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A STUDY ON THE BREEDING PERFORMANCE OF ROMNEY AND BORDER LEICESTER CROSS ROMNEY
EWE LAMBS AFTER CIDR TREATMENT
A thes i s presen t ed in par t i al ful f i lment o f the requi remen t s for the degree of Mas ter of Agr i cul tural
Science in Ani mal Sc i ence at Massey Un ivers i ty Palmers ton Nor th
New Zealand
BAE SEOK CHUN 1987
ABSTRACT
The reprodu c t ive per fo rmance of 1 1 7 Border-Le i ces t er X Romney ( BLX ) and 91 Romney ewe hogge t s in 1984 and 108 BLX and 101 Romney i n 1 985, was s tud i ed af ter t rea tmen t wi th cont rolled i n t e rnal drug
releasers ( CIDRs ) con t ain ing proge s t e rone or wi th polyure t hane s ponges con t a i ni ng medroxyproge s t e rone ace t a t e (MAP ) . To induce and
synchron i se oes t rus at the beginning of the breed ing season ,
proges t agens were admini s t ered for 1 1 - 1 2 days . The animals were j o ined w i t h t easer rams or wi th en t i re rams and data collec t ed on t he
occurrence and synchroni za t i on of oes t rus , concep t i on and lamb i ng performance .
In 1986, 36 lambs o f each o f the Romney or BLX geno types were used i n a s tudy t o d e termine the t i me of ovulat i on af ter t rea tmen t wi th CIDRs e i ther wi t h or wi t hout 200 i . u . PMSG inj ec t ed a t CIDR
w i t hd rawal . Laparos copies were car r i ed ou t one o r more t i mes a t 54 , 60 , 66,72 hours and one week af ter CIDR wi thd rawal t o d e termine t he occurrence o f ovula t ion . The release of proges terone f rom t he CIDR was mon i t ored in blood samples from en t i re animals and from ovariec t omi sed animals during t reatmen t and af ter wi thd rawal of t he CIDRs .
Following proges t agen wi thdrawal , 69% and 42% o f sponge- t rea t ed hogge t s and 45% and 40% of CIDR- t rea t ed an imals were in oes t rus over 5 days i n the two years , respec t i vely . In 1986 , fol lowing proge s t agen wi t hdrawal , 61% and 83% of animals came i n t o oes t rus wi t h i n 3 days i n CIDR- and CIDR + PMSG- t rea t ed ewe lambs .
The mean t i me o f ovula t i on was 67 h and 65 h in CIDR and CIDR + PMSG t rea t ed animals , respec t i vely . The inci dence of mul t i ple ovula t i on was s i mi lar in CIDR- (15%) and Sponge - t rea ted (20% ) ewe lambs . Al though the inj e c t i on of a small amoun t o f PMSG caused a h i gher inc idence o f mul t i ple ovul a t i on than in CIDR- t rea t ed ewe lambs , the d i f ference was no t s i gn i f i can t . The concep t i on rate was higher i n ani mals t re a t ed in 1984 than in t h e next year ( 6 9% v 49% ) . Trea t men t
11
or breed d i f fe rences i n concep t i on we re no t s ign i f i can t but i n 1985 t he BLX an i mals had a reduced concep t i on ra te o f only 38%; the Breed X Year i n terac t i on was s i gni f i can t ( P < 0 . 05 ) . There were only a few mul t i ple b i r t hs recorded and the ges t a t i on leng th was no t a f fec t ed by t rea t men t . S i gn i f i can t b i r t h we ight effec t s due t o year and breed were appare n t , bu t only a d i f ference due to year occurred i n the wean i ng weigh t s . The fleece we igh t s recorded a t one year age were n o t
i n fluenced b y t he t reatmen t s , but year e f fec t s were i mpo r t an t .
Proges t e rone levels in blood plasma o f ovar i e c t om i s ed ewe lambs reached a max i mum by 24 h af ter CIDR inser t i on , then dec l i ned gradually and an abru p t fall resul ted soon a f t e r CIDR wi thd rawal . In the e n t i re lambs w i th CIDRs the levels o f proges terone remai ned h i gh un t i l
w i t hdrawal and then fell t o basal levels cons i s t e n t wi th ovulat i on . A f t e r t h i s the levels rose and were s i mi lar t o that i n an i mals wi t h a corpus l u t eum of a na tural oes t rous cycle .
