depth , dressing-out percentage , intra-mus cular fat percentage and bone percentage in year 2 , but
non-significant in year 1 . The latter approached s ignificance in eye muscle are a , dressing-out p ercentage , fat trim percentage and b one percentage in year 2 (P<0. 10) .
Res idual sums of squares were used to estimate phenotypic
correlat ions between traits studied . Correlat ion coefficients between growth traits were positive and medium to high except those be tween early growth (pre-weaning ADG , and birth , and weaning weigh t s ) and post-weaning ADG , which were negligibl e . Pre-weaning ADG and weaning weight had a perfect correlat ion coef ficient ( r = 1 . 0) in both years . Est imates between growth and carcass traits varied widely ; notab le were those for post-weaning ADG , 2-year weight , and f inish weight with carcass weight , which were high in both years (r = 0 . 86 , 0 . 80 ; r = 0 . 80 , 0 . 85 ; and r = 0 . 9 2 , 0 . 92 , respectively ) .
V
Carcass traits were mos tly posi t ively correlated , with low to medium coe f ficients be tween them. Lean percentage had a strong negat ive correlation with fat trim percentage (r = - 0 . 7 1 ) , but bore lit tle relationship with o ther traits . Correlation coefficients between carcass and meat traits were mos tly pos i t ive , but low and
incons istent between years . Carcass weight was related to mos t fatness at tributes of the carcass and meat . Most meat traits were positively correlated with each other with low and medium correlation coefficients .
A C K N 0 W L E D G E M E N T S
A number o f people and organizations helped cons iderably in different ways in this s tudy . It is not poss ible to list the names of all who contributed - sometimes indirectly - towards this s tudy , but the author wishes to express his thanks to all those who discussed matters related to this work and are no t ment ioned individually here . Notable among these are computer s c ientis ts at the Massey Univers i ty Computer Centre and several s taff and graduate s tudents in the Sheep Husbandry Department at Mass ey University .
Mr R . A . Barton and Professor A . L . Rae were supervisors o f the author's s tudy p rogramme and offered valuable ideas and encouragement . Mr Barton helped with part o f the data collection and offered con- s truc tive criticism and guidance in writing this thesis . Professor Rae discussed some aspects o f the analyses with the author who wishes to thank his supervisors for their advice and help .
Professor R . D . Anderson o ffered advice on, and ins truc tion in Biome t rics . His willingness to discuss problems on s tatis tical
procedures made an invaluab le contribution towards the author's readiness to tackle the analyses . He also lent some calculat ing
facilit ies for the preliminary analyses and I wish to record appreciation for this .
Dr R . W . Purchas , Mr S . N . McCutcheon and Mr D . R . Pat terson helped in collecting pos t-s laugh ter data . Dr Purchas of fered valuable
vii
suggestions on many aspects of the post-slaughter characteristics . Mr Patterson f iled mos t o f the growth records o f the experimental animals and furnished the author with all necess ary information . S incere thanks are expressed to these persons .
Staff at the Massey University sheep and beef cattle farms managed the experimental animals . Staff at the C . W . S . freezing works , Longburn , Feilding Abattoir and Evans Export Ltd rendered tremendous help in slaughtering and in collecting post-slaughter data . The author wishes to thank them for their co-operation .
The Comb ined Beef Breeders ' Research Committee ( Inc . ) made financial grants for various beef cattle studies , of which this thes is is part ; the author wishes to express h is appreciation for this . The Helen E . Akers S cholarship was awarded to the author and he expresses his appreciation to the Trustees o f the S cholarship for this ass istance .
The author wishes to record his gratitude to the New Zealand and Tanzania Governments for making it pos s ible for h im to undertake graduate studies at Massey Univers ity .
Mrs A . F . Barton and Mrs R . A . Vining typed this thes is . The author wishes to thank them for their skill and care .
Finally , I wish to express special thanks to my family for their encouragement and unequalled forbearance at the temporary loss of
companionship which the undertaking of this work and earlier s tudies at Massey Universi ty necess itated .
Any inadequacies , or inaccuracies in this thes is are the sole respons ibility of the author and should not be viewed as shared respons ibility with any of the organizations or persons who of fered help or views as s tated or implied in the foregoing paragraphs .
