1319

Effects of Early Feed Restriction on the Occurrence of Compensatory GroMh,Feed Conversion Efficiency, Leg Abnormality and Mortality in Unsexed Broiler

Chickens Reared in Cages

U. Santoso+

Department ofAnimal Science, Faculty ofAgriculture, Bengkulu University

Jl. Raya Kandang Limun, Bengkulu 38371 A, Indonesia

ABSTRACT : Two experimelts were conducted to evaluate the effect of early feed restriction on grouth, fe€d oonve$ion ratio(FCR) and mortality in unsexed broiler chickens. In Expe ment 1,350 one-day-old bmiler chickens were divided into 7 goups. Eachteatmert group was represented by five replicates of ten brcilers each. One $oup was fed ad /iDr'rr|r, as the control $oup and the othersix groups were fed 25o/o ad libiturn (25% multiplied by aoount of feed intake of ad libitun chick&is at the previous day) for 4 or 6d^y\ sv/o ad libitun fot 4 or 6 days, ard 75olo ad libilum fot 4 ot 6 dzys. In experiment 2, 500 broiler chickens rere divided into l0g.oups. Each treatment group was represented by five replicates of ten broilers each. One go\p was fed ad libitun as the coftrol group.Three ages offeed restriction ititiol timing (2, 4 or 6 days ofage) and lhree types of feed restriction (physical restriction, meal feeding

and diet dilution) were used (3x3) in both exp€rimeots. Th€y werc feed-testricted for 6 day$ Results showed that restricted broileNexhibited comp€nsatory growtb in both experimerts exaept for diet dilution groups, ln both experiments" FCR ofBstricted broileN was

higher, whereas feed intake ofthem was lower during restriction period. FCR ofreshicred broilers was lower upoo refeeding. Mortalitywas inconsistently afected by early feed restrictio!. Leg abmrmality was lower in restdcted bmilers in both experimcnts. L€vel offeedrestriction sigoificanlly iofluenced body weigh! FCR and feed iotake ofrestricted broilers (p<0.05), but duration of feed res,l ction hadno effect Type ofrestiction significartly affected body weight, feed intake and FCR (p<0.05). It appeared dlat to achieve the best result(c.mplete compensalory gowth and beuel FCR), brcilers should he restricted at 25o/o ad libitum for 6 days (Experiment l). Mealfeeding started at 2 days of age would show the best perfo.mance (Exp€.iment 2). (Asian-Aust J. Anim ScL Xn2. yol 15, Na 9:1319-1i2s)

Key Words : Early Feed Restdatioq Compensatory Grcwtb Leg Abnormalig, Mortality

INTRODUCTION

Compensalory grovith can occur after broiler chickensare feed-restrict€d at an early age (Santoso,200lb; Santoso

et al., 1993b, I 995ab). Body weighG of restricted chickens

can exceed those of ad libituu chickens (Plavnik and

Hurwitz, 1990; Santoso, 2001q Santoso et at., 1993b).

However, most studies of early feed restsiction used sexed

chickens. Because female and male chickens have diffsrontresponses to early feed restdction (Plavnik and Hurwitz,1988; Santoso et al., 1993ab), it is of irterest to k owwhe$er this program could be applied in uniexed chickens.Santoso (2001a) showed that unsexed chickens reared on-

floor showed compensatory growh when they werercstricted-refed at an early ages and this phenomenon wasaffected by the duration and severity of feed restriction.

It was knovm that poultry reared on-floor had differentresponses to nutritional planes as compared to those reared

in cages (Andenon and Adams, 1994), leading to theassumption that the different r€aring types may result indifferent rcsponses to early feed restriction. In addition, thesuccess of a restriction in separated sexes was affected by

i Corresponding Author : U. Santoso. Tel: +62-736-21170, Fax:+62-73G28616-Received February 20, 2002; Accepted Jun€ 3, 2002

initial ages at which broilers wer€ resficted (Ballay et al.,1992; Plavnik and Hurwitz, 1988; Su et al., 1999), and

types of feed restriction (Su et al., 1999). Ho\yever, no

study has been conducted to eyaluate these factors inunsexed chickens. Therefore, two studies have b€en

conducted to evaluate the response of broiler chickensreared in cages to early feed restriction, and to deteminethe offects of duration and severity of fesd restriction, initialage and type of feed restriction on the perFormance ofunsexed broilers.

