Estimation of genetic and phenotypic parameters in a closed ...

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52 percent predicted yield, grade and age to r¡arket weíght, the coefficients ranged from low to hígh. The relationships between ham sur_ face and shoulder fat, mid-back fat and total back fat thickness measure* mentswere highly negative' whíle the relationshÍp betr¿een ham surface area and percent predicted yield was highly positive which suggested that selection for larger hau surface area would. increase percent predicred yield. The high negatíve correlations between percent predicted yield and back fat thíckness measurernents indicat.ed that selection for lower back fat thiekness would signifícantly increase the percent predicted yÍeld. selection for larger roin eye area, percent ham weight, ham surface area or grade index should lead to an increase in peïcent predicted yÍeld. The correlations betr¿een age to markeÈ weÍght and backfat thíckness measurements rùere highly negative except for loin fat which Índicated that sel-ection for fasL growth rate would Íncrease back fat thickness and decrease carcass grade index in consequence. The relationships between age Lo market weight and grade index, ham surface area and percent predícted yield were positive and high. These findings suggested that selectíon for lower back fat or hÍgher grade index or srnaller ham surface area or higher percent predicted yield would tend to increase age to market weight unless the traits \¡/ere combined in a selectÍon i-ndex.
53 SI]MMARY AND CONCLUSION Data from L,268 first parity gilts and from r,455 rnarket pigs of the Managra breed were analyzed to estimate phenotypic and. genetic parameLers for five reproductive trairs, ten carcass measurements and age at 90 kg live weight. Heritability estimates v¡ere calculated from Ëhe sire coûponent of variance. Three litter size traits including total number of pigs born, nurnber of pigs born alive and number of pigs weaned had lor¿ heritabilities i¿hich indicate that litt1e response would be expected from selection. Average birth weÍght and weaning weíght had moderate heritabilities which reveals that about 40"Á of the differences in these traits r'¡ere attributable to geneLic causes and r¡ould be expected to be transruitted to offspring from parents. Phenotypic correlations among three litter size traits were hÍgh1y positíve and generally agreed with the results from previous research. Average birth weight was moderately correlated phenotypically with average weaning weÍght. phenotypic correlations between litter sÍze tralts and average pig weight at birth and weaning were moderately negative except the correlation between nr:mber weaned and average pig birth weight. Genetic correlations between total number born and average birth weight and average r+eaning weight were 0.3010.46 and O.92t0.A9, respectively. Genetíc correlations between average pig weaning weÍght and nr-rmber of pÍgs weaned and average birth weight were 0.52!L.05 and O.L7XO.2L, respectively. Heri'tability estimates for carcass neasurements and age at 90 kg live weÍght T/¡ere anaLyzed by hierarchÍcal .analysis of varíance. Three carcass back fat thícknesses (maximum shoulder fat, minimum mid-back
Page 1 and 2:
ESTIMATION OF GENET]C AND PHENOTYPI
Page 3 and 4:
ACKNOI^rLEDGÐ{ENTS The author wish
Page 5 and 6:
iÍi carcass length,77.22!2.47 cm¡
Page 7 and 8:
TABLE OF CONTENTS Page B. Carcass m
Page 9 and 10:
va1 LIST OF TABLES Table Page L7 Me
Page 11 and 12: INTRODUCTION The heritabilíty of t
Page 13 and 14: granddaughter on granddam. The heri
Page 15 and 16: Table 1 (Contlnued) Tralcs a n Meth
Page 17 and 18: 7 r^/ith the number of pigs born al
Page 19 and 20: Table 2 (Contlnued) TraÍtg h2 Meth
Page 21 and 22: 11 as 0.31 and 0.40 by Edwardsand O
Page 23 and 24: 13 and backfat thickness r^7as nega
Page 25 and 26: Table 3. Managra breed development
Page 27 and 28: L7 Adjusted Y, = Y. - b (Xt-X") whe
Page 29 and 30: 19 9) 'PercenË Ham I{eight The pro
Page 31 and 32: 2I Table 6, Regression coefficients
Page 33 and 34: a') variance is given in Table 7. T
Page 35 and 36: 25 where: "ott(*y) 2 ã: "r(x) = to
Page 37 and 38: ¿/ l. Heritability estimates - The
Page 39 and 40: 29 Standard errors (S.E.) following
Page 41 and 42: 31 tots (*v) toto(*y) = totw(*y) =
Page 43 and 44: -f1 RESULTS AND DTSCUSSION A. Repro
Page 45 and 46: Table i-2. Means and standard devla
Page 47 and 48: a1 Table 13. Estímated heritabilit
Page 49 and 50: Table 14. PhenotypÍca and geneticb
Page 51 and 52: 4L Table 15 - Means and standard de
Page 53 and 54: 43 Table 16. Means and standard dev
Page 55 and 56: 45 Most of the heritabilities deriv
Page 57 and 58: 47 moderately heritable while carca
Page 59 and 60: ,o AJ et 41. (L969), Roy er al. (19
Page 61: 51 to phenotypic correlations in mo
Page 65 and 66: 55 also improve Ëhe others where s
Page 67 and 68: 57 Flock, D.K. 1970. Genetic parame
Page 69 and 70: APPENDIX s9
Page 71 and 72: Appendix rr. Anal-ysis of covarÍan
Page 73 and 74: Appendlx rrr' Ànalysfs of varlance
Page 75 and 76: Appendlx IV (Conrinued) Mean cross
Page 77 and 78: Appendlx IV (Conrlnued) Mean cross
Page 79 and 80: Appendlx IV (Contlnued) Mean cross
Page 81 and 82: ^Appendix IV (Continued) Mea4 cross
Page 83 and 84: Appendix IV (Conctnued) Mean crosà
Page 85 and 86: 75 Appendix V. Table of differentia
Page 87 and 88: 77 Appendix VI. (Continued) Body wt
Page 89: 79 Appendix VI. (Continued) Body wt
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