Uncons trained max .
Max . LN / 3 2
2700 2 800 2900 3000 31 00
D I ETARY ENERGY ( k . ca l . M . E . per Kg . )
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energy c onc entrat ion , an increas e in methi onine c onc entra- tion at any given energy c onc entration wil l result in
increas ed methi onine intake . Predict ed methionine intake for a ration c ontaining 2 756 k. c a l . M. E . per kg . and 0 . 30 perc ent methionine is 0 . 3 58 grams p er hen per day . This
l ev e l is higher than ac tually achi eved on any rati on in LN/32 . Fisher and Morris ( 1 970 ) have demons trat ed that
for high l evels of methi onine intake , the egg respons e is non-l inear . In this s i tuati on further res earch would b e
required b efore one c ould rec ommend layer rations bas ed on the results pr e s ent ed in Tab l e 6 . 8 .
Table 6 . 8 : Es timat ed i s o l euc ine and methi onine
rat i on l evels for maximlill1 net rev enue
I'1 . E . (X1 ) I s ol euc ine
(XJ)
Methi onine(X))
Net revenue ( 6 )( k . c al/kg . ) (% (% ( $/hen) 2700 0 . 534 0 . 303 5 - 55 2756 ( 1 ) 0 . 545 0 . 31 2 5 - 51 2800 0 . 554 0 . 31 8 5 . 4-8 2900 0 . 7'?4 0 . 333 5 . 48 2976 ( '1 ) 0 . 589 0 . 3 45 5 - 52 31 00 0 . 61 4 0 . 364 5 . 66 31 97 ( 1 ) 0 . 621 0 . 3 78 5 . 83 Energy l evel s us ed in LN/3 2
In order to overc ome the prob l em o f extrapolating b eyond the experimental range o f i s o l euc ine and methionine
l evels (perc ent) , the values for (X2 , x3 ) that maximis e and minimis e est imat ed net revenue ( 6 ) within the experimental r ange , for the metabolisab l e energy l evels of LN/3 2 , were c alculat ed . Thes e values are pre s ented in Tab l e 6 . 9 and graphed in Figlire 6 . 1 . The shaded area in Figur e 6 . 1
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r epres ents the es timated net revenue range for the range o f i s o l euc ine and methionine l evels c orresponding to each energy l evel in LN/32 .
Tab l e 6 . 9 : Maximum and minimum estimat ed net
Level M. E . (X1 ) I s ol euc ine (X2 ) Methionine ( X3 ) Net Revenue ( $/hen)
max 2756 0 . 530 0.260 5 . 30 m in 2756 0.470 0 . 220 4 . 7 2 max 2976 0 . 580 0 . 30 5 . 36 m in 2976 0.540 0 . 26 4 . 92 max 31 97 0 . 540 0 . 280 4 . 84 m in 31 97 0.500 0 . 240 3 . 85
S everal features of Figure 6 . 1 are worthy o f c omment.
Maximum es timat ed ne-e r evenue for LN/32 c los ely approximate s
the unc ons trained maximum es timated net revenue over the
l ower energy dens ity l evels ( 27 56 , 2976 k . c al . M.E. per kg . )
but there is a wide discrepancy at the high energy l evel , ( 31 97 k . cal . M . E . per kg . ) . There is litt l e t o choo s e b etwe en the b es t ration o f each o f the l ower energy dens ity
l evels but maximum es t ima.t ed net r evenue for LN/3 2 dec lines rapidly as energy dens ity inc reas e s ab ove 3000 k . c al . M . E . -per kg . Als o , there i s great er variab i l ity in e s t imat ed
net revenue of the high c ompared with the l ower energy l evels within the i s o l euc ine and methionine ranges o f LN/32 .
The shape of the unc onstrained maximum es timated net r evenue curve in Figure 6 . 1 is not what one might have
.,.. 1 40 -
s eri ous res ervations ab out predic t ing net r evenue much out s ide the bounds of an experimental region .
W e c an now turn our att enti on to the eff e c t o f varia- t i on in i s o l euc ine and methi onine l eve ls , from LN/3 2 , on e s t imat ed net r evenue. We wil � initially limit thi s dis - cus s i on t o rat ions with energy d ens iti es o f 2756 amd 2976 k . c a l . M . E . per kg . Tab 1 es 6 . 1 0 and 6 . 1 1 have b e en
c ons truc t ed from Tab les 6 . 1 and 6 . 6 .
Tab l e 6 . 1 0 : Es t imated net r evenues f or rat ions of k . cal.
Methi onine l eve l
(% ) Range 0 . 22 0.24 0.26 0 . 47 0 . 79 4 . 95 5 . 1 1 0 . 3 2 I s ol e uc ine 0 . 50 4 . 81 5.00 5 . 1 6 0 . 3 5 l ev e l (%) 0 . 53 4.84 5.07 5-23 0 . 39 Range 0 . 05 0 . 1 2 0 . 1 2
Tab l e 6 . 1 1 : Es t::.ma G-ed net revenue for rat ions o f k . cal.
Methi onine l evel
(%) Range 0 . 26 0 . 28 0 . 30 0 . 54 5 . 04 5 - 21 5 - 37 0 . 33 I s ol eucin e 0 . 57 5 - 05 5 . 21 5 . 38 0 . 33 l ev e l (%) 0 . 60 4 . 92 5 . 09 5 . 26 0 . 34 Range 0 . 1 2 0 . 1 2 0 . 1 1
From Tables 6 . 1 0 and 6 . 1 1 it would appear that changes in dietary methionine level have a greater effec t on n e t
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however , this r esult shoul d b e treated with some c auti on . I s o l euc ine intake was no t found to b e a s ignific ant vari abl e in the egg numb er produc tion func tion whereas
methionine intake was found to be s ignificant . This
result c ould w e l l have t e en due to d e fic i encies in the design of experim ent LN/3 2 s inc e is o l euc ine and methionine
l evels were not s ub j ec t to control. We can put forward
the t entative hypothes i s that ne t r evenue is more s ens i t ive to methionine l ev e l than i s o l euc ine l evel but this hypothes is should be t es t ed by further res earch.
The es t imat ed func ti ons c an a l s o b e us ed to investi gate the relati onship b etwe en net inc ome and dai ly intak e
l evels of s el ec t e d nutri ents . For examp l e , we may b e inter e s t ed in the es timat ed relati onship b etween average dai ly methionine intnke for rati ons c ontaining 0.55 p erc ent
i s o l euc ine and various energy dens ity levels. Sinc e we
have e s timat ed f e ed c onsumption for rati ons of different energy dens i t i e s (Tab l e 6 . 3 ) , we c an eas ily c al c ul a t e c or r esponding methionine dai l y intake l evels (gms per hen per day) and methionine rati on l evels (p erc ent). Thes e figur e s are pres ent ed i n Table 6 . 1 2 for s e l e c t ed methionine intake values .
Sub s t ituting for x2 = 0 . 55 (i s o l euc ine) , equa t i on 6 . 1 1 b e c omes :
This e quat i on c an then b e us ed to r e l ate es timat ed net revenue and energy dens ity of different average dail y methionine intake l evel s for the t otal period of lay .
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Thes e r e l ati onships are pr es ent ed in Figure 6 . 2 . We c an note , that i f our estimat ed func t i ons were as sumed to hold true for a dai ly methi onine intake of 0 . 35 grams/b ird/day , there would b e l ittle to choos e , in t erms of net r evenue , b etwe en rati ons of differ ent energy dens ities , formul at ed
to meet this methionine intake . Ho�ever , we c an a l s o note that this c onc lus i on involves an extrapolation b eyond the l imits of LN/3 2 for the 2756 and 31 97 k . c a l . M . E . p er kg r ations .
T ab l e 6 . 1 2 : Methionine rat i on l evels ( %) to differen t methi onine intake l evels
M ethi onine intake (gms/hen/day) . 25 • 27 • 29 • 31 . 33 - 35 6 . 8 C onc l us i on M . E . ( Feed 27 56 ( 1 1 9 . 34) 0 . 2095 0 . 2262 0 . 2430 0 . 2598 0 . 2765 0 . 2933 ( k . c al/kg rat i on) int ak e , gms/hen/day) 2976 31 97 ( 1 1 5 . 80 ) ( 1 1 2 . 24 ) ( X3 ) 0 . 21 59 0 . 2227 0 . 2332 0 . 2406 0 . 2504 0 . 2584 0 . 2677 0 . 2762 0 . 2850 0 . 2940 0 . 3022 0 . 31 1 8
The e c onomic analys i s pres ent ed in thi s Chapt er s ugges ts that , for the nutri ent dens ities us ed in LN/3 2 , a rat i on formulat ed to c ontain : 2976 k . c al . M . E . per kg ,
0 . 30 p erc ent me thionine and 0 . 58 p erc ent i s o l euc ine
(Tab l e 6 . 9 ) wil l maximis e net r evenue under the given pric e s truc tur e .