· LIST OF FIGURES AND TABLES
Figure
1 . 1 Curve of l iveweight growth in cattle
1 . 2 An illus tration o f differential growth in the three major tissues of beef cattle
Table
2 . 1 Some pub l ished es t imates of genetic and phenotypic correlation o f b irth weigh t with pre-weaning growth and weaning weigh t
2 . 2 Some pub l ished es t imates of gene t ic and phenotypic correlat ion of b irth weight with pos t-weaning growth and weights
2 . 3 Some pub l ished e s t imates of genetic and pheno typic correlation of weaning weight with pre- and pos t-weaning growth
2 . 4 Some published es t imates o f gene t ic and phenotypic correlation between weaning weight and later weights
2 . 5 Some published es timates o f genetic and pheno typic correlation between some pos t-weaning growth traits
2 . 6 Estimates of genetic and phenotypic correlation between growth and carcass traits (adap ted from Pres ton and Willis , 1 9 7 4 )
2 . 7 Some es timates of gene tic and pheno typic correlation b e tween growth and carcass t raits
2 . 8 Some es t imates o f genetic and pheno typic correlation between growth and meat traits
2 . 9 Some pub lished es t imates of genetic and pheno typic correlations between carcass traits
i x
Page 4
6
6 1
65
6 8
7 1
74
7 7
8 1
84
87
Table
2 . 10 Some publ ished estimates o f genetic and phenotypic correlation b etween carcass and meat traits 2 . 1 1 Some publ ished estimates o f genetic and phenotypic
3 . 1
correlation between meat characteristics
Sub-class numbers of s teers for which growth data
(pooled over 2 years o f study) were analyzed
3 . 2 Sub-class numbers o f steers for which post-slaughter
4 . 1 4 . 2 4 . 3 4 . 4 4 . 5 4 . 6
data were analyzed
Analyses of pre-weaning growth traits Analyses of post-weaning growth traits Analyses o f carcass measurements
Analyses of some carcass composition characteristics Analyses of meat characteristics
Analyses of carcass measurements for influence of pre-s laughter fasting
4 . 7 Analyses of carcass composition characteristics
4 . 8
that may have been influenced by pre-s laughter fasting
Analyses of meat characteristics for influence o f pre-slaughter fasting
4 . 9 Summary o f correlation coe f f icients between s ome
4 . 10
growth traits
Summary of correlation coe f f icients between some growth and carcass characteristics
4 . 1 1 Summary of correlation coe f f ic ients b etween some
4 . 1 2
growth and meat characteristics
Summary of correlation coef f icients b etween some carcass traits
94
99
106
1 1 3 1 25 1 2 9 1 3 1 1 3 3 1 35
1 3 7
1 39
140
1 4 2
1 4 5
148
1 5 1
Table
4 . 1 3 Summary o f correlation coefficients b etween some carcass and meat characteris t ics
4 . 14 Summary o f correlation coefficients between some meat charac teris tics
Appendix Table Al . 1
Al . 2
A1 . 3
A2 . 1 A2 . 2
A2 . 3
A2 . 4
A2 . 5
A2 . 6 A2 . 7
B3 . 1
B3 . 2
Sub-class means o f weaning ( 200-day) weight f rom data pooled over both years o f study
Sub-class means o f yearling weight from data pooled over both years of s tudy
Sub-class means of finish (30-month) weight from data pooled over both years of s tudy
Sub-class means of carcass weight (kg )
Sub-class means of fat dep th measurements (mm) over the eye mus cle
Sub-class means of eye mus cle area (sq . in . ) recorded in year 2
Sub-class means o f intra-mus cular ( chemical) fat percentage
Sub-class means o f fat trim percentage from year 2 data
Sub-class means o f lean percentage from year 2 data Sub-class means of meat tenderness (Warner-Bratzler
shear force in kg ) values
Preliminary analys is of weaning weigh,t . Testing main factors having adj us ted for covariates Preliminary analys is of weaning weigh t .
the s ignificance of covariates
Testing
xi
1 5 3
1 5 6
1 6 3
164
165 166
167
168
1 6 9
1 70 1 7 1
1 7 2
180
1 80
Appendix Table
B3 . 3 Summary o f preliminary analyses of l iveweight at various stages to test for s ignificance of age of dam x treatment interaction and individual covariates
C S imple correlation coefficients b etween the
D
principal traits under s tudy : calculated from the data without considering the various factors explained in Chapter 3 .
Coefficients o f determination (r x 100) between 2 the principal traits under study : calculated from correlation coefficients p resented in Chapter 4 .