MATERIALS AltlD METHODS

Experiment IThree hundred and fifty l-day-old broiler chickens

(Arbor Acres strain, unsexed, ratio of mal€s to females l: I )obtained from a commercial hatchery were used in thisstudy. Frcm I to 14 days of age, supplemental heat wasprovided with a hanging heat lamp. Temperature was

maintained at 32.5"C in the fiIst week and graduallydecreased to room lemperatue at the second week. Thebroiler chickens were maintained in the cages in a house

under continuous fluorescent lighting with feed and wateravailable ad libitum during the early dry season. At 7 days

of age, broiter chickens were divided into 7 groups. Each

1320 U. SANTOSO

heatment gmup was represented by five replicates of tenbroilen each. One group was fed ad libitum as the controlgroup and otlrer six groups were fed 25o/o ad libitun (25o/o

multiplied by amount of feod intake of ad fibiluz chickensat the previous day) for 4 or 6 days, 50% ad libitum for 4 or6 days, a]nd 75o/o ad libitum for 4 or 6 days. Thereafter, theywere fd ad libinm to 56 days of age. Water was provided

ad libitum and recommended husbandry practices were

fotlowed in this experiment. Broilers were fed a commercialstader diet from 1 to 28 days of age, and a commercialfirisher diet Aom 29 to 56 days of age. The nuaientcomposition ofthe commercial feed is published elsewhere(Santoso, 2001a). Broilers were weighed individually on aweekly basis except during feed restriction period, and feed

intake was recorded daily. Recovery index during refeedingperiod was caloulated using the following equation: (A-ByAxl0o%, where A was the difference of body weightbetween control group and restricted broilers at th€ end offeed restdction and B was the difference of body weightbetween coDtrol goup ard rcstsicted bmilers at 56 days ofage (Brody, 1964). Mortality was also determined.Individual broilers were assigned leg scores of I (no visibledisorders); 2 (mild), given to broilers able to walk but witha light limp; 3 (moderate), given to broilers with a moredistinct limp; or 4 (sever€) given to broilers who have great

difiiculty in walking and would likely be culled undercommercial practice Q{ester et al., 190).

All data were statistically analyzed using analysis ofvariance. Significant difference between featments wasdetermined by single d.f. orthogonal contrasts. Factorial

design (2x3) was used to evaluate the effect ofduration and

level of feed restriction and its interaction- Significantdifference was determined by Duncan's Multiple Range

Test (Duncan, 1955).

Experiment 2Five hundred l-day-old broiter chickens (Arbor Acres

strain, unsexed, ratio of males and females=l:l) obtained

from a commercial hatchery were used in this study- From Ito 14 days of age, supplemental heat was provided with a

hanging heat lamp. Temperature was maintained at 32.5'Cin the first week and gradually decreased to roomtemperatue at the second week. The broiler chickens weremaintained in the cages in a house under continuousfluorescent lighting with fecd and water avail able ad libitumduring the early dry searcn. At 7 days of age, broilerchickens were divided into l0 groups. Each trearment group

was represented by five replioates of ten broilers each. Onegroup was fed ad /rDr'l m as the control group. Three ages offeed restriction initial timing (2, 4 or 6 days of age) and

three types of feed restriction (physical restriction, meal

feeding and diet dilution) were examined in a 3x3 factorial.Physical restriction was conducted by feeding broilerchickens at 25o/o ad libitum (the best result in Experiment1); meal feeding was conducted by feeding broiler chickensfor 6 h &om 08:00 to 14:00; diet dilution was conduoted byfeeding broiler chickens with a diet diluted with sawdust

Q5:75). mey were feed restricted for 6 days. Thereafter,

they wero fed ad libitun to 56 days of age. Water wasprovided ad libitun and recommended husbandry practices

and variables measur€d were similar to Experiment 1.

All data were statistically analyzed as in Expsriment L

RESULTS

Experiment ITable 1 shows the effects of early feed restriction on

body weight gain, feed intake and feed conversion mtio

@CR) during feed restriction. Body weight gain and feedinta&e of restricted broilers were significantly lower as

compared to the contrcl (p<.01) at the end of the

restriction period. FCR was significantly higher in bmilersfed 25o/o ad libitum f$ 4 (p<0.001) or 6 days (p<0.01),

50 % (p<0.05) and 75o/o $<0.05) od libftam for 4 days. Nomortality was observed during this period.

Table 2 shows the effects of eady feed restriction on

Trblc 1. Eff€ct ofea y feed restrictiotr on gIowlb, feed intake and feed coaversion ratio during feed restrictionr @xperiment l)

Variables4 d of rcstriction 6 d of iestriction

250/o 500/" 250/o Str/o 75"/"SD

Body weight, g/chick7d.ltd13d

Feed intake, g/chick7-tt d

7-13 dFeed conversion mtio

7-l I d

7-13 d

t09 loEI l0*. 137..

