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Flushin Condicion Corporal

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  • 8/3/2019 Flushin Condicion Corporal

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    HumphreyC. V. Hulet, R. L. Blackwell, S. K. Ercanbrack, D. A. Price and R. D.

    Production in Range EwesEffects of Feed and Length of Flushing Period on Lamb

    1962, 21:505-510.J ANIM SCI

    http://jas.fass.org/content/21/3/505

    services, is located on the World Wide Web at:The online version of this article, along with updated information and

    www.asas.org

    by guest on January 13, 2012jas.fass.orgDownloaded from

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    E F F E C T S O F F E E D A N D L E N G T H O F F L U S H I N G P E R I O DO N L A M B P R O D U C T I O N I N R A N G E E W E S

    C. V. HU LET, R . L . BLACKW ELL, S. K . ERCANBRACK,D . A . P R I C E A ND R . D . H U M P H R E YU . S . D e p a r t m e n t o / A g r i c u l t u re

    i T i s a n a c c e p t e d p r a c t i c e o f m a n y s h e e pp r o d u c e r s t o f l u s h e w e s p r i o r t o a n d d u r -i n g b r e e d i n g f o r t h e p u r p o s e o f i n c r e a s in g l a m bp r o d u c t i o n . H e a p e ( 1 8 9 9 ) , M a r s h a l l ( 1 9 0 8 ) ,M a r s h a l l a n d P o t t s ( 1 9 2 4 ) , N i c h o ls ( 1 9 2 6 ) ,D a r r o c h e t a l . (1950) , W i l l i a m s ( 1 9 5 4 ) , W a l -l a ce ( 1 9 5 4 ) H o v e r s l a n d e t al. ( 1 9 5 6 ) , C a m p -b e l l et al . (1959) a n d m a n y o t h er s h a v e f o u nda p o s i t i v e e f f e c t o f f l u s h i n g o n t h e n u m b e r o fl a m b s b o r n . H o w e v e r , f l u s h i n g h a s n o t a l w a y sb e e n f o u n d e f f e ct iv e . C l a r k ( 1 9 3 5 ) p o s t u l a t e dt h a t w h e n e w e s a r e i n h i g h c o n d i t i o n , f l u s h -i n g w i l l n o t i n c r e a s e t h e i r o v u l a t i o n r a t e .D a r l o w ( 1 9 4 2 ) s u g g e s te d t h a t s o m e e w e sh a v e a l o w g e n e t i c p o t e n t i a l i t y f o r t w i n n i n ga n d w i l l s h o w n o r e s p o n s e t o f l u s h i n g . E w e sh a v e b e e n f l u s h e d f o r v a r y i n g l e n g t h s o f t i m e ,b u t m o r e s p e c if i c i n f o r m a t i o n i s n e e d e d o nt h e e f f e c t o f l e n g t h o f t h e f l u sh i n g p e r i o d a n dt h e t i m e f l u s h i n g i s s t a r t e d r e l a t i v e t o t h eb e g i n n i n g o f t h e b r e e d i n g p e r i o d o n l a m b p r o -d u c t i o n . T h e g e n e r a l r e c o m m e n d a t i o n i s t of l us h f o r 2 t o 3 w e e k s p r i o r t o a n d d u r i n gt h e b r e e d i n g p e r i o d .O n e o b j e c t i v e o f t h i s s t u d y w a s t o d e -t e r m i n e w h e t h e r o a t s o r a l f a l f a p e l l e t s g i v e na s a s u p p l e m e n t t o d r y , a s a g e b r u s h - g r a s s - t y p ep a s t u r e o r n a t i v e g r a s s h a y f e d p r i o r t o a n dd u r i n g t h e b r e e d i n g s e a s o n w o u l d b e e f f e c -t i v e i n i n c r e a s i n g l a m b p r o d u c t i o n u n d e rc o n d i t i o n s p r e v a i l i n g a t t h e U . S . S h e e p E x -p e r i m e n t S t a t i o n . T h e s e c o n d o b j e c t i v e w a st o d e t e r m i n e t h e e f f e c t o f l e n g t h o f t h e f l u s h -i n g p e r i o d a n d t h e t i m e o f c o m m e n c i n g t h ef l u s h i n g t r e a t m e n t s r e l a t i v e t o t h e t i m e o fs t a r t i n g t o b r e e d o n l a m b p r o d u c t i o n .

    M a t e r i a l s a n d M e t h o d sA p p r o x i m a t e l y 1 2 0 0 C o l u m b i a a n d T a r -g h e e e w e s ( 4 0 0 h e a d f o r e a c h o f 3 y e a r s - -1 9 57 , 1 9 58 a n d 1 9 5 9 ) w e r e r a n d o m i z e d w i t h i n

    1 F r o m t h e U . S . S h e e p E x p e r i m e n t S t a t i o n a n d W e s t e r nS h e e p B r e e d i n g L a b o r a t o r y , S h e e p a n d F u r A n i m a l R e s e a r c hB r a n c h , A n i m a l H u s b a n d r y R e s e a r c h D iv i s io n , A R S , D u b o i s ,I d a h o i n c o o p e r a t i o n w i t h t h e U n i v e r s i t y o f I d a h o . P u b l i s h e dw i t h t h e a p p r o v a l o f t h e d i r e c t o r o f t h e I d a h o A g r i c u l t u r a lE x p e r i m e n t S t a t io n , M o s c o w , a s R e s e a r c h P a p e r N o . 5 4 4 .

    a g e a n d b r e e d i n g p e n i n t o e i g h t e x p e r i m e n t a lg r o u p s ( t h e o a t t r i a l ) a s s h o w n i n t a b l e 1 . A ni d e n t ic a l , s i m u l t a n e o u s e x p e r i m e n t u s in g 1 l b .o f a l f a l f a p e l l e t s ( t h e a l f a l f a t r i a l ) i n li e u o f0 . 7 l b . o f o a t s w a s c o n d u c t e d o n a c o m p a r a b l eg r o u p o f e w e s o f t h e s a m e b r e e d s a n d a g e s .T h e f e e d i n g r a t e s w e r e c a l c u l a t e d t o p r o v i d ee q u i va l e nt a m o u n t s o f T D N . M a n y o f t h ee w e s r e f u s e d t h e p e l l e t s f o r a f e w d a y s t h ef i r s t y e a r .T h e e w e s w e r e w e i g h e d t h e l a s t o f O c t o b e ra n d a g a i n a t t h e e n d o f b r e e d i n g . T r e a t m e n tw a s c o m m e n c e d a b o u t N o v e m b e r 1. E a c h d r y -l o t b re e d i n g p e n ( e w e s a s s i gn e d t o o n e r a m )w a s d i v i d e d t o a l l o w th e e w e s a s s i g n e d t ot r e a t m e n t s 5 , 6, 7 a n d 8 t o r e c e iv e t h e i r o a to r a l f a l f a p e l l e t s u p p l e m e n t . T h e r a m a s s ig n e dt o e a c h p e n w a s s h i f t e d d a i l y a t 1 1 a . m . a n d1 1 p . m . f r o m o n e h a l f o f t h e p e n t o t h e o t h e rh a l f f o r t h e 3 4 - d a y b r e e d i n g p e r io d . A r a n d o mh a l f o f th e r a m s w e r e w i t h e a c h s u p p l e m e n t e do r n o n - s u p p l e m e n t e d g r o u p a t a n y g i v e n t i m e .T h e e w e s w e r e h a n d l e d i n a t y p i c a l r a n g eo p e r a t i o n p r e c e d i n g a n d f o l l o w i n g t h e e x p e r i -m e n t a l p e r i o d .A l t h o u g h t h e s u b c l a s s n u m b e r s w e r e s l i g h t l yd i s p r o p o r t i o n a t e , t h e d a t a w e r e a n a l y z e d b yc o n v e n t i o n a l a n a l y s i s o f v a r i a n c e b e c a u s e i tw a s f e l t t h a t a n y r e s u l t i n g b i a s i n t e s t s o fs i g n i f i c a n c e a n d e s t i m a t e s o f m e a n s d u e t ot h i s d i s p r o p o r t i o n w o u l d b e n e g l i g i b l e . E r r o rt e r m s f o r t e s t i n g s i g n i f i c a n c e o f m a i n e f f e c t sa n d i n t e r a c t i o n s w e r e s e l e c t e d a s d e s c r i b e d b yS n e d e c or ( 1 9 5 6 ) a n d H e n d e r s o n ( 1 9 6 0 ) f o ra m i x e d m o d e l . T r e a t m e n t s a n d b r e e d s w e r ec o n s id e r e d a s f ix e d a n d y e a r s a s r a n d o m v a r i a -b le s . D u n c a n ' s ( 1 9 5 7 ) m u l t i p l e r a n g e t e s t w a su s e d t o t e s t d i f f e r e n c e s a m o n g t h e e i g h t t r e a t -m e n t m e a n s . H o v e r s l a n d et al . ( 1 9 5 6 ) a n dW i l li a m s ( 1 9 5 4 ) h a v e in d i c a te d t h a t 2 - y e a r -o l d e w e s m i g h t r e s p o n d d i f f e r e n t ly t o f l u s h in gt r e a t m e n t s t h a n t h e m a t u r e e w e s . F o r t h i sr e a s o n , a n d a l s o b e c a u s e a n a n a l y s i s i n c l u d i n gb o t h a g e g r o u p s w o u l d h a v e r e s u l t e d i n h i g h l yd i s p r o p o r t i o n a t e s u b c l a s s n u m b e r s , t h e d a t af r o m t h e t w o a g e g r o u p s w e r e a n a l y z e d s e p a -

    50S

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    5 06 H U L E T , E T AL .TABLE 1. TREATMENT GROUPS

    Trea tmen t Seventeen days ~ First half Second halfnum ber prior to breeding breeding (17 days) breeding (17 days)1 (control) Pasture b Hay Hay2 (control) Hay c Hay Hay3 Pastur e & Supplement a Hay Hay4 Hay & Supplement Hay Hay5 Pastur e & Supplemen t Hay & Supplement Hay6 Hay & Supplement Hay & Supplement Hay7 Pasture & Supplement Hay & Supplement Hay & Supplement8 Hay & Suppleme nt Hay & Supplement Hay & Supplement

    a Only 16 days in 1957.b Dry, sagebrush-grass-typepasture.e Native grass hay fed in bunks in drylot and during breeding.a Whole oats at the rate of 0.7 lb. head per day (oat trial) or alfalfa pellets at the rate of 1.0 lb. per head per day (alfalfatrial).r a t e ly . D a t a p r e s e n t e d a re b a s e d o n n u m b e ro f e w e s p r e s e n t a t l a m b i ng t i m e .

    R e s u l t s a n d D i s c u s s io nT h e t r e a t m e n t m e a n s f o r n u m b e r o f l i v el a m b s b o r n , p o u n d s o f l iv e l a m b b o r n , p o u n d so f l a m b w e a ne d , l a m b i ng da t e , g r e a s e f l e e c ew e i g h t , p r e t r e a t m e n t w e i g h t a n d c h a n g e i nb o d y w e i g h t d u r i n g t h e t r e a t m e n t p e r io d f o re w e s p r e s e n t a t l a m b i ng a r e s how n i n t a b l e 2 .F r o m t h e a n a l y s e s o f v a r i a n c e i t w a s f o u n dt ha t t r e a t m e n t d i f f e r e nc e s i n t he oa t t r i a l f o rm a t u r e ew e s w e r e s i g n if i ca n t ( P ~ . 1 0 ) f o r

    n u m b e r o f l iv e l a m b s b o r n a n d p o u n d s o f l iv el a m b b o r n . T o t a l p o u n d s o f l a m b w e a n e d ,g r e a s e f le e c e w e i gh t a nd l a m b i ng da t e w e r ea f fe c te d b y t r ea t m e n t s ( P ~ . 0 6 ) . C h a n g e i nb o d y w e i g h t d u r i n g t r e a t m e n t w a s s i g n i f ic a n tl ya ff ec te d b y t r e a tm e n t s ( P ~ . 0 1 ) i n b o th t ri a lsw i t h m a t u r e e w e s . T h e r e w a s n o s i g n i f i c a n tb r e e d e f f e c ts bu t d i f fe r e nc e s be t w e e n ye a r s ha da s i gn i f i c an t e f f e ct on pou nds o f l a m b w e a ne d ,g r e a s e f l ee c e w e i gh t a nd c ha nge i n w e i gh td u r i n g t r e a t m e n t p e r i o d . A l t h o u g h t h e t r e a t -m e n t m e a n s f o r n u m b e r o f l i v e l a m b s b o r n ,p o u n d s o f l i v e l a m b b o r n a n d p o u n d s o f l a m bw e a ne d f o r m a t u r e e w e s i n t he a l f a l f a t r i a lsugge s t a f lush ing e f fec t on th e pe l le t s , thedi f fe rences were n ot s ign i f i cant .T h e o n l y t r e a t m e n t e ff e ct s w h i c h w e r e s i g-n i f i c a n t , i n e i t he r t r i a l , w i t h 2 - ye a r - o l d e w e si n v o l v e d ch a n g e s i n w e i g h t d u r i n g t r e a t m e n t .T h e a p p a r e n t g r e a t e r l a m b - p r o d u c t i o n r e -s p o n s e t o t r e a t m e n t b y t h e m a t u r e c o m p a r e dt o 2 - ye a r - o l d ew e s in t he o a t t r i a l i s in ge n e r a la g r e e m e n t w i t h f i nd i ngs o f t he s t ud i e s p r e v i -ous l y c i t e d .