182
1 84
185
TABLE OF CONTENTS
Page
ABSTRACT ii
ACKNOWLEDGEMENTS vi
LIST OF FIGURES AND TABLES xi
CHAPTER 1 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 CHAPTER 2
2 . 1 2 . 1 . 1 2 . 1 . 1 . 1 2 . 1 . 1 . 2 2 . 1 . 2 2 . 1 . 2 . 1 2 . 1 . 2 . 2 2 . 1 . 3 2 . 1 . 3 . 1 2 . 1 . 3 . 2 2 . 1 . 4 2 . 1 . 4 . 1 2 . 1 . 4 . 2
INTRODUCTION 1
Beef and the Meat Consumer 1
Growth and Development in Cattle 2
Post-slaughter Characteristics 8
Relationships Between Beef Cattle Traits 10 The Obj ectives o f this Study 1 4
REVIEW OF L ITERATURE 15
Factors Influencing Beef Cattle Traits 15 Pre-natal Growth and Birth Weight 1 6
Genetic Factors 1 7
Non-genetic Factors 1 7
Post-natal Growth to Weaning 2 2
Genetic Factors 2 2
Non-genetic Factors 25
Post-weaning Growth 29
Genetic Factors 30
Non-genetic Factors 34
Post-s laughter Characteristics 38
Genetic Factors 39
Non-genetic Factors 4 5
2 . 2 2 . 2 . 1 2 . 2 . 2 2 . 2 . 2 . 1 2 . 2 . 2 . 2
2 . 2 . 2 . 3 2 . 2 . 3
2 . 2 . 3 . 1 2 . 2 . 3 . 2 2 . 2 . 4
2 . 2 . 4 . 1 2 . 2 . 4 . 2 2 . 2 . 4 . 3 CHAPTER 3
3 . 1 3 . 2
3 . 2 . 1 3 . 2 . 1 . 1 3 . 2 . 1 . 2 3 . 2 . 2 3 . 2 . 2 . 1 3 . 2 . 2 . 2 3 . 2 . 2 . 2 . 1
Relationships Between Beef Cattle Traits Introduction
Relationships Between Growth Traits
Pre-weaning Growth Traits
Pre-weaning and Post-weaning Growth Traits
Post-weaning Growth Traits
Relationships Between Growth and Post
slaughter Characteristics Growth and Carcass Traits Growth and Meat Traits
Relationships Between Carcass and Meat Traits
Carcass Traits
Carcass and Meat Traits Meat Characteristics MATERIALS AND METHODS Source of Data
Experimental Animals - Management and Data Collection
Cows
Management Recording Steers
Management Recording Growth Data
5 5
5 5 5 7 5 7
64 70
7 3 76 83
8 3 86 9 2 9 3 100 100
1 0 1 10 1 10 1
1 0 2 1 0 2 1 0 2 104 104
CHAPTER 3 ( continued) 3 . 2 . 2 . 2 . 2 3 . 2 . 2 . 2 . 3 3 . 2 . 2 . 2 . 4 3 . 3
3 . 3 . 1 3 . 3 . 2
3 . 3 . 3 3 . 3 . 4 3 . 3 . 4 . 1 3 . 3 . 4 . 2
3 . 3 . 4 . 3
3 . 3 . 4 . 4
CHAPTER 4 4 . 1 4 . 1 . 1 4 . 1 . 2 4 . 1 . 2 . 1
4 . 1 . 2 . 2 4 . 2
4 . 2 . 1 4 . 2 . 2 4 . 2 . 3
Pre-slaughter Procedure
Slaughter and Post-s laughter Procedures Measurement of Meat Characteristics Statistical Procedures
Introduction
Data Clas s i fication
Linear Model Construction Analyses
Least Squares Equations and Solutions Sums of Squares and ANOVA Table
Construction
Alternative Orders of Fitting Factors in a Model
Methods for Generating Estimates o f Correlation Coe f f icients
RESULTS AND D ISCUSS ION Analyses of Variance Growth Traits
Carcass and Meat Traits
The Influence of Maturity and Slaughter Lot
The Influence of Pre-s laughter Fasting Relationships Between Characteristics
Studied
Growth Characteristics
Growth and Post-slaughter Traits Carcass and Meat Traits
106 107 1 10 1 13 1 1 3 1 14
1 1 5 1 18 1 18
120
1 20
1 2 2
1 24 1 24 1 24 130
1 30 1 3 6
14 1 1 4 1 144 1 4 9
5 . 1 . 1 5 . 1 . 2 5 . 2 5 . 2 . 1 5 . 2 . 2
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
Growth Traits
Carcass and Meat Characteristics Relationsh�ps Between Traits Growth and Post-slaughter Traits Carcass and Meat Traits
Data Summaries
Analysis of Variance - An Illustrative Example of Procedures for Obtaining Sums of Squares
S imple Correlation Coe f f i cients Bet\veen the Principal Traits under Study ; Calculated f rom the Data Without Considering the Various Factors Explained in Chapter 3
Coe f ficients o f Determination ( r2 x lOO) Between the Principal Traits under Study ; Calculated from Correlation
1 5 7 1 5 8 1 5 8 1 5 8 160 1 6 2
1 7 3
1 84
Coe f f i cients Presented in Chapter 4 1 8 5
B IBLIOGRAPHY 1 8 6