Q) ;::l I:: Q) > Q) � +-l Q) z 6 . 0 5 . 5 5 . 0 4 . 5 4 . 0 3 . 5 1 43 - Figur e 6 . 2
RELAT IONSHI P BETWEEN ESTH1A��E l' N ET R E V ENUE AND ENEEGY DENS I TY AT D I FFE l�ENT DA I LY M ET l ! I ON I N E
I N TAKES ( GMS ) ; I S OLEUCI N E A T 0 . 5 5 PERCENT .
- - - - - - - - - .. .. .. ... . - -- 0 . 3 5 .... ... ... ... ... 2 700 .. _ - - - - - ... - - - - - - - - - - - - - - - ... ... ... .. ... _ - ... ... .. .... ... ... .... ... ... ... - - - - - ... _ ... ... .... ... .... ... ... ... ... ... ... .... ... 2 8 00 2 9 00 - - - ... 0 . 3 3 - - - ... _ _ ... ... - - ... .. o . 2 9 - ... - - ... .... .... .. 0 .27 .... ... ... ... - .... ... 0 . 2 5 3 0 0 0 3 1 00
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We should s tress that thes e results are depend ent on the l evels of the exogenous variab l es , espec ially pro - duc t (e ggs and culled hen) and fe eds tuff pric es . The
analys i s pr es ent ed applies t o pric es current in Dec emb er ,
1 973 . Should the pric e o f high energy f e eds tuffs (maiz e ,
wheat) decrea� r· in relat i on to the pric e o f low energy
f e eds tuffs (pol lard , barl ey) then high energy dens ity
rations c ould r esult in maximum net revenue .
The ec onomic analys is of values for the c ontrol
variab l e s , methi onine l evel and i s o l euc ine level in the ration , that fal l out s ide the range of thos e us ed in LN/32 should b e treat ed with a great deal of c aut ion. At b es t this analys is c an b e us ed t o e s t imat e the pot ent ial b enefit from further r e s earch us ing levels outside the range of
thos e us ed in LN/3 2 ; but even her e it is likely that rati on
c os t or rat ion infeas ibi lity should be investigat ed further
b efore ac tual experimentat i on is c ont emplated (Towns l ey ,
1 971 ) .
The ec onomic analys is has b een limited t o th e c a s e
where given rati ons are f e d ad lib itum during the ent ir e peri od o f lay . LN/32 was not des igned t o inves tigat e the
e c onomi c s of phas e feeding though s ome att ent i on is given t o this t o pic in Chapt er S even . Als o , LN/32 was not designed
spec ifically to estima t e produc t i on respons es to differ ent i s o l euc ine and methionine l evels and future r es earch r esults from P . R . C . should enabl e the est imation of thes e r e l at i on- ships with greater c onfidenc e . The primary aim o f thi s Chapt er has b e en to illus trat e one appro ach t o the e conomic
•'
.. ' I •
- 1 45 -
analys is o f layer rati ons inc orporat ing respons e func t i ons for the endogenous variab l es o f the produc tion s ys t em
- '1 46 -
CHAPTER SEVEN
ASPECTS OF LAYER RESPONSES
7 . 1 Introduc ti on
LN/3 2 was originally des i gned t o ob tain quantitative
•
e s t imat es o f layer respons es that we�e of economic s i gnifi c anc e . This analys is _was the b as is o f Chapt er Five. LN/3 2
however provided information o n other as pects of layer r espons es .
Inc luded ln LN/32 was t r eatment '1 7 t o s tudy the
e ffects of prot ein s ourc e on layer respons es. Tre atments '1 6 and '1 8 were des i gned to study the e ffects of r e s tric t ed
f e eding on layer respons es.
Although LN/32 was not des igned to study aspects of
phas e fe eding of layers we c an analys e the r esul t s for
p eriods within the laying cyc l e in an endeavour to det ermine i f respons e s are affected by di fferent nutri ents at dif- f erenc e peri ods in the laying cyc l e . We can cho os e two p eriods ( '1 -'1 40 , '1 68-3'1 5 days) for this analys is as they
c orrespond with changes in rati on c ompos it ion for treatments '1 , 3-6 . :: t mus t b e stres s ed that this analys is d o e s not t ake ac c ount of changes in the rat i on as is inferred by phas e feeding.
In this Chapt er we wi l l analys e the following asp ec ts o f LN/3 2 :
( 1) Treatment 1 7 .
( 2 ) Treatments '1 6 , '1 8 .
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7 . 2 Treatment
Rati on 1 7 was formulat ed to the s ame energy and prot ein d ens ity as rat ion 1 4 ( 31 97 k . cal . M . E . per kg . , 1 7 grams prot ein intak e bas ed on an intake of 305 k . c al.
M . E . p er day) . In addit ion , ingredi ent c ons traints were
imposed.
1 . A minimum inc lus i on rat e o f 1 . 5 perc ent butt ermilk powder.
2 . A minimum inc lus i on rat e of 1 0.0 perc ent
pollard .
This ration was formulated to inc lude prot ein s ourc e s o f proven qual ity. I t had b e en suspec t ed that the high
meatmeal inc lus ion rate in rat ions of 31 97 k. cal. M.E. per
k g. would reduc e the range o f prot ein s ourc es to virtually
meatmeal alone. Should the n1eatmeal have an imbalanc e of amino ac ids then i t was suspec t ed there may have b e en a r educ ed egg output. To t es t for any r espons e t o the
ingredi ent inc lus ion we c an c ompar e treatments 1 7 and 1 4 .
7 . 2 . 1 Feed intake
Treatment 1 7 ( like treatment 1 4) was fed ad lib i tum.
F eed intake for treatments 1 4 and 1 7 for the 31 5 days of the laying cyc l e are pres ented in Tab l e 7 . 1 •
. .
Apart from White Bas e ( a ) l ayers the £.eed ' intake is s imilar for both treatm ents. An examination of the f e e d intake o f Whit e Bas e ( a) layers for a l l treatments shows that intake for this strain was greater on treatment 1 4 than on treatments of a s imil ar energy c onc entrati on ( 31 97 k . c al . M . E. per kg . ) .
? . 2 . 2
- 1 48 -
Tab l e 7 . 1 : . H . D . feed intake . Treatments
· � Treatment 1 4 1 7 w . B . ( a ) 1 1 6 . 1 1 0'1 • 2 nw:nb er Strain 1-l . B . ( b ) '1 '1 6 . '1 '1 '1 5 . 7 l"' . L . '1 '1 3 . 4 '1 '1 '1 . 3 Total 345 . 6 328 . 2
Egg numb er for tr eatments '1 4 , 1 7 for the t o tal laying peri od are pre s ent ed in Table 7 . 2 .
Tab l e 7 . 2 : H . D . numb er . Treatments
Treatment W.B. (a) Strain W . B . ( b ) M Total
.L.
'1 4 2'1 6 . 6 207.4 2'1 6 . 9 640.9
1 7 200.0 206.3 214.7 62'1 . 0
Again , Whit e Bas e ( a) layers are the only s train
wher e there ar e respons e diff erenc es . There is a posi tive
c orrelation b etwe en f e e d intake ( and henc e nutri ent intakes )
and egg numb er for all s trains o f layers. Although 1-lhit e
Bas e ( a ) layers on treatment 1 7 did not p erform t o the l evel o f that s train on treatment '14 they did p erform b e tt er than l ayers on treatment '1 3 and '1 5 ( al s o 3'1 97 k . cal . M . E . p er kg . ) . We can only hypothes i s e that 1-lhit e Bas e ( a ) lay ers
on treatm ent '1 4 responded to an increas e in feed intake
which resul t e d in an increas ed energy intake . We c annot
explain why this differenc e in f eed intake occurr ed .
In general , we c an say that there was no diff erenc e
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c onsumed in exc ess of 1 7 grams o f protein ( treatment 1 4 =
20 . 53 grams , treatment 1 7 = 1 9 . 51 grams ) the hypothesis
that pro t ein quality may b e suspect c ould not b e t es t ed in
the light of overc onsumption of prot ein .
7 . 3 Treatments 1 8
I t was suspected that hens fed a die t of 31 97 k . cal . M . E . per kg. may c onsume in exc ess of 305 k . c al . M . E. p er
day . Should thi s occur , i t was decided to r e s tric t the
energy intake of l ayers t o 305 k. c al . M . E . per day to det er-
mine what effect res tric t ed nutrient intake would have on
l ayer produc tion. Two treatments (1 6 , 1 8 ) were as s ign ed t o
a restric t ed feeding regime.
\
Treatments 1 6 and 1 8 were formulat ed t o the s am e
energy and prot e in dens ity as ration 1 4 ( 31 9� k. c a l. M . E .
per kg . ; 1 7 grams protein intake bas ed on an intake o f
305 k . c al . M . E . per day) . In addition the ingredi ent