    I n d i v i d u a l t r e a t m e n t c o m p a r is o n s a re s h o w ni n t a b l e 3 f o r num be r o f l i ve l a m bs bo r n ,p o u n d s o f l i v e l a m b b o r n a n d p o u n d s o f l a m bw e a ne d . T r e a t m e n t s 3 , 4 , 5 a nd 6 w e r e a l l

    c o n s i s t e n tl y b e t t e r t h a n t r e a t m e n t s 1 a n d 2f o r a l l t h r e e m e a s u r e s o f l a m b p r o duc t i o n ; bu tt he d i f f e r enc e s w e r e no t a l l s i gn i f ic a n t a t ( P ~. 05 ) . N o s i gn i f ic a n t d i ff e r enc e s i n l a m b p r oduc -t i o n w e re f o u n d a m o n g t r e a t m e n t s 3 , 4 , 5 a n d6 ; t hus t he s e t r e a t m e n t s w e r e e s s e n t i a ll y e qua l .F r o m a p r a c t i c a l s t a ndpo i n t , t he 17 - da y p r e -b r e e d i ng f l u s h i ng t r e a t m e n t s ( t r e a t m e n t s 3 &4 ) w o u l d b e m u c h m o r e e c o n o m i c al t h a n t h o s ee x t e n d i n g b e y o n d t h i s p e r i o d ( t r e a t m e n t s 5 &6) . T r e a t m e n t 8 d i f f e r ed s i gn i f i ca n t l y f r omt r e a t m e n t s 3 a n d 5 in n u m b e r o f l iv e l a m b sbo r n , t h i s i n c on j unc t i on w i t h o t he r e v i de nc eg i ve n be l ow s ugge s ts a de t r i m e n t a l e f f e ct o fp r o l o n g i n g f l u s h i n g b e y o n d t h e t i m e t h a tm o s t e w e s a r e b r e d o n s u b s e q u e n t l a m b p r o -duc t i on .F i gu r e 1 il l u s t r a te s t he e f f ec t s o f l e ng t h o ff lu s h in g p e r io d o n l a m b p r o d u c t i o n . T h e r e w a sg r e a t s i m i l a r i t y be t w e e n e f f e ct s o f c om p a r a b l et r e a t m e n t s ( 1 a nd 2 , 3 a nd 4 , 5 a nd 6 , 7 a nd8 ) on t he t w o m a j o r g r oups o f e w e s r e c e i v i ngp r e b r e e d i n g t r e a t m e n t s o n s a g e b r u s h - g r a s spa s t u r e ( t r e a t m e n t s 1 , 3 , 5 , 7 ) ve r s us g r a s sha y ( t r e a t m e n t s 2 , 4 , 6 , 8 ) . T he s e r e s u l t ss t r ong l y s ugge s t t ha t a s ho r t f l u s h i ng t r e a t -m e n t a d m i n i s te r e d d u r i n g t h e e a r l y p a r t o ft he c yc l e c a n g i ve op t i m u m r e s u l ts , w he r e a sc o n t i n u e d f e e d i n g f o r t o o l o n g b e y o n d c o n -c e p t i o n m a y b e d e t r i m e n t a l t o l a m b p r o d u c -t i on . I n ge ne r a l , t he s e r e s u l t s s uppo r t t hef i nd i ngs o f R obe r t s on e t a l . ( 1 9 5 1 ) , S e l f e t a l .( 1 9 5 5 ) , E 1 S h e i k h e t a l . ( 1 9 5 5 ) a n d F o o t ee t a l . ( 1 9 5 9 ) w h i c h in d i c a t e d e t r im e n t a l e f -f e c t s on e m br yo s u r v i va l o f e x t e nd i ng a h i ghl e ve l o f n u t r it i o n t h r o u g h 2 5 a n d 4 0 d a y s o fge s t a t i on f o r g i l t s a nd e w e s , r e s pe c t i ve l y .W a l l a c e ( da t a pub l i s he d by G e r r i ng , 1954 )f ound , by obs e r v i ng t he t w i nn i ng r a t e o f e w e sw h i c h he l d t o s e r v i c e a f t e r t he y ha d be e nf l u she d on pa s t u r e f o r va r y i ng l e ng t h s o f t i m e ,t h a t a m a x i m u m r e s p o n s e w a s o b t a i n e d a f t e r

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    FLUSHING ON LAMB PRODUCTIONTABLE 2 . MEANS FOR LAMB PRODUCTION, GREASE FLEEC E WEIG HT AND OTHER

    T RAI T S I N T ARGHE E AND COL UM BI A E WES BY FL USHI NG T RE AT M E N T

    507

    Treat- No. l i v e L i v e G r e a s e P r e t r e a t m e n t C h a n g em e n t N u m b e r l a m b s l a m b L a m b L a m b i n g f l ee c e b o d y i n b o d yn u m b e r o f e w e s ~ b o r n b o r n w e a n e d d a t e ~ w e i g h t w e i g h t w e i g h tlb. lb. lb. lb. lb.

    M a t u r e e w e s i n o a t t r ia l1 104 1.28 13.5 88.7 113.9 11.5 148.0 3.62 104 1.25 12.5 80.3 116.7 11.5 146.4 4.93 99 1.45 15.0 98.9 115.4 11.6 147.9 4.44 101 1.41 14.7 95.6 117.0 11.8 149.1 6.95 98 1.49 15.0 95.1 115.7 11.8 145.6 6.86 101 1.40 14.5 89.5 114.8 12.1 148.7 8.37 91 1.42 14.5 93.2 115.5 11.7 146.7 7.98 92 1.28 13.3 88.0 116.6 11.9 148.2 9.3S t d . d e v . .67 6.5 50.2 8.6 1.6 .. .. . 18.9

    M a t u r e e w e s i n a l f a l fa t r ia l1 116 1.29 13.4 85.6 115.7 11.7 147.1 3. 72 110 1.25 12.7 87.2 115.5 11.8 149.3 7.03 113 1.34 14.2 94.2 116.0 11.7 147.7 6.24 108 1.37 13.8 89.0 115.6 12.0 149.3 7.55 105 1.39 14.3 86.2 116.9 12.0 148.3 8.86 106 1,39 14.1 85.7 115.8 11.8 147.6 9.67 107 1.36 14.2 99.0 116.3 12.0 146.4 10.58 108 1.43 14.0 88.6 116.5 11.7 143.4 10.8Std. dev. .70 6.8 51.6 8.3 1.9 .. .. . 7.3

    T w o - y e a r - o l d e w e s i n o a t t ~ a l1 37 .81 8.7 54.0 114.8 10.8 127.5 .82 36 1.14 11.4 73.8 116.8 10.6 128.8 3.73 36 .75 7. 4 48.3 114.8 10.6 125.5 3 .64 37 .81 8.1 45,6 114.3 10.6 129.3 6.15 38 .92 9.5 49.4 116.8 10.5 124.6 3 .56 37 .86 9.2 57.4 114.4 10.9 125.6 5.47 44 .82 8 .4 54.5 115.4 10.8 127.6 4 .98 39 .95 9. 6 62.6 114.8 11.2 130.6 7.2S t d . d e v . ,54 5.3 42.0 9.5 1.1 .. .. . 5.0

    T w o - y e a r - o l d e w e s i n a lf a l fa tr i a l1 35 .83 8. 6 48.2 115.1 10.5 125.8 5.02 36 ,89 8. 8 54.7 116.8 10.6 129.8 5.33 36 ,89 9.2 56.5 117.2 11.0 129.1 5.44 34 1,06 10.8 63.4 115.8 10.8 128.9 5. 55 40 ,95 9.6 54.6 112.8 10.7 128.8 6.76 36 ,83 8.2 53.2 115.1 10.9 127.5 6.67 37 ,89 8. 9 55.3 112.3 10.7 128.8 8.38 34 .97 9.3 59.4 116.4 10.5 129.1 9 .6S t d . d e v . .52 4.9 40.7 10.4 1.3 . . . . . 4 .4a Present at lambing.b D a y o f y e a r .

    a f l u s h i n g p e r i o d o f a p p r o x i m a t e l y 3 w e e k s .H o w e v e r , a ll t h e e w e s r e m a i n e d o n t h e f lu s h in gp a s t u r e f o r p e r i o d s f r o m 2 t o 8 w e e k s a f t e rt h e y s e t t l e d . I t s e e m s p o s s i b l e t h a t t h e t w i n -n i n g r a t e s c o u l d h a v e b e e n h i g h e r a n d c o n -c e p t i o n e a r li er h a d t h e e w e s b e e n r e m o v e df r o m t h e h i g h l e v e l o f n u t r i t io n a t t h e t i m eo f m a t i n g .T e r m i n a t i o n o f f l u sh i n g t r e a t m e n t p r io r t om a t i n g ( t r e a t m e n t s 3 a n d 4 ) d i d n o t s e e m t ol o w e r t h e o v u l a t i o n a n d / o r e m b r y o s u r v i v a lr a t e s r e l a t i v e t o t h e c o n t r o l s a s m e a s u r e db y n u m b e r o f l i v e l a m b s b o r n . I t a p p e a r s t h a t

    a g r e a t e r f l u s h i n g e f f e c t w a s o b t a i n e d i n t h o s ee w e s t h a t w e r e m a t e d a p p r o x i m a t e l y 1 3 t o 1 8d a y s f o l lo w i n g t h e t e rm i n a t i o n o f t h e fe e dt r e a t m e n t t h a n th o s e t h a t p r e s u m e d l y m a t e dt h e fi r st 6 d a y s f o l l o w i n g t h e t e r m i n a t i o n o ft h e f e e d t r e a t m e n t . T h e l a t t e r g r o u p s h o w e dn o m a t e r i a l i n c r e a s e i n l a m b i n g r a t e o v e rt h e c o n t r o l e w e s m a t e d a t t h e s a m e t i m e .B r e e d i n g d a t e s w e r e e st i m a t e d f r o m la m b i n gd a t e s o f e w e s t h a t p r o d u c e d l i v e , fu l l - t e r ml a m b s. T h e d a t a o n l y f r o m e w e s w h i c h w e rea s s u m e d , o n t h i s s a m e b a s i s , t o h a v e m a t e dd u r i n g t h e f ir s t 1 8 d a y s o f t h e b r e e d i n g p e r i o d

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    5 0 8 H U L E T ,s u p p o r t t h e c o n c lu s i o n t h a t t h e e x t e n d e df e e d i ng o f t he s upp l e m e n t i n t r e a t m e n t s 7 a n d8 ha d a n a dv e r s e a f f e c t on r e p r o duc t i on , pos -s i b l y b y i n c r e a s i n g e m b r y o m o r t a l i t y . N o d e -t a i l e d a na l y s i s w a s m a de o f t he s e da t a a ndt h e y a r e n o t p r e s e n t e d s i n c e t h e y c o n s t i t u t e da s e l e c te d s a m p l e . H o w e v e r , c e r t a i n hyp o t he s e sa r e s ugge s t e d , na m e l y : ( 1 ) a c e r t a i n m i n i m u mt i m e i s r e qu i r e d f o r a s upp l e m e n t a l f e e d t op r od uc e a f l u s h i ng e ff e c t a nd t he t i m i ng o fs uc h f e e d i ng m us t p r e c e de s om e de f i n i t e a ndf a i r ly e a r l y p r e o v u l a t o r y p h a se o f t h e o v a r i a nc yc l e , ( 2 ) onc e a fl u s h ing t r e a t m e n t ha s e x -e r ted i t s e f fec t on the de ve lop ing fo l l ic le st he e f f e c t pe r s i s ts u n t i l ovu l a t i on i s c om p l e t e df o r t ha t c yc le ; a nd ( 3 ) p r o l on ge d a dm i n i s t r a -t i on o f t he s upp l e m e n t a l f e e d i s de t r i m e n t a lt o o p t i m u m r e p r o d u c t i v e p e r f o r m a n c e .R e f e r r i n g a ga i n t o f i gu r e 1 i t m a y be ob -s e r ve d t ha t t hos e e w e s w h i c h r e c e i ve d g r a s sh a y p r i o r t o b r e e d i n g c o n s i s t e n t l y h a d l o w e rs u b s e q u e n t l a m b p r o d u c t i o n t h a n t h o s e o n t h es a ge b r us h - g r a s s pa s t u r e ( nu m b e r o f l i ve l a m bsb o r n , P ~ . 0 5 ; l b. l iv e l a m b b o r n , P ~ . 1 0 ; l b.l am b w e an e d , P ( . 1 0 ) . T h i s su g g es ts t h a t t h ec h a n g e i n e n v i r o n m e n t i n c i d e n t t o g o i n g i n t od r y l o t , s e de n t a r i ne s s a nd g r e a t e r i nc r e a s e s i nbo dy w e i gh t , re s u l t e d i n a phy s i o l og i c a l c ond i -t i o n n o t o p t i m u m f o r t h e b e s t s u b s e q u e n t r e -p r o d u c t i v e r a t e .T h e c o r r e l a t i o n s b e t w e e n c h a n g e i n w e i g h td u r i n g t r e a t m e n t a n d n u m b e r o f li v e l a m b sb o r n , p o u n d s o f l iv e l a m b b o r n a n d p o u n d so f l a m b s w e a n e d o b t a i n e d f r o m t h e e n t i r eg r oup o f m a t u r e e w e s on t he oa t t r i a l ove r a l lt r e a t m e n t s w i t h i n b r e e d s a n d y e a r s ; a n dw i t h i n t r e a t m e n t s , b r e e ds a nd ye a r s w e r e 0 . 03 ,

    E T A L .0 . 05 a nd 0 . 01 ; a nd 0 . 03 , 0 . 04 a nd - - . 0 2 ,r e s pe c t i ve ly . T h i s a g r e e s w i t h r e s u l t s ob t a i ne db y F o o t e et a l . ( 1959 ) bu t i s i n d i s a g r e e m e n tw i t h r e s u l t s o b t a i n e d b y H o v e r s l a n d ( 1 9 5 8 ) ,T e r r i l l a n d S t o e h r ( 1 9 3 9 ) a n d M a r s h a l l a n dP o t t s ( 192 4 ) w ho f ound pos i t i ve a s s oc i a ti onbe t w e e n ga i n i n w e i gh t du r i ng b r e e d i ng a nds u b s e q u e n t l a m b p r o d u c t i o n . T w o r e a s o n s f o rt he s e low c o r re l a t i ons a r e : ( 1 ) t he e w e s ons a ge b r us h - g r a s s pa s t u r e p r i o r t o b r e e d i ngg a i n e d t h e l e a s t w e i g h t d u r i n g t r e a t m e n t y e th a d t h e h i g h e s t s u b s e q u e n t l a m b p r o d u c t i o na nd ( 2 ) l a m b p r od uc t i on e xh i b i t s a c u r v i l i ne a rr e l a t i ons h i p w i t h t i m e r e l a t i ve t o t he l e ng t ho f t he f l u s h ing pe r i od , w he r e a s c ha nge i n bo dyw e i gh t i s l i ne a r l y r e l a t e d w i t h t i m e .

    S u m m a r yA p p r o x i m a t e l y 1 2 0 0 C o l u m b i a a n d T a r g h e ee w e s w e r e r a ndom i z e d w i t h i n a ge a nd b r e e d i ngp e n i n t o e i g h t t r e a t m e n t g r o u p s i n w h i c h s u p -p l e m e n t a t i on w i t h 0 . 7 l b . o f oa t s f o r va r y i ngl e ng t h s o f t i m e be f o r e a nd du r i ng b r e e d i ngw e r e c om pa r e d . A n i de n t i c a l e xpe r i m e n t w a sc onduc t e d u s i ng 1 l b . o f a l f a l f a pe l l e t s a s as upp l e m e n t i n l i e u o f oa t s on a c om pa r a b l eg r o u p o f e w e s . O a t s u p p l e m e n t a t i o n h a d as i gn i f ic a n t e f fe c t ( P ~ . 1 0 ) i n m a t u r e e w e s o n

    num be r o f l i ve l a m bs bo r n , pounds o f l i vel a m b b o r n , a n d p o u n d s o f la m b w e a n e d . T r e a t -m e n t m e a ns va r i e d f r om 1 . 25 t o 1 . 49 f o rnu m be r of l ive l amb s born , 12 .5 to 15 .0 lb . o fl i ve l a m b bo r n , a nd 80 .3 t o 98 . 9 l b . o f l a m bw e a ne d pe r e w e p r e s e n t a t la m b i ng . A s ho r tf l u sh i ng pe r i od ( 17 da ys ) i m m e d i a t e l y p r i o rt o b r e e d i n g i n c r e a s e d l a m b p r o d u c t i o n o v e rTABLE 3. MEAN S EPARATION TESTS OF SIGNIFICANCE" FOR TREAT MENT EFFECTSON AVERAGE LAMB PRODUCTION OF MATURE EWES ON THE OAT TRIAL

    Num ber of live lambs bo rnTrea tmen t numb er 2 1 8 6 4 7 3Mea n 1.25 1.28 1.28 1.40 1.41 1.42 1.46 1.49Significance

    Treatment number 2 8Mea n 12.49 13.27Significance

    Treatment number 2 8Mean 80.3 88.0Significance

    Pounds of live lamb born1 6 7 4 5 313.53 14.49 14.52 14.71 14.77 15.00

    Pounds of lamb weaned1 6 7 5 4 3

    88.7 89.5 93.2 95.1 95.6 98.9

    a Duncan's (1957) multiple range test. Means underscored by the same line do not differ significantly (P

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    FLUSHING ON LAMB PRODUC TION 509

    1 . 5 [ 0 0 ~ I 0_1vZ O

    n , - W 90 Z I -n n < ~ 9 5 T

    1 . 4 _ ~ : , , ,~ m 7= J ~ [ - Ot .~ ._ I o

    _ n n 6- - L I -._1 on - " 1 .3 _u . I r 5

    , ~ ~ [~D i 0Z I n r r 4I 8 C Z1 . 2 4 6 : 6 3

    0 1 7 3 4 . I 0 ' 7 3 4 5 1 0 1 7 5 4 - 5 1S U P P L E M E N T A L F E E D I N G P E R I O D ( D A Y S )

    Figure 1. The effect of length of supplemental feeding period and pre-breeding management onlamb production and body weight (dur ing the exper imental period) of mature ewes (oat trial).Shaded bars indicate results for ewes managed on sage=brush=grass pasture prior to breeding;unshaded bars indicate results for ewes fed grass hay in dry=lot for 17 days prior to breeding.Numbers inside the bars refer to treatments. Breeding commenced on the 17th day of treatment.Most ewes conceived between the 17th and 34th day o~ the trial.the controls. Extending this period an addi-tional 17 days during breeding produced nofurther increase in production but increasedcosts. A further 17-day extension caused anapparent production decline from that ob-tained by shorter flushing periods. Ewes onnative grass hay for 17 days prior to breedinghad lower lamb production than those on dry,native pasture. Alfalfa pellets had an appar entbut nonsi gnific ant flushing effect on la mb pro-duction in mature ewes. Neither oats noralfalfa pellets had significant flushing effectson 2-year-old ewes. Both oat and alfalfa pelletsupplementation significantly increased bodyweight during treatmen t in mature and 2-year-old ewes. Change in body weight during treat-ment was not significantly correlated withlamb production.

    L i t e r a t u r e C i te dCampbell, F. R., ][. H. Jones and W. T. Hardy. 1959.Response of range ewes to flushing. Tex. Agr. Exp.Sta. Prog. Rpt. 2111.Clark, R. T. 1935. Studies on the physiology of re-production in the sheep. Anat. Rec. 60:126.Darlow, A. E. 1942. Effect of plane of nutrition onreproductive processes in the ewe. Ph.D. Thesis.University of Wisconsin, Madison, Wisconsin.Darroch, J. G., A. W. Nordskog and J. L. Van Horn.1950. The effect of feeding concentrates to rangeewes on lamb and wool productivity. J. AnimalSci. 9:431.Duncan, D. B. 1957. Multiple range tests for corre-lated and heteroscedastic means. Biometrics 13:164.El Sheikh, A. S., C. V. Hulet, A. L. Pope and L. E.Casida. 1955. The effect of level of feeding on thereproductive capacity of the ewe. J. Animal Sci.14:919.Foote, W. C., A. L. Pope, A. B. Chapman and L. E.Casida. 1959. Reproduction in the yearling ewe as

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    H e a p e , W . 1 8 99 . A b o r t i o n , b a r r e n n e s s a n d f e r t i l i t yin sh e e p . J . Re s . Ag r . So c . 6 0 :2 1 7 .H e n d e r s o n , C . R . 1 9 60 . D e s i g n a n d a n a l y s i s o f a n i m a lh u s b a n d r y e x p e r i m e n t s . T e c h n i q u e s a n d P r o c e d u r e si n A n i m a l P r o d u c t i o n R e s e a r c h . A m e r i c a n S o c i e t yo f A n i m a l P r o d u c t i o n . p . 2 - 5 4.Ho v e r s l a n d , A. S . 1 9 5 8 . Th e e f f e c t o f f l u sh in g o n r e -p r o d u c t i v e p e r f o r m a n c e o f e w e s m a n a g e d u n d e rr a n g e c o n d i t i o n s . M . S . T h e s i s . M o n t a n a S t a t e C o l -l e g e , B o z e m a n , M o n t a n a .H o v e r s l a n d , A . S ., J . L . V a n H o r n , O . O . T h o m a sa n d F . A . B r a n s o n . 1 9 5 6 . R e p r o d u c t i o n o f r a n g ee w e s a s i n f l u e n c e d b y s u p p l e m e n t a l f e e d i n g p r i o rt o a n d d u r i n g b r e e d i n g . P r o c . W e s t . S e c . A m . S o c .A n . P r o d . 7 : ( L I I I ) 1 .M a r s h a l l , F . H . A . 1 9 0 8 . F e r t i l i t y i n S c o t t i s h s h e e p .Tra n s . Hig h l . Ag r . So c . Sc o t l a n d 2 0 :1 3 9 .M a r s h a l l , F . H . A . a n d C . G . P o r t s . 1 9 2 4 . F l u s h i n g

    a n d o t h e r m e a n s o f i n c r e a s i n g l a m b y i e ld . U . S . D .A .Bul . 996 .N i c h o l s , J . E . 1 9 2 6. F e r t i l i t y i n S o u t h d o w n s h e e p.J . M i n i s t r y A g r . 1 6 : 3 6 5 .R o b e r t s o n , G . L ., L . E . C a s id a , R . H . G r u m m e r a n dA . B . C h a p m a n . 1 9 5 1 . S o m e f e e d i n g a n d m a n a g e -m e n t f a c t o r s a f fe c t i n g a g e a t p u b e r t y a n d r e l a t e dp h e n o m e n a i n C h e s t e r W h i t e a n d P o l a n d C h i n ag i l ts . J . A n im a l Sc i. 1 0 :8 4 1 .S e l f , H . L . , R . H . G r u m m e r a n d L . E . C a s i d a . 1 9 5 5 .T h e e f f e c t s o f v a r i o u s s e q u e n c e s o f f u l l a n d l i m i t e df e e d i n g o n t h e r e p r o d u c t i v e p h e n o m e n a i n C h e s t e rW h i t e a n d P o l a n d C h i n a g i l t s . J . A n i m a l S c i .1 4 :5 7 3 .S n e d e c o r , G . W . 1 95 9. S t a t i s t i c a l M e t h o d s ( 5 t h e d . ) .T h e I o w a S t a t e C o l l e g e P r e s s , A m e s , I o w a .T e r r i l l , C . E . a n d J . A . S t o e h r . 1 9 3 9 . R e p r o d u c t i o ni n r a n g e s h e e p . P r o c . A m . S o c . A n . P r o d . , 3 2 n dA n n . M e e t . 3 6 9 .W a l l a c e, L . R . 1 95 4. S t u d i e s i n t h e a u g m e n t a t i o n o ff e r t i l i t y o f R o m n e y e w e s w i t h p r e g n a n t - m a r eseru m. J . Agr . Sc i . 45 : 60 .W i l l ia m s , S . M . 1 9 ff4 . Fe r t i l i t y i n C lu n Fo re s t sh e e p .J . Ag r . Sc i . 4 5 :2 0 2 .

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    Citations

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