I t was concluded that CIDR t reatmen t can i nduce ear l i er breed i ng v' among ewe lambs and that the induced ovula t i on resul t ed i n a normal corpus l u t eum . The pregnancy ra t e a f t er CIDR t reatment was i n fluenced by year e f f e c t s and t h i s was probably assoc i a t ed wi th d i f ferences i n l ivewe ight among t h e ewe lambs .
iii
ACKNOWLEDGEMENTS
I gra t e fully acknowledge the gu i dance and ass i s tance o f my supervisor Dr . M . F . McDonald dur i ng the expe r i men t al work and the prepara t i on o f this manus c r i p t .
I am inde b t ed to Mr . J . M . Rendel for adv i ce and a i d i n the s ta t i s t i cal analy s i s o f t he data and i n compu t e r opera t i on .
Spe c i al t hanks are due t o Mes srs M . G . Di vehall , M . A . Wycherly, M . L . Car t er and M . P . Di ckson for t he i r ski lled t echn i cal ass i s t ance .
Gra t eful acknowledgemen t i s made to Mr . P . M . Wh i tehead , Sheep Farm Superv i s or and to W . S . Mor r i s , and L. W i l l i ams for care of t he an i mals . Acknowledgemen t i s also made t o Dr . K . Lapwood and Mr . J . Elgan for t he i r advice and ass i s tance i n the proges terone assay wo rk .
Grat eful i s ex t ended t o Dr . R.A.S. Welch of D.S.I.R. for helpful d i s cuss i on on aspec t s of the t reatmen t of sheep wi t h CIDRs . Spec i al thanks are due t o my col legues M i s s . M . Da t t ena, M i s s . L . Anne McCleland, M r . R . S . Rangel , Mr. A. W i l l i s and P . Morgan wi th whom I had many reward i ng d i scus s i ons .
Also I am grat eful to t he pos tgradua tes of the An i mal S c i ence Depar tmen t for the i r f r i end s h i p and hosp i t al i t y dur i ng the pe r i od of my s t udy .
F i nally very s pecial t hanks are due to my paren ts for t h e i r suppo r t and encouragemen t throughou t t h i s s tudy .
IV
LI ST OF TABLES
TABLE
4 . 1 E f f e c t o f breed , t reatment and year on the incidence o f ewe lambs oes t rus before t rea tment period
4 . 2 E f f e c t o f breed , t reatmen t and year on the inci dence o f ewe lambs oes t rus dur ing and a f t er t reatmen t
4 . 3 E f f e c t o f t reatmen t and year on the i n terval be tween Sponge or CIDR removal and the ons e t of oes t rus
4 . 4 Analy s i s o f var i ance o f fac to rs influencing the i n te rval o f ons e t o f oes t rus
4 . 5 E f f e c t o f breed and t reatment on the inc idence of mul t i ple ovula t i on
4 . 6 E f fec t o f breed , year and t reatmen t on conce p t i on ra t e i n marked ewe lambs
4 . 7 E f f e c t o f breed , year and t reatmen t on conce p t i on rate i n the lambs j o ined wi t h rams
4 . 8 E f f e c t o f breed , t reatmen t and year on ges t a t ion leng t h 4 . 9 E f f e c t o f breed , t reatmen t and year on t he day o f b i r t h
in ewe lambs
4 . 10 Inci dence of mul t i ple b i r t h in ewe lambs 4 . 1 1
4 . 1 2
E f f e c t o f breed , E f f e c t o f breed , lambs weaned per
t reatment and year on b i r t h we igh t t reatment and year on the percen t age ewe lamb j o ined
o f
page
3 2 3 3 35 39 40 43
44 47
48 52 53
55 E f f e c t o f breed , t reatment and year on hogge t fleece weigh t
4 . 1 3 56
4 . 14 Plasma proges t erone level dur ing and a f t e r CIDR t rea t men t
in en t i re and ovar i ec t omi sed (OXV ) ewe lambs 58 4 . 1 5 Proges t erone levels in en t i re ewe lambs t rea ted wi t h CIDRs 6 1 4 . 1 6 Proges t erone levels in en t i re ewe lambs a f t er t re a t ment wi t h
CIDRs
4 . 1 7 Propor t i on of ewe lambs wh ich ovula ted by var i ous t i mes a f t e r CIDR wi thd rawal
