A study of some aspects of selection for the fertility of New Zealand Romney ewes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science

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:::;ci.cmcc ..

J. n. C L A R. K �

LIBRARY

MASSEY UNIVERSITY OF MANAWATU PALMERSTON NORTH, N.Z.

'lbe candi.oote wishes ^to ellpl"'&s his gratit:ude to IOOI!lbcrs of the

Ua.asey TJrd'IOrs:lv College staf':f tor tho bolp whioh be bas reoe1W<l et-an tham du:ring this inventi{ru. tion.

Special tl�emla:s tlt'e �"tended to hi.a superv.tsore, Prof'esnor A.L. Ro.o and Mr. T.s. Ch'llllgJ to Mr. ll.A. BartonJ to !Jiu IJ.G. Csz:pbell o.nd hor

Ubrw:y otafta and to his V1ifu Wld Miss r.._ Christenaen far 'tm>ine this

ljbea1s.

P'l-llL"'lleicl MDiat.:.'.."1CO f.'ror.l u Zl0-r1 iklcl-:L.!.nd .ool Doal-d Scholr.'.rship, in cJ.oo t.,"'U�.llly ttclmot:led.:·;o0.,.

A. Intl"''duotion

n. .!.JOf'lni t:lon and r:oo.suror:xmt of l:�li cy

c. Et"i,ootn of !lon-eoootio Vootors on &.10 Fort:Ui ty

1. N_"';; of .im

2. Your E :feet on the Pc.,:-tlli1({ o£ Ema

.3. lnfiUOl'lCO of o-tlmr Ilon-aenotic Eft'oots D. !-:videnoe of Gcmtic V�.rlntl.on in 1-'ort:i.l.icy

1. Dctuoon Th.� Genetic V .. .ri<.� tion

2. .i thin J)ro(sod Gonotic Vnr.L.ltion

�0 or n:i.l"t!l �.:!'foot

Bnti:x::.. to::: of : �cpw tabili 'fV' of �(.opro<1uo ti ve

el-:C'OI ^._ •.nee

Bstin.-.tcn of' :m .l t.�ili w o1' G.er..ro<l.<Ctivc

Po:::i��t'"!<.,�I.CC

��i-e l::f':;\�-ct of ��-ID)S on tile Fc.:tlliitf o:f tlloir

U.mr;h�s

&.lloot::on :.::O�)crJ..r.lO,Its �·or J.\:Jr'dli t; ::1n :.:rle<-"P

r.:.. ConclusiO'.tlS

J,. Objootn of tJ10 Iuvooti,; ti.on B. � Hoorurooent of Fartilifzy'

(i) 1

1 2 4 8 5

10 9

10 11 12 14

1G

1U 1n ^"-'

21

25

rv. ��OURCL OE DATA 27

Introduction

n. Estir:ntion of Genetic Parmootors

1. RopoatabUi ^f\1

2. Her1tcld.llfar 6'

Method at .Ana13'eie 65

Reeulto Ga

(i) I..cr:ID procl.1et1on of ocros c1.:•.oai.f-lod c.eoord.i.nc

to the n'J!.""lbcr of lo;::bs born at the

tooth lcz.:ilin:; or tooir � 68

(ii) ';be effect of birth r.:L�-: 0::1 the n:lt'Jbor of>

1.:1.::1>s born 70

(iii) � ::?rotluction of cooo ol.::asi.t'iod ^on tho

t>csio c£ the tninnin(; i'CCO!'Cs of t!:10ir d::�o 72

Disc'.losion

C ^• E�ootcd Gcins �m 5eloetion Indi �cl or �s Solect:lon

Rosponso to Sclcctio..l'l

�:-raphiccl lloproacntntt0n of Selection U.oQonsc

�9 �1.xl �f>

-..:rr:.lysis end roaul ts

{u) ^{D:t.oo .Dcl.on}

s�.IDd:i. vi<lir-c the '"'l10not.7i;.lc Cb.ooon

r.::!:c Uoo o£' Aiili:l to :i:.o[.l So1cction

?ro O!�./ J.Coti4_;

redly Belocticf!

L:.for�.o.:';io::J on P...nccst'"'rc :JOL-:bl:lt.'d � .... cloc-:���n �.cl�os

I ••) '). •• ··:·:...J.• :1,

75

82

8.3 8.3 87 JG 90 94

;)5 9G 93

1 CY.J' �9

t.. ��::::;etion 101

1. Jori��T-.:.:�"n :::f .l'1!lc�: :-.-.r�tio:1o ·ic.=

2. Seloction I�1d:ices �-;:;::- Led l?roductio� 1::;5

.3. .'�cl_tivo :t'.i."'iolcnc.J of !..__'"ib ?rod .-�tion 1nuicoa 109 4.. ^3.oL_tive ·:.c.:i.;;�·xtir;G !ncto:-e for �.:n L .. dox IL&Jd on .lie.D1s

.�yJ. !wf-r'.i:; . .s' Pcr-Z�r-.:nnoo 112

5. Diacuooion 113

c. Appl.iee:.tion of ';.•;o 1.a:lb Production Indices 114

1 � Index P.roccd:.lrc 114.

Indoz b6DOCl ^on l'eCOrds of tho daD

In4ez. on rooorde of tbo 0114 tbe balf--siaters

114 118 119 119

121 �21

122 12J 127 ,,,

''l:.'woe ye:..1r ly by L..tl!lbill[; rich r.-.astors do r.u!�,

Tho li!Clbs or such twinnors, for brco&...·,rs �;o ttw�. ^'1

- mm roua.tt (18.37)' ^as quoted by

Wentnortb and Sweet ( 1917).