Peruanos, para el año
11. Conclusiones y Recomendaciones
( a ) ( b)
(cl
3 . 0 -3 0 0 - """'2"-- - - --Q ---£"""
-b-l_
... ...l-- - -
- ... .._ +3 0 +60 +90 + 1 20 +150 + 1 80T i me from i nfusion ( m i nute s )
Figure
24
P
lasm
alevel s o � Glu c o se , insul i n , ( c )
growth hormone and ( d ) prolactin. Mea n for
values o btai ned on sa l i cyla te tre a tment days
( soli d line s ) and on c ontrol days (broken
line s ) . Vert ical l i ne s r e pre sent s t a nda rd
e rror or the mean, ba se d on variance between calves within d ifferent sampling day s.
mea n value s of �l uco se ,
insulin, GH and prol ac t i n i n pla sma ror
di fferent sample t ime s on day s o f sa l i cyla t e a n d sa line t r e a tme n t . Samples mg /100 ml I n sulin 1o pg Jrnl : pg /ml in parenthe se s
Wi
l og 1o pg /ml : ng /IDl in parenthese s ng /lll1 in parenthese sNS = not signifi c ant : + = p<O . l : + + = p <0 . 05 :
++ + = p <O . Ol : difference between po st
t re a tment sample s adj usted by c ovar iance for varying pre trea t ment l evel s .
Sample s Sa l i cyla te Sa l i ne 1 -2 3 1 - 2 3 1-2 3-4 1-2 3 9 0. 2 8 5 . 4 2 . 6 9 01 ( 489 . 9 ) 2 . 716 0 ( 5 2 0 . 0 ) 3 . 3 88 8
( 2. 447 )
3 . 4 271 ( 2 . 6 73 ) 1 . 1470 ( 1 . 3 16 ) l . o636 ( 1 . 13 1 ) 2 . 6 198 ( 416 . 7 ) 2 . 5966 ( 39 5 . 1 ) 3 . 6 28 2 (4.
248 ) 3 - 53 7 7 ( 3. 449 )
1 . 2841 ( 1 . 649 ) 1 . 23 66 ( 1 . 5 29 ) T p c NS NS NS NS NS NS NS NS + NS NS NST = between t reatme nt s ( sa l i cyla t e versu s sal i ne )
P = between per i ods ( Tues and We d ver sus Thur s and Fr i )
133
Nei ther GH nor prola c t in levels changed in a ny signifi ca nt manner following gluc o se or VFA t re s t m�nt s ( Figure s 2 2 and 23 , Table s XXI and XXI I . The sa l i cyla te treatment influenc e d none o f t he three hormone s mea sured, nor glu cose l evel s ( Figure 24 a nd Table XXI I I ) .
Calf no . 7
28 29 30
Pla sma insul in le ve l s ( ng /ml ) in i nd ivi dual c a lves in t he fir st sample a ft er glucose and VFA t rea tment s .
Period 1 Per i od 2 Period 1 Per io d 2
0 . 61
1 . 04 0 . 3 5 0 .97
0 . 86
o.
73 3 . 26 0 . 931 . 08 3 . 39 3 . 87 5 . 29
o . 23 0 . 33 2 . 94 5 . 83
Rel a t ionship between insulin re sponsivene s s and basa l GH leve l s .
Da t a repre sent number o f c a l f sampl i ng occa sions falling into each c a tegory .
Insulin l ow responde r s = leve l s < 1 , 00 ng /ml
High ba sal GH leve l s = minimum > 4 . 00 ng /ml
Glucose t re a t me nt da ta no t i n parenthe se s VFA treat ment da ta i n parenthe se s
Insul in low r e sp onders Insulin re sponders High ba sal GH Low ba sal GH 4 1 ( 0 ) ( 3 ) 2 1 ( 2 ) (3 )
gene ra l � gre a t e r t han tha t t o gluco se . A s gluco se di d no t rea ch such high pla sma l eve ls a ft e r VFA t re a t men t e a i t di d a ft e r gluco se trea t me nt , the i n sul i n secr e t i on wa s probably o c curr i ng a s a d i rect r e s ponse t o VFA s a s
well a s t o glu co se . The finding tha t a c l o se r rel a t ionship ma7 e xi s t be tween VFA leve l s a nd insu l in s e cretion, than between g luc ose leve l s and i nsul i n secr e t i o n , i s in agre e ment with fi nding s for she ep ( Manna a n d Bo da ,
1967 :
Horino e t el ,
1968 ) .
I t see ms that in the r umina nt panc re a s , the r ol e o r gluc o se may be diffe rent from the situ a t i o n in stu die s with non-rumi na nt pancre a s , where the pre sence of gl uc o se wa s found t o be o f primary import ance a s a p o t ent i a t o r of the insulin relea se ( Ger i c h e t a l ,1974 :
Hermann a nd De ckert( 1977 ) .
The study o f Amb o e t a l( 1973 )
i s no t eworthy bec a u se the same do sage s o f glu co se and VFA s e a were use d in t he pre sent study ,were empl oyed, and the insul in and gluc ose re sul t s obt a i ne d i n sheep bore a very s t riking resemblanc e t o the o rde r of magnit u de of the r e sponse s obt a ined here ( making all owa nce for t he fac t tha t the VFA s were inj e c t e d a s an e quimo l a r mixture here ) .
The rela t ive ly strong insul i n re sponse t o VFA s is a r esponse which i s c o ns t i tu t i onal for rumina nt s , a s the c a lve s used i n thi s e xperiment ha d ha d no a c c e s s t o sol i d feed, and therefore would no t have been previou sly expo sed to rumen pr oduc t i on of VFAa. The same concl u si o n wa s reached b y Her telendy e t al ( 1969 ) , working w i th la mb s .
Although t he re sponse seeme d t o be o� physiological
signiri canc e in re l a t i on t o the ab sorption or VFA s a s the main energy substra t e s in the a dult rumi na nt , i t s role i s
not �lly unde rstood, in vi ew o � t he �a c t tha t when VFAs
were adm i ni stered int ra -rumina l ly , the i n sul i n re sponse
wa s not ob served
(
Ba s se t t , 19 7 2 ) . Moreove r , i ni t ia l insul i n se cret ion i n re sponse t o f ood intake, wa s ob served t o o c curbefore a ny inc rea se in absorption o� dige st i on produ c t s ,
end was t he re�ore thought t o b e el i c i te d by means o f neural
s timul i , ra ther than by me tebo l i t e s (Chase e t a l , 1977 ) .
The extreme va riabi l i ty o� t he insul in re sponse
( Table XXIV ) wa s a l so ob served �or insulin l ev e l s a fter
reeding i n Experiment 1 . A s in Experiment
1,
i t i s aga in of int er e st to a t tempt to c orrela te the phenomenon o� l ow responsi veness t o the po ssibl e a drenergi c sta tu s o f thecalve s . I f i t i s t o b e e xpe c t ed tha t h i gh endogeno u s leve l s
o f epine phrine e re the c a use o f low re sponsivene s s o� �
cells o f t he pancrea s , the l ow r e sponders should b e t he
calve s which showed the mo s t a dve rse reaction t o t he VFA
infusion. Compari son of VFA trea tment date or Table XX
with i nsul in re sponse s o f Table XXIV, indicate s t ha t 1� a ny
relationship exists , h oweve r , i t i s the reve r se , wi th the
low re sponsive calf be ing the one wi t h no s i de -e ffec t s .
I n Experiment l , i t wa s also observe d tha t the
insul in low responsive calve s were , in three ea s e s out of
four , the only calve s wi th GH basa l leve l s o� mo re t han
� ng /ml . Table XXV shows re sul t s o f an inve stigation i nt o
the same relat ionship her e . There i s no evidence tha t
insuli n low re sponsivene s s correlated wi th hi gh ba sa l
The lack o � re sponsivene s s o� GH to any o � the trea tment s , in e i ther di recti on, means tha t thi s
'
experiment ha s no t she d any l ight on re la t i onship s be tween ene rgy eubstrate leve l s and GH se cre t i on in young c a lve s . '!'he lack o � resp.oneivene s s i s unu sua l �or ruminant s
(
Wa llace and Ba s se t t , 1970 : Stern e t al , 1971 : Her telendyand Kipni s , 1973 ) , but there a re many e xampl e s o f' GH being unr e spons ive t o the st imul i whi ch c a u se i t s secre t i o n in man, in o ther spec ie s , e . g . c a t
(
Kokka et al , 1971 ) , rabb i t(
Mc intyre a nd Odell , 1974 ) and mou se ( Schindler e t a l ,1972 ) , and the l i t era ture i s d i sc ussed on page s
8
- 1 5 . The l a ck o � r e sponsivene s s o f' pr olac t in t o a nyof' the t rea tment s i s t o b e expe c te d i n vi ew o f' the f'ac t tha t o ther workers have not f'ound a ny r e la t i onship b e twe e n energy sub st ra te l evel s a n d pr ola c t in ( McAtee and Trenkle ,
1971 : Bryant et a l , 1970 ) .
3 . 2 . 4 Conclu sions
1 . The pre sent s t u dy i s in agreement wi th o t her
studi e s wi th ruminant s , i n tha t c i rcul a t ing VFA ( a dminist ered ,
at 1 . 25 mM /kg body we ight
)
a ppear t o s t i mula t e a n i n creasein pla sma insul in leve l s more strongly than hyperglycaemia .
2 . G H and prola c t in l evel s in pla sma were not
af'f'ected in any way by t r e a t ment wi th 1 . 25 mM /kg body weight glucose or VFA .
None o f' the three hormone s wa s influenc e d by trea tment wi th 40 mg lkg b o dy weight sa l i cyl a te , an agent
� 7
whi ch i s known t o decrea se pla sma �ree �atty a ci d leve l s . The l eek o � GH re sponsivene s s t o any o� the trea t�ent s used, wa s unexpected in view o� other st udi e s wi th ruminant s .
EXPERI MENT
Intravenou s arginine infU s i on ha s been shown t o el i c i t an increa se in pla sma GH and insu l in leve l s in a lmost all anima l s studied, and it a l so eli c i t s a pr olac t i n re sponse in sheep ( reviewe d o n page s 4 , 9 and 28) . In
the pre sent experi ment , the st imulus of an arginine
infUsion t hrough a j ugular c a theter , wa s use d to inve s t i ga te the re sponse s o f all t hree hormone s in calve s of di fferent age s and wi t h di fferent degree s of rume n development .
Experi ment al gr oups of c al ves used in
Experiment 3
Group N o . Age Die t Dige st i on
Mi lk Wea l
Ml 5 l week fe d by tea t none pr e-ruminant
M5 5 5 weeks fe d by t e a t none pre-ruminant
R5 4 5 week s fe d by bucket meal + ruminant
hay
The expe riment a l groups o f ca lve s were a s
described in Table
XXVI .
Calve s were all fema l e Jer sey-Frie sian c ro ss-bre d . The same ca lve s wer e u sed a t
di�erent age s tor group Ml and M5 , and milk wa s fe d
through a teat in orde r t o st imula te oe sophagea l groove
closure and prevent rumina t ion ( arskov ,
1972 ) .
R5 ca lve swere fed milk from a bucke t and a l so given sol i d tee d
from t he day they were obt a ined ( a t 4 - 5 day s o f age )
139
mode o'f digestion , but o therwi se the ir t rea tment ( 'e . g . housi ng e t c . ) wa s i dent i cal end ha s been de sc ribe�,
toge the r with deta i l s o'f ca theter i sa t ion and compo si t i on or meal , on page s 43 - 46 .
Experimenta l proce dure for each 'five-day t rea tment peri o d in Exper iment 3 .
Period Day Trea t ment Do sage Molari ty Volume
g /kg bw ml /kg bw
l Control No solut ions admini stered
(2
Arg inine 0 . 31.72
1 . 0
Peri o d1
( 3 NaC1
0 . 1 l .72
1 . 0
( 4 Arg inine 0. 31. 72
l . O Period2
( 5 NaCl 0. 1 l .72
1.0
Al l trea tments were admini s tered in a 30-sec ond pulse through the catheter .
The e xpe ri me nt a l de sign involved a five- day regime which wa s i de nt i ca l for all three group s o'f calve s
(Table XXVII ) . Because the
1.72
molar arginine mono hydrochloride solut i on entering the circula t ion would cause an immediate i ncrea se in pla sma o smolali ty o'f approximately18%,
t he saline tre a t ment s were give n a t the same volume and o smolal ity s s the1 . 72
M argin i ne . Solutions were ma de up t o the appropria t e volume and pH and then sterilise d by a utoclav1ng et1 . 1
kg /cm 2 'for15
ai nut e s .A s in Expe r i ment 2 , ea ch calf a c t e d a s i t s
own cont r ol wi thin e ach o f peri od l and pe r i o d
2 .
However , the pre sent e xper iment di d no t invo lve ereversal de sign end the order o f treatment days we e the
same for all calve s .
The blood sampling t echnique ha s been de scribed
on page �7. Sampling began between 8 .3 0 end 9 . 1 5 hours
each day. and wa s c ompleted by 1� . 00 . at which t ime
feeding took place . On Day 1 . ten 3 -ml blood samples
were taken at regular 30-minute interval s . On days 2 -
5 . the fir st four samples were 10 minutes apart for two
samples before and two a fter each infu sion. and a t 3 0-
minute i ntervals for samples 5 - 10.
Calve s were weighed weekly , a nd their re ctal temperature s were mea sured a pproxima tely once each hour on sampl ing days.
The growth pa ttern ot individual calve s i s
shown i n Figure �� and average growth ra tes i n Table XLVI . The growth rates were hi gher for group R . reaching the
0,3 kg body we ight ga in per day , which the ir feed ra t ions predicted ( page �6 ) . The i r s olid feed c onsumption
increa sed steadily throughout the experimental peri od (Figure �5 ) . Growth rat e s for group K were comparable with those obtained in Experiment
2.
The rectal temperature s are plotted i n Figures