4 . 18 E f f e c t of breed of hogge t , t reatmen t and laparoscopy group
63 66
on t he inc idence o f ovula t i on by 1 week af ter CIDR wi t hd rawal 67 4 . 1 9 Di s t r i bu t i on o f hogge t s in wh i ch twin ovula t i ons occurred
a f t e r CIDR wi t hd rawal 68
4 . 20 Di s t r i bu t ion o f animals ovula t i ng by various hours af t e r CID�
wi thdrawal 70
4 . 2 1 E f f e c t o f breed and t reatmen t on the mean t i me of ovula t i on
V
a f t e r wi thdrawal of CIDR 7 1 4 . 22 Compa r i son o f t i me of ovula t i on (h af ter CIDR wi thd rawal )
be tween groups o f hogge t s 7 2
4 . 23 E f fe c t o f breed, t reatmen t and group on the incidence o f
oes t rus wi thin 7 days o f CIDR w i t hd rawal 7 4 4 . 24 E f fe c t o f breed, t reatment and group o n t h e occurrence o f
oes t rus a t t h e expe c t ed second oes t rus af ter CIDR wi t hd rawal 75 4 . 25 E f fe c t o f breed and t reatmen t on the i n t erval be tween CIDR
removal and the onse t o f the f i rs t oes t rus 7 7 4 . 26 Breed and t reatmen t effec t s on the synchron i za t i on o f oes t rus
one cycle a f t e r CIDR wi thdrawal
4 . 27 E f f e c t o f breed , t reatment and group on cycle leng t h
80 84
vi
LIST OF FIGURES
FIGURE
4 . 1 Di s t r i bu t ion o f the ons e t of oes t rus af ter proges t agen wi t hdrawal
4 . 2a E f fe c t o f breed on t he d i s t r i bu t ion of ons e t of oes t rus a f ter proge s t agen wi thdrawal -1984
4 . 2b E f fe c t o f breed on the d i s t r i bu t ion of ons e t of oes t rus af t e r proges tagen wi thdrawal -1985
4 . 3a Di s t r i bu t i on o f day of bi r t h -Ma t i ng group 4 . 3b D i s t ri but ion of day of b i r t h -Sponge group 4 . 3c D i s t ri bu t ion of day of bi r t h -CIDR group
4 . 4 Mean plasma proges t erone levels dur ing and af ter CIDR t reatmen t i n ewe lambs ( Exp . 1 )
4 . 5 Mean plasma p roges t erone levels during CIDR t reatmen t i n ewe lambs ( Exp . 2 )
4 . 6 Mean plasma proges terone levels af ter CIDR t reatmen t i n CIDR only , CIDR + PMSG and con t rol groups ( Exp . 2 ) 4 . 7a Di s t r i bu t ion o f onse t o f t he f i r s t oes t rus
( re l a t ive t o t reatmen t )
4 . 7b Di s t r i bu t i on o f onse t o f t he f i rs t oes t rus ( rela t i ve t o t rea tmen t and breed )
4 . 8a Di s t r i bu t i on o f onse t o f the second oes t rus ( re l a t ive to t reatmen t )
4 . 8 b D i s t r i bu t i on o f ons e t o f the second oes t rus ( re l a t ive t o t reatmen t and breed )
page
36 37
38 49 50 5 1 5 9 6 2 64 78 79 81 82
Vjj
ABSTRACT
ACKNOWLEDGEMENTS LI ST OF TABLES LI ST OF FIGURES TABLE OF CONTENTS
TABLE OF CONTENTS
page
CHAPTER ONE
INTRODUCTION . .. . . . . . . . .. . . . . . . . . . . . .. . . . . . . . 1
CHAPTER TWO 2 . 1 . 2 . 1 . 1 . 2 . 1 . 2 . A ) B ) C ) 2 . 2 . 2 . 2 . 1 . 2 . 2 . 2 . 2 . 2 . 3 . 2 . 2 . 4 . 2 . 2 . 5 . 2 . 2 . 6 . 2 . 2 . 7 . 2 . 3 . 2 . 3 . 1 . 2 . 3 . 2 . 2 . 3 . 3 . 2 . 4 . 2 . 4 . 1 . REVIEW OF LITERATURE . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . .. 3
ASPECTS OF PUBERTY . .. . . . . . . . . .. . . . . . . . . . .. . . 3
De f i n i t i on . . . . . . . . . . . .. . . . . . .. . . . .. . . . . . . . . . . . . .. . . 3
Endocri nology of puber ty . . . . . . . . . . . . . . . 3
Dur i ng foe t al developmen t . . . . . . .. . . . . . . . . . . . . . .. . . . 3
Dur i ng early pos t na t al per i od . . . . .. . . . . . . . . . . .. . . . 4
Dur i ng puber tal per i od . . . . . . . . .. . . . . . . .. . . . . 6
FACTORS AFFECTING FIRST OESTRUS . . . . . . . . .. . . . . . . . . . . . . . 7
Breed . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . .. . . . .. . . 7
Age and Body weigh t . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . 8
Nu t r i t i on . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . .. . 8
Pho toperiod . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . .. 9
Ex t e roce p t ive fac tors . . . . . . .. . . . . . . . . . . . . . . . .. . . . 1 0 Tempera tu re . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . 1 1 Exogenous ho rmones . . . . .. . . .. . . . . . . .. . . . . .. . . . . 1 1 ARTI FICIAL CONTROL O F OESTRUS AND OVULATION . . . . . . . . . . 1 2 Proges t e rone and i t s analogues . . . 1 2 M e l a ton in . . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . 1 3 S teroid i mmun i z a t i on . . . .. . . . . . . . . .. . . . .. . . . . . . . . . . 14
TIME OF OVULATION . .. . . . .. . . . . . . . . .. . . . . . . . . . .. . . . . . 1 4 Fac tors a f fec t ing t i me of ovulat ion . . . . . . . . . .. .. . . 15
viii
2 . 4 . 1 . 1 . 2 . 4 . 1 . 2 . 2 . 4 . 1 . 3 . 2 . 4 . 1 . 4 . 2 . 4 . 1 . 5 .
2 . 5 . 2 . 5 . 1 2 . 5 . 2 .
2 . 6 . 2 . 6 . 1 . 2 . 6 . 2 . 2 . 6 . 3 . 2 . 6 . 4 .
Season .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . 1 5 Age . . . . . . .. . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . .1 5
Hormonal t reatmen t e f fec t . . . .. . . . . . . . . . . . . .. . . . . . . 16
Ram e f fec t . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . .. . 1 6 S t ress .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . .. . . . .. . . . 16
PROGESTERONE IN PERIPHERAL BLOOD . . . . . . . . . . . . .. . . . . 17
Prepube r t al period . . . . . . . . . .. . . . . . . . . . . . .. . . . . . .. .. . . 17
Oes t rous cycle . . . . .. . . . . . . . .. . . . .. . . . . . . . . .. . . . . .. 17
REPRODUCTIVE PERFORMANCE . . . .. . . . . . . . . . . . . . . .. . . . . . . 18
Oes t rus and ovula t ion . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . 1 8 Concep t i on . . . . . . . . .. . . . . . .. . . . . .. . . . . . . . . . . .. . . . . . . . . 1 9 Embryo mor t al i t y . . . . . . . . . . . . .. . . . . , . . . 20
Lamb mor t ali ty . .. . . . . . . . . . . . .. . . .. . . . . . . . . . .. . . . 2 1 PURPOSE AND SCOPE OF INVESTIGATION . . . . . .. . . . . . . . . . . . . . .. . . . .. . . . 2 2 CHAPTER THREE 3 . 1 . 3 . 2 . 3 . 2 . 1 . 3 . 2 . 2 . 3 . 2 . 3 . 3 . 2 . 4 . 3 . 2 . 5 . 3 . 2 . 6 . 3 . 2 . 7 . 3 . 3 . 3 . 4 . MATERIALS AND METHODS . . . . . . . .. . . . . . . . . . . .. . . . . . . . 2 3 ANIMALS . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . 2 3 EXPERIMENT 1 : INDUCTION O F BREEDING . . .. . . .. . . . . . .. . . . 2 3 Mat ing records . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . 2 3 Synchron i za t i on o f oes t rus . . . . .. . . . . . . . . .. . . . .. . . 2 6 Blood sampling and proges terone analy s i s . .. . . .. . . 2 6 Ova r i an ac t i vi ty . .. . . . . . . .. . . . .. . . . . . . . . . . . . .. . . .. . 2 7 Fleece we igh t . . . .. . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . 2 7 Lambing managemen t . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . 28
Wean ing . . . .. . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . 28
EXPERIMENT 2 : TIME OF OVULATION . . . . . . .. . . . . . . . . . . . . . . 2 9 ANALYSIS O F DATA . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . 30 CHAPTER FOUR
RESULTS . . . . . .. . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . 3 1
4 . 1 . 4 . 1 . 1 .