291,t 58 **

29.3*** 2.0,

ll3220

305

136

263

1.25

t.37

109

I58.r

88 ',

1.79*

134r,*

2.29ar

108

l89r'*

r l5**

t.41

?34'r

t7t*

1.39

3.744.4

61.3

13.3

24.3

1.10

0.45

109 tll

rValues rcported rcprcsent me3ns for 5 pens of 10 broilers each.., .* or *++ Significantly different ftom the control goup at level p<0.05; p<0.01 or p<0.001, respectively.

EARLY FEED RESTRICTION AND COMPENSATORY GROWTTI IN BROILERS

Table 2. Effect ofea y feed restriction on groEth, fe€d intake and feed conversion ratio during r€feedingl (ExDeriment l )

1321

4 d of reshiction 6 d of reskictionVariables SD

BWG, g/chickr 2-s6 d

14-56 d

Feed intake, g/chickt2-56 d14-56 d

Feed conversiont2-56 dl,t-56 d

2,t142,031

4,5644,438

2.t62.19

2,230 2,2ttr

4,619

2.09*

4,803r

2.15

4,515

2.054

2,20t.

4,403

2.00.

2,070

4,432

2.14

72

2,142* 123

t524,636 178

0.062.16 0_05

'Values reported r€present means for 5 p€ns of l0 bmilers each-* Significandy differcnt from the conEol group at lovel p<0.05 or p<.01 respectively.

body weight gain, feed intake and FCR during refeeding.Body weight gain was significantly highq in broilers

fed 50-75o/o ad libitum for 4 days fu<0.05) an d 25o/o or 7 5o/o

(p<0.05) ad libitum for 6 days (p<0.05). Feed intake washigher in restricted chickens fed 75o/o ad libitum for 4 days(p<0.05). FCR was significantly lower in broilers fed25-50o/o ad libinn for 4 days, and 25o/o ad libitum for 6days (p<0.05).

Table 3 shows the effects of emly feed restriction onbody weight, feed intake, FCR" mortality, leg abnormalitiesand recovery index at 56 days of age. Body weight was notsignificantty different, v/hereas feed intake of chickens fed25-50Vo ad libitun for 6 days was lower compared to theconfol (p<0.05). Feed conversion ratio of chickens fed25o/o ad. libilum for 6 days was significantly lower as

compared wilh the control (p<0.05). Completecompensatory growth was observed in restricted chickens

as indicated by recovery index > l00o/o except for chickensled 50o/o qd libitun (p<0.01). Mortality was lower inchickens fed 25, 50olo or 75o/o ad libitum for 4 days and 25%ad lhium for 6 clays as compaxed to the control. L€gabnormalities of restricted broilers werc significantly lower(p<0.05) as compar€d to the confol except for broilers fed75o/o ad libitum for 6 days.

Body weightFeed intakeFCR

Recovery index2

Mortality, %

FCR (p<0.05) and feed intake (p<0.01) of chickens at56 days of age. Recovery index of restricted chickens wassignificantly affected by duration (p4.0i) and level of feedrestriction G)<0.01).

Experiment 2Thble 5 shows the effects of early feed rgskiction on

body weight, feed intake and FCR during feed restriction.Body weight and feed intake of restricted broilers weresignificantty lower compared to the control (p<0.001) at theend of restriction period. FCR was significantly higher inrestricted broiler (p<0.01).

Table 6 shows the effects of early feed restriction onbody weight gain, feed intake and FCR during refeeding.Body weight gain was significantly higher in broilerssubjected to physical restriction started at 2 or 4 days ofage,meal feeding started at 2 days of age (p<0.05). Feed intakewas significantly high€r in meal feeding started at 2 days ofage (p<0.05), but it was significantly lower in diet dilutionstarted at 2,4 ot 6 days of age (p<0.05). FCR wassignificantly lower in broilers subjected to physicalrestriction started at 2 or 4 days of age, meal feeding startsdat 4 or 6 days of age, and diet dilution started at 6 days ofage.

2,393 2,3364,891 4,460

Table 4 shows the effects of duration and level of feed Table 7 shows the effects of early feed restriction on

rcstriction on body weigit, feed intake an! FCR. Jt was body weight, body weight gain, feed intake and FCR,

shown that the level offeed restriction affeoted body weight, recovery index, mortality and leg abnormalities at 56 days

Table 3. EITect of early feed rest iction otr body weight, feed iota&e and feed conversion €tio, r€covery index, mortality and legabnormalities in boiler chickens at 56 days ofager (Experiment l)

Variables aon*, 4 days ofrestriction 6 days ofrestriction250/o 500/o 750/o

'5%

-'- sn

2,336 2,3404,710 4,604

2.12 2.06- l04b64

2,3484,617

2.09

I l4h2

2.14

lg2d4

100 b

2

2,259 2,3764,547' 4,807

95

t502.00* z.tt 2.11 0-04

34" 156" 2066

Leg abnormality 1.3 1.08* 1.04' 1.04,1 1.02* 1.061 1.24 0.03' Values reported repr€sent means for 5 pens of l0 broilers each.. Signific.€ndy different from the mntrol group at level p<0-05; p{.01 or p<.001, respectively.1 Means within a row not follow€d by the sarne superscripts are significantly different.

1322 U. SANTOSO

Table 4. Effecr of dumtion and level offeed restriction on body weighq feed intake and fged cooversion ratio in broiler chickens at 56.lqv<

^f qo.l rF'lrFi-".! l'l

VariablesDuration of r€slriction Level of rcstriction ANOVA

4d 6 d 250/0 500/0 150h

Body weight 2,360 2,332 2,318' 2,303' 2,411b 96 <0.05 NS NSFeed intakeFCR

4,111 4,6r r 4,54r" 4,602', 4,849b A5 <O.OI NS NS2-07 2.02' 2.10b 2.13b 0-06 <0-05 NS NS2.t0

Recovery index l37B g7^ l02b 74' 114' 2l <0.01 <0.01 <0.05

L=trvel of resEiction, FDumtion of restrictioir, LxD=Interaction.Means within a rc\, not followed by the sam€ supeNcripts are significandy different.

Table 5. Effect ofeariy feed restiction oa body weight, feed irtake and FCR during feed rest ictionr (Experiment 2)

VariablesPhysical fe€d restriction Meal feeding

2d 4d 6d 2d 4d 6dDiet dilution

4d. 6d2dBWG, g/chick

2-8+106-12

Feed intake, g/chiok2-84- l06-12

FCR2-84- l0G12

128 l5**rt50199

174 36r.*r.286358

1.36 2.36**1.90l.8t

2.13.2.40r

4.5

14.5

212*** 20.6

20.0t5.4

64*** 21.5

0.08

0.0723e". 0.3

2g**+

82*,r*

55***

g4*rt

32*t*6l:i** 15ur,r, *

82***

36*t*t29** 46'.'.*

197**

I l-542*r,*3.092**+

1.53

r.84

' Values reported represent means for 5 pens of l0 broileB each.? The significance ofthe negative lalues.*, ** or t+* Significantly different from the contol gmup at level p<0.05; p<0.01 or p<0.001, respectively

Trble 6. EITect oi feed rcstriction on

Variables Control

feed intake and FCR

Physical feed restriction Meal

2d 4d 6d 6d2dBWG, g/chick

8-56l0-56t2-56

Feed intake, g

8-56l0-56t2-56

FCR8-56

l0-56t2-56

2,364*2,t902,1352,048

5,t125,0354,902

2,1042,187 2,084

2,169

s,073

2.02*

4,a21* 120

4,785t I 15

4,781 4,5561 122

2-29 0.06

2.29 0.072.20* 2.t4* 0.05

75

9l2,130 92

2.36

2.36

2.39

484r

2.13'

5048

2.20*

2,1 t5

4794

5,327*

) rt

2.27V6lues repo(ed represent means for 5 pens of l0 hroilers ea.h

t Si8nifica.ntly different from the control goup at level p4.05.

of age. Body weight of broilers subjected to physicalrestriction and meal feeding werE not significantly different,whereas in those subjected to diet dilution it wassignificantly lower (p<0.05). Feed intake was significarfilylower in broilers subjected to physical restriction, mealfeeding and diet dilution (p<0.01). FCR was significantlylower in broilers subjected to physical restriction, meal

feeding, and diet dilution sta ed at 6 days ofage (p<0.05).

Recovery index was significantly differeat (p<0,01) amongthe resticted broilers. Complete compensatory growth as

indicated by recovery index )100% occurred with physical

feed restriction started at 4 days of age, and meal feedingstarted at 2, 4 or 6 days of age. Dict dilutior startcd at 2 or 4days of age showed negative recovery index. Mortality ofrestricted brcilers was similar to the control group. Legabnormalities of restricted broilers were significantly lower

EARLY FEED RESTRICTION AND COMPENSATORY GROWTH IN BROILERS 1323

Trble 7. Effect of early feed restrictioo on body weight, feed intake and FCR, recovery index and mortality at 56 days of ager/f reriment )\

VariablesPhysical feed restriction Meal feediflg

2d 4d 6d2d 4d 6dDiet dilution

6d4d2dBody weightBWG g/chick

2-564.566"56

Feed intake, g

2-564_56

6-56FCR

2-564-566-56

Recovery index2

Mortality (o/o)

2,2872,326

2,143

4,907**5099*'

4,810**

/h

2,070* 892,087* 9t

137

4,859''s tt24,724*' 189

2,380 2,349 2,420 2277 2,482 2,381 2344 2,163* 2,t64* