Milk Iodine as Influenced by an Iodophor Teat Dip

8/4/2019 Milk Iodine as Influenced by an Iodophor Teat Dip

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M i l k I o d i n e a s I n f lu e n c e d b y a n Io d o p h o r T e a t D i p 1 ,2L . M . C O N R A D , i l l , an d R . W . H E M K E ND e p a r t m e n t o f A n i m a l S c ie n ce sU n i v e r s i t y o f K e n t u c k yL e x i n g t o n 4 0 5 0 6

A B S T R A C TW e q u a n t i t a t e d t h e i n c r e a s e o f i o d i n e

i n m i l k f r o m i o d o p h o r t e a t d i ps a n dd e t e r m i n e d t h e m o d e b y w h i c h t h a t i o-d i n e e n t e r e d t h e m i l k . I n o n e t r i a l w i t ht e a t d i p p i n g f o r 1 w k , i o d i n e i n m i l k i n -c r e a s e d 8 . 8 u g / 1 0 0 m l . I n a n o t h e r t r i a l,o n l y r i g h t u d d e r h a lv e s w e r e d i p p e d w i t ht h e i o d o p h o r . S a m p l e s o f m i l k f r o m t h el e f t u d d e r h a l f i n c r e a s e d i n i o d i n e c o r r e s -p o n d i n g t o t h e r i g h t u d d e r h a l f o n l ys l i g h t l y le ss . T i n c t u r e o f i o d i n e w a s a p -p l ie d t o t h e s k i n b e t w e e n t h e v u l v a a n dt h e p o i n t o f u d d e r a t t a c h m e n t o f c ow s .S a m p l e s o f m i lk f r o m t h e g r o u p w i tht i n c t u r e i n c re a s e d m a r k e d l y i n i o d i n ec o n t e n t o v e r th e c o n t r o l g r o u p . I o d o p h o rt e a t d i p s i n c r e a s e d t h e i o d i n e i n m i l k b y8 t o 1 0 u g / 1 0 0 m l . T h e p r i m a r y m o d e o fi n c re a s e d i o d i n e a p p e a r s t o b e a b s o r p t i o nt h r o u g h t h e s k i n a n d e n t r y i n t o t h e m i l kb y t h e m i l k s y n t h e s i s p ro c e s s r a t h e r t h a nb y c o n t a m i n a t i o n f r o m t h e t e a r ' s su r f ac e .

I N T R O D U C T I O NI o d o p h o r s h a v e b e c o m e i n c r e a s i n g l y p o p u -

l a r a s a b a c t e r i o s t a t i c a g e n t a g a i n s t m a s t i t i co r g an i sm s . T h e u s e o f i o d o p h o r t e a t d i p s h asi n c r e a s e d m i l k i o d i n e c o n t e n t ( 4 , 8 , 9 , 1 0 , 1 4 ) .E v i d e n c e w a s p r e s e n t e d ( 5 ) o f in c r e a s e d i o d i n ec o n s u m p t i o n o f h u m a n b e i n g s d u e t o c h a n g in gc o n s u m p t i o n h a b i t s a n d a d v a n c e d t e c h n o l o g i -c a l p r a c t i c e s i n a n i m a l a g r i c u l t u re , f o o d p r o c e s -s i n g , a n d p r e s e r v a t i o n . T h e r e i s c o n c e r n t h a tp e o p le m a y b e c o n s u m i n g t o o m u c h i o d in e .G o i t r o u s f o a l s h a v e b e e n b o r n t o m a r e s i n ge s -

t in g l a r g e a m o u n t s o f i o d in e i n se a w e e d k e l p( 2 ). A l s o , b a b ie s b o r n t o a s t h m a t i c m o t h e r su s in g i o d i d e e x p e c t o r a n t s o v e r p r o l o n g e d t i m eh a v e e n l a r g e d t h y r o i d s ( 1 3 ) . B e g g a n d H a l l ( 3 ),W o l f f ( 1 8 ) , a n d H a r r i s o n ( 7 ) c i t e s i m i l a r m e d i -c a l c a se s i n v o l v in g i o d i n e m e d i c a t i o n s .