A ) B ) 4 . 1 . 2 . 4 . 1 . 3 . 4 . 1 . 4 . A ) B ) C ) D ) E ) 4 . 1 . 5 . 4 . 1 . 6 . 4 . 2 .
4 . 2 . 1 . 4 . 2 . 2 . A ) B )
4 . 3 . 4 . 3 . 1 . 4 . 3 . 2 . 4 . 3 . 3 . A ) B ) 4 . 3 . 4 . A ) B ) 4 . 3 . 5 . 4 . 4 .
X
E'WE LAMB PERFORMANCE . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . 3 1 Incidence o f oes t rus . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . .3 1 Be fore t rea t men t . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . . . . . 3 1 A f t e r t rea t men t . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . • . . . . 3 1 Synch ron i z a t ion of oes t rus . . . . . . . . . .. . . . . . . . . . . . . . . . . 3 4 Inci dence o f mul t i ple ovula t i on . . . . .. . . . . . . . . . . . . . 3 4 Pregnancy . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . 4 1 Concep t ion ra t e . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . 4 1
Ges t a t ion leng t h . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . 45
Day o f b i r t h . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . 45
Incidence of mul t i ple b i r t h . . . . . . . . . .. . . . . . . . . . . 46
B i r t h weigh t .. . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . 46
Lambs weaned . . . . . . . . . . . .. . . . . . . . . . .. . . . .. . . . .. . . . . . . . 54
Fleece produ c t ion . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . 54
PLASMA PROGESTERONE LEVELS IN EWE LAMBS TREATED 'WITH CIDR . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . .57
Expe r i men t 1 . . . 57
Exper i men t 2 . . . . . . . . .. . . . . . . . . .. . .. . . . . . . . . .. . . . 60
Proges t e rone levels during CIDR t reatment . . . . . . . . . . . .60
Proges t e rone levels a f t e r CIDR t reatmen t . . . . . . .. . . . . . 60
OVULATORY ACTIVITY AFTER CIDR WITHDRA'WAL . . . . . .. . . .. . . 65
Incidence o f ovula t i on .. . . . . . . . . .. . . . . . . . . . .. . . . . . . . . 65
T i me o f ovula t i on . .. . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . .69
Inci dence o f oes t rus . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . 7 3 Expec t ed " f i rs t " oes t rus . . . . .. . . . . . . . . . . .. . . . . . . . 7 3 Expec ted " second " oes t rus . . . . . . . . . .. . . . . . . . .. . . . . . . . . 7 3 Synchron i za t ion of oes t rus . . . . . .. . . . . . . . . .. . . . . . . . . . . 76 Expec t ed " f i rs t " oes t rus . . . . . . . . . . . .. . . . . . . .. . . . . . . 7 6 Expec t ed " second " oes t rus . . . . .. . . . . . . . . . . . .. . . . . . . . . . 7 6 Cycle leng t h . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . .8 3 APPLICATION AND RETENTION OF CIDRs AND SPONGES . . . . . . .8 5
CHAPTER FIVE
5 . 1 . 5 . 1 . 1 . 5 . 1 . 2 . 5 . 1 . 3 . 5 . 1 . 4 . 5 . 1 . 5 . 5 . 1 . 6 . 5 . 2 .
5 . 3 .
5 . 4 .
DI SCUSSION AND CONCLUSION . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . 86
REPRODUCTIVE PERFORMANCE AFTER CIDR TREATMENT . . . . . .. . . . . .86
Incidence o f oes t rus . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . •.86
Synchron i z a t i on of oes t rus . . .. . . . . . . . . . . . . . . . . • . • 87
Ova r i an ac t i vi ty . . . . . . . . . .. . . . . . . . .. . . . . . .. . . . • . . . • . • 89
Pregnancy . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . •. . . •.91
Lambing performance . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . •9 2 Fleece we igh t . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . .. . . •. . . •. . . . .93
UPTAKE OF PROGESTERONE FROM CIDR . . . . . . . . . . . .. . .. . .. . .. . . .95
PROGESTERONE PRODUCTION AFTER INDUCED OVULATION . . . . . . . . .. 96
CONCLUSION . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . .. . . . .97
REFERENCES . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . .98
xi