T h e o b j e c t i v e s o f th i s s t u d y w e r e t o q u a n -t i ta t e t h e a m o u n t o f i o d in e f r o m t e a t d ip t h a tg e t s in t o m i l k a n d t o d e t e r m i n e c e r t ai n m a n a g e -m e n t f a c t o r s t h a t m i g h t a f f e c t t h e a m o u n t o fi o d i n e f r o m t e a t d i p t h a t g e t s i n t o t h e m i l k .

M A T E R I A L S A N D M E T H O D SA s e ri es o f e x p e r i m e n t s c o m p a r e d e f f e c ts o f

a n i o d o p h o r t e a t d i p w i t h a c h l o r i n e t e a t d i p o nt h e i o d i n e o f m i l k . M i l k s a m p l e s f r o m w e i g hj a rs w e r e c o l l e c t e d a t v a r y i n g i n t er v a l s d e p e n d -i n g u p o n t h e e x p e r i m e n t a l d e s i g n . S a m p l e s f i rs tw e r e d e f a t t e d b y c e n t r if u g a t i o n a t a b o u t 3 0 0 0r p m f o r 5 ra i n . D e f a t t e d f l u i d m i l k w a s a n a l y -z e d f o r io d i n e s in c e t h e b u t t e r f a t f r a c t i o n c o n -t a i n s l i t t l e i o d i n e ( 1 2 ) . T o t a l i o d i n e a n a l y s i s w a sb y T e c h n i c o n A u t o a n a l y z e r ( 1 6 ) f o ll o w i ngt h e m e t h o d o u t l i n e d f o r p r o t e i n - b o u n d i o d i n ei n b l o o d s e r u m , e x c l u d i n g t h e r e si n t r e a t m e n ts t e p t o r e m o v e i n o r g a n i c i o d i n e . I n t h i s p r o c e d -u r e , t h e s a m p l e f i r s t w a s d i g e s t e d a u t o m a t i c a l l yi n a m i x t u r e o f n i tr i c a n d p e r c h l o r i c a c i d a n da n a l y z e d f o r i o d i n e b y it s c a t a l y t i c e f f e c t o nt h e r e d u c t i o n o f e e r i e i o n b y a r s e n i o u s a c i d .R e d u c t i o n o f t h e c e ri c io n w a s r e c o r d e d a s re a dw i t h a s p e c t r o p h o t o m e t e r .

A v a i l a b l e i o d i n e i n t h e i o d o p h o r t e a t d i p i sin t h e f o r m o f n o n y l p h e n o x y p o l y e t h o x ye t h a n o l - i o d i d e c o m p l e x ( p r o v i d i n g 1% t i t ra t a -b l e i o d i n e ) , 1 1 .2 % o f t h e t o t a l m i x t u r e .

R e c e i v e d N o v e m b e r 23, 1977.1This manuscript (77-5-192) is published with theapprova l o f the Director of the K entuck y Agricul turalE x p e r i m e n t Station.2Data in this p a p e r a r e f r o m t h e t h e s i s o f thesenior author, submitted to the Graduate School ofthe University of Kentucky in partial fulfillment ofthe requirement for the M.S. degree.

E x p e r i m e n t II n t h r e e g r o u p s o f si x H o l s te i n c o w s t h e e f -

f e c t o f u d d e r w a s h i n g a s o p p o s e d t o n o u d d e rw a s h i n g p r io r t o m i lk i n g o n m i l k i o d i n e c o n t e n tw a s m e a s u r e d w i t h a n i o d o p h o r t e a t d i p a s ap o s t m i l k in g t r e a t m e n t . T h e t e a t d i p p in g w a s b ya n e x t r a m a n i n t h e m i l k i n g p i t i n a d d i t i o n t o

1978 J Dai ry Sc i 61 :77 6-7 80 776


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I ODINE I N MI LK FR OM TEAT DI P 7 7 7t h e r e gu l ar m i l k m a n . T e a t d i p p i n g c o m m e n c e da f t e r t h e c o n t r o l s a m p l e w a s t a k e n , d e s i g n a t e da s d a y 1. S a m p l e s t h e n w e r e c o l l e c t e d o n d a y 3w i t h f iv e m i l k in g s b e t w e e n s a m p l e s .

T e a t s o f t h e t w o e x p e r i m e n t a l g r o u p s w e r ed i p p e d w i t h i o d o p h o r t e a t d i p , o n e g r o u ph a v in g t h e u d d e r w a s h e d w i t h w a t e r ( n o a d d i -t iv e ) p r i o r t o m i l k i n g w h i le t h e o t h e r g r o u p w a sn o t w a s h e d b u t w a s m a s s a g e d o n l y t o s t i m u l a t el e t - d o w n o f m i l k . T h e t h i r d g r o u p s e r ve d a s ac o n t r o l , a n d t h e i r t e a t s w e r e d i p p e d w i t hc h l o r i n e s o l u t i o n .

E x p e r i m e n t I IT w e l v e H o l s t e in c o w s w e r e a s s ig n e d in t o t w og r o u p s o f s i x , a n d t h e i r t e a t s w e r e d i p p e d w i t h

e i t h e r c h l o r i n e o r a n i o d o p h o r s o l u t i o n o v e r 8d a y s . S a m p l e s w e r e c o l l e c t e d f r o m t h e fi r s tt h r e e m i l k in g s ( d a y s 1 a n d 2 ) a s p r e t r e a t m e n tc o n t r o l s w h i l e a l l c o w s ' t e a t s w e r e b e i n g d i p p e di n c h l o r i n e s o l u t i o n . T e a t d i p p i n g w i t h t h ei o d o p h o r c o m m e n c e d a t t h e e ve n in g m i l k in g o nd a y 2 . M i l k sa m p l e s w e r e c o l l e c t e d e v e r y 2 n dd a y ( d a y s 3 , 5 , 7, a n d 9 ) a t t h e m o r n i n g a n de v e n in g m i l ki n g s . S a m p l e s o f m o r n i n g a n d e v e n -i n g m i l k w e r e c o m b i n e d . A l l u d d e r s w e r ew a s h e d w i t h w a t e r n o t c o n t a i n i n g a n y u d d e rw a s h s o l u t i o n .E x p e r i m e n t I I I

T h e t h i r d e x p e r i m e n t w a s d e s i g n e d t o d e t e r-m i n e t h e m o d e o f a c t io n b y w h i c h i o d i n ee n t e r s t h e m i l k , b y c o n t a m i n a t i o n o r a b s o r p -t i o n , a s w e ll a s t o d e t e r m i n e t h e e x t e n t o fc o n t a m i n a t i o n o r ab s o r p t io n . T w o g r o up s o ff o u r c o w s e a c h w e r e u s e d , o n e g r o u p s e r v in g a st h e c o n t r o l h a v i n g t h e i r t e a t s d i p p e d w i t hc h l o r i n e s o l u t i o n . O n l y t h e t e a t s o n r ig h t u d d e rh a l f o f t h e t e s t g r o u p w e r e d i p p e d w i t h t h e i o -d o p h o r t e a t d i p ; t h e o t h e r t e a ts w e r e d i p p e dw i t h t h e c h l o r i n e s o l u ti o n . S a m p l e s f r o m t h et e s t g r o u p ( l e ft a n d r i g h t h a l f o f u d d e r ) w e r et a k e n b y h a n d m i l k i n g a f te r t h e u d d e r w asw a s h e d a n d a s t r i p c u p u s e d . C o m p o s i t e s a m -p l e s w e r e t a k e n f r o m t h e w e i g h j a r . T h e f i r s tt w o s a m p l e s w e r e t a k e n o n c o n s e c u t i v e d a y s , 1a n d 2 , b e f o r e t e a t d i p p i n g b e g a n a n d w e r e u s e da s p r e t r e a t m e n t c o n t r o l s. A d d i t i o n a l s a m p l i n g so c c u r r e d o n d a y s 4, 7 , 1 1 , 1 5 , 1 8 , 21 , a n d 2 4 .T h e s a m p l i n g t o o k p l a c e o v e r 2 4 d a y s t o s h o wt h e p o i n t o f m a x i m a l a b s o r p t i o n .

E x p e r i m e n t I VT h i s e x p e r i m e n t w a s d e s i g n e d t o p r o v i d e ad -

d i t i o n a l e v id e n c e o f t h e a b s o r p t i o n h y p o t h e s e s .G r o u p s o f s ix c o w s w e r e a s s ig n e d t o t w o t r e a t -m e n t s , 1 ) t i n c t u r e o f i o d i n e a p p l i c a t i o n t o t h es k i n ( th e a r e a b e t w e e n t h e p o i n t o f u d d e r a t-t a c h m e n t a n d t h e v u l v a) ; t e a t s o f t h i s g r o u pw e r e d i p p e d w i t h t h e c h l o r i n e s o l u t io n , a n d 2 )c o n t r o l o r c h l o r i n e t e a t d i p o n l y . A s p r e v i o u s l yd e s c r i b e d , t w o s a m p l e s w e r e t a k e n o n d a y s 1a n d 2 a s p r e t r e a t m e n t c o n t r o l s a m p l e s b e f o r et r e a t m e n t w a s i n i t i a te d . B l o o d s a m p l e s w e r et a k e n o n d a y s 1 a n d o n d a y s 1 1 a n d 1 5 . M i l ks a m p l e s , o t h e r t h a n c o n t r o l , w e r e t a k e n o n d a y s6 , 1 1 , a n d 1 5 . S a m p l e s , b o t h m i l k a n d b l o o d ,w e r e t a k e n a t e v e n in g m i lk i n g s. T r e a t m e n ts t a r t e d o n d a y 3 .

T h e t i n c t u r e o f io d i n e w a s a p p l i e d o n c ed a i l y b y s p r a y i n g t h e s k i n w i th a p u m p - t y p ew i n d o w c l e a n e r b o t t l e . T i n c t u r e o f i o d i n e a p -p l i c a t i o n s t o p p e d o n d a y 1 1 t o d e t e r m i n e t h et i m e f o r t h e m i l k to r e t u r n t o n o r m a l . B l o o ds a m p l es w e re f r o m t h e s u b c u t a n e o u s a b d o m -i n a l v e i n .

A l l d a t a w e r e s u b j e c t e d t o a n a l y s i s o f v a r i -a n c e a s d e s c r i b e d b y S n e d e c o r ( 1 5 ). S a m p l e sf r o m t h e p r e t r e a t m e n t p e r i o d w e r e u s e d t o c o r-r e c t f o r i n d i v i d u a l d i f fe r e n c e s . D i f f e r e n c e s b e -t w e e n t h e c o n t r o l p e r i o d a n d t h e e x p e r i m e n t a lo r t e s t p e r i o d w e r e s u b j e c t e d t o a n a l y s is o fv a r i a n c e .

R E S U L T S A N D D I S C U S S I O NE x p e r i m e n t I

E x p e r i m e n t I w as p r o p o s e d t o d e t e r m i n e ifp r e m i l k i n g m a n a g e m e n t p r a c t ic e s , i .e ., u d d e rw a s h i n g a s o p p o s e d t o n o u d d e r w a s h , i n fl u -e n c e s t h e i o d i n e c o n t a m i n a t i o n i n m i l k d u e t oi o d o p h o r t e a t d i p .

T h e d i f f e r e n c e b e t w e e n t h e w a s h a n d n ow a s h g r o u p s ( T a b l e 1 ) , w a s o n l y . 7 u g / l O 0 m l .D i f fe r e nc e s b e t w e e n t h e t w o i o d o p h o r d i p p e dg r o u p s a n d t h e c o n t r o l g r o u p s w e r e s ig n i f ic a n ta t 1 %. T h e i n s i g n i f i c a n t d i f f e r e n c e d u e t o w a s hv e r s u s n o w a s h i s a n i n d i c a t i o n i o d i n e is n o tw a s h e d o f f t h e u d d e r , a n d , m o s t l i k e l y , t h e i n -c r e a s e i s n o t d u e t o c o n t a m i n a t i o n b u t p o s s i b l yd u e t o a b s o r p t i o n t h r o u g h t h e t e a t t is s u e a n dr e - e n t r y i n t o t h e m i l k f r o m t h e b l o o d b y t h em i l k s y n t h e s i s p r o c e s s.

T h e r e s u lt s i n d i c a t e n o d i f f e re n c e b e t w e e nJournal of Dairy Science Vol. 61, No. 6, 1978


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7 7 8 C O N R A D A N D H E M K E NT A B L E 1 . A v e r a g e io d i n e i n m i l k ( /~g /1 0 0 m l ) w i t h d i f f e r e n t p r e m i l k in g t r e a t m e n t s .

T r e a t -C o n t r o l m e n tT r e a t m e n t D a y 1 D a y 3 Dif fe r -e n c e cIodo pho r , wash 15 .1 20 .3 4 .8 aIodo pho r , no wash 12 .8 18 .4 5 .6 aCo nt ro l 15 .2 16 .4 1 .2 b

a 'bMeans wi th d i f f e ren t supe r sc r ip t s d i f f e r (P< .01) .CS ix c o w s p e r t r e a t m e n t , s t a n d a r d e r r o r o f m e a n . 78 .

p r e m i l k i n g h y g i e n e r o u t i n e s a s s u g g e s t e d b yI w a r r s o n a n d E k m a n ( 8 ), i n d i c a t i n g t h a t i o d i n ec o n t a m i n a t i o n i n m i l k is n o t d u e t o t h e a m o u n to f d i s i n f e c t a n t r e m a i n i n g o n t h e t e a t s f r o m t h ef o r e g o i n g m i l k in g . A l s o , th e i o d i n e i n m i l k d i dn o t r e a c h a m o u n t s f r o m b u l k t a n k m i l k sa m p l e sr e p o r t e d b y r e s e a r c h e r s ( 9, 1 0 ) , i n d i c a t i n g t h a tt h e m a x i m u m i o d in e in m i lk h a d n o t b e e na t t a i n e d o r t h e t e a t d i p i t s e l f d i d n o t p r o v i d e asm u c h i o d i n e t o c o n t a m i n a t e t h e m il k . O t h e rf a c t o r s s u c h a s s e a s o n ( 6 ) o r s ta g e o f l a c t a t i o n( 1 7 ) m i g h t e x p l a i n s u c h d i f fe r e n c e s ; h o w e v e r ,t h e l e n g t h o f e x p o s u r e o f t h e c o w s t o t h e t e a td i p is t h e m o s t l o g ic a l e x p l a n a t i o n .

E x p e r i m e n t I IT h i s e x p e r i m e n t w a s t o d e t e r m i n e t h e c o n -

t e n t a t w h i c h m i l k i o d i n e w o u l d s t o p i n c r e a si n g

26, ~ ~ r i g h t u d d e r h a l fo - - o L eft u dd er h al f ~ &0 - - 0 C O ~ P O I iI : s l : "

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. ; ~ , " , " , ~ , S a m p l e D a y s

FI G . 1 . I n f l u e n c e o f a n i o d o p h o r t e a t d i p o n m i l ki o d i n e a s c o m p a r e d w i t h a n o n i o d i n e t e a t d i p . S i xc o w s p e r t r e a t m e n t w i t h s t a n d a r d e r ro r o f t r e a t m e n tm e a n o f 1 .0 9 .

d u e t o i o d o p h o r t e a t d ip a n d t o d e t e r m i n e t h et i m e t o r e a c h l e v e l i n g p o i n t . T e a t d i p p i n g w a sm a i n t a i n e d o v e r 8 d a y s t o a c h i e v e t h e l e v e li n go f i n c r e a s e d m i l k i o d i n e f r o m t e a t d ip . A t t h ee n d o f 8 d a y s ( F i g . 1 ), m i l k i o d i n e i n c r e a s e d5 .7 ~ g / 1 0 0 m l o v e r t h e p r e t r e a t m e n t a v e r a g ew h i l e th e c o n t r o l g r o u p d e c r e a s e d 2 . 9 u g / 1 0 0m l f r o m p r e t r e a t m e n t .

A s h a d h a p p e n e d i n a l m o s t a l l o f t h e s e s tu -d ie s , t h e i o d i n e i n m i l k o f th e c o n t r o l g r o u p u s -u a l l y w a s i n c r e a si n g , d e c r e a s i n g , o r f l u c t u a t i n g .S i n c e a l l s a m p l e s w e r e a n a l y z e d i n t h e l a b o r a -t o r y a t t h e s a m e t i m e a n d i n d i v i d u a l s w i t h i n ag r o u p c h a n g e d t o g e t h e r , t h e d a y - t o - d a y f l u c t u a -t i o n s i n m i l k i o d i n e w e r e r e a l. T h e s p r e a d b e -t w e e n t h e t w o g r o u p s i n c re a s e d f r o m 4 . 6 t o 5 . 4t o 7 . 3 t o 8 . 6 / ~ g / m l b y s a m p l e d a y . T h e c o n t i n -u i n g i n c r e a s e i n i o d i n e o f m i l k i n d i a t e s t h a t a d -s o r p t i o n m a y n o t h a v e r e a c h e d i ts m a x i -m u m . S t a t i s ti c a l a n a ly s i s d o e s s h o w d i f f e r e n c e sd u e to t r e a t m e n t a n d t i m e b y t r e a t m e n t w i thP < . 0 1 .

2O

0

, , ~ t e a t d i p i n i t i a t e di i i i i il ~ 3 5 7 9

S a m p l e D a y s

FI G . 2 . l o d i n e o f m i l k f r o m c o w s w h o s e r ig h t si d et e a t s w e r e d i p p e d w i t h a n i o d o p h o r t e a t d i p c o m p a r e dw i t h a c o n t r o l g r o u p w h o s e t e a t s w e r e d i p p e d i n anon iod ine tea t d ip . S ix cows a ssigned to each t r ea t -m e n t w i t h s t a n d a rd e r r o rs f o r t r e a t m e n t m e a n o f 3 .2 7f o r m i l k s a m p l e s f ro m u d d e r h a l v e s a n d . 7 3 f o r c o m -p o s i t e a n d c o n t r o l c o m p a r i s o n .

J o u r n a l o f D a i r y Sc i e n c e V o l . 6 1 , N o . 6 , 1 9 7 8


4/5

IODINE IN MILK FROM TEAT DIP 779TABLE 2. Iodine of milk (/ag/lO0 mI) and of plasma (/~g/100 ml) resulting from application of tincture ofiodine.

Pre-t r e a t -men t Post-avg. treat-Days 1 Treatment period merit

Treatment and 2 Day 6 Day 11 Day 16Milk samplesTincture of I 3.5 21.3 a 6.7 4.7Control 3.5 4.2 5.3 4.9Plasma samplesTincture of I 5.8 .. 8.4 b 5.2Control 5.8 . . . 5.0 5.0

aMilk iodine content P


5/5

780 CONRAD AND ItEMKEN

of 18.4 ug/100 ml for bulk tank milk sampleswhen teats were dipped for 2 wk. However ,they did not use control cows at the same t ime.Connal ly (4) and Joer in and Bowering (10)arenear agreement , report ing ranges of 11.3 to34.6 ug/ 100 ml and 1 to 75 ug/l O0 ml of in-creased iodine in milk. The difference betwe enthe products , extent of appl icat ion, and designof experiments are probable reasons for thevariat ion between s tudies .

The exp eri ment involving t incture of io-dine to th e skin, coup led wi th th e gradual in-crease in milk iodine in ot her stu dies, indicat esthat iodine is absorbed into the cow's systemand secreted into the milk.

A C K N O W L E D G M E N T SThis research was supported in par t by Eco-

nomics Laboratory, Inc.

R E F E R E N C E S1 Alderman, G., and M. H. Stranks. 1967. The iodinecontent of bulk herd milk in summer in relation toestimated dietary intake o f cows. J. Sci. Fd. Agr.

18:151.2 Baker, H. J., and H. R. Lindsey. 1968. Equinegoiter due to excess dietary iodide. J. Amer. Vet.Med. Ass. 153:1618.3 Begg, T. B., and R. Hall. 1963. Iodide goiter andhypert hyroid ism. Quart. J. Med. 32:351.4 Connally, R. J. 1971. The changing iodine environ-ment o f Tasmania. Med. J. Aust. 2:1191.5 Fisher, K. D., and C. J. Carr. 1974. Iodine inFoods: Chemical methodology and sources of i o -

dine in the human diet. FASEB (FDA 71-294).6 Garner, R. J., B. F. Swanson, and H. G. Jones.1960. Fission produc ts and the dairy cow. I11.Transfer of 1131 to milk following single and dailydosing. J. Agr. Sci. 55:283.7 Harrison, M. T., W. D. Alexander, and R. MeG.Harden. 1963. Thyroid function and iodine metab-olism in iodine induced hyperthyroid. Lancet 1:1238.8 lwarrson, K., and L. Ekman. 1973. The effect of apost milking teat dip on the iodine concentrationof bulk herd milk. Acta Vet. Scand. 14:338.9 lwarrson, K., and L. Ekman. 1974. Iodophor teatdipping and the iodine concentration of milk.Nord. Vet.-Med. 26: 31.10 Joerin, M. M., and A. Bowering. 1972. Total iodinecon ten t of cow's milk. New Zealand. J. Dairy Sci.Technol. 7:155.11 Kalkus, J. W. 1920. A study of goiter and associa-ted conditions in domestic animals. Wash. Exp.Sta. Bull. 156.12 Lengemann, F. W., and E. W. Swanson. 1957. Astudy of the secretion of iodine in milk of dairycows, using daily oral doses of 113~. j. Dairy Sci.40:216.13 Packard, G. E., E. T. Williams, and S. E. Whellock.1960. Congenital constructing goiter. Surgery 48:422.14 Schumacher, E. 1975. Contamination of milk byiodine and nonoxinol due to teat dipping in Lora-sol CCT. Milchwissenschaft 30:333.15 Snedecor, G. W. 1946. Statistical methods. 4th ed.

Iowa Sta te University Press.16 Technicon Autoanalyzer Methodology. 1965.Technicon Laboratory Method File N-56. Techni-con Instruments Corp. Chauney, New York.17 Underwood, E. 1971. Page 281 in Trace elementsin human and animal nutrition. 3rd Edition.Chapter 11. Academic Press, New York, 1971.18 Wolff, J. 1964. Iodide goiter and the pharmacolog-ical effects of excess iodide. Amer. J. Med. 47:101.

Journal of Dairy Science Vol. 61, No. 6, 1978

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Milk Iodine as Influenced by an Iodophor Teat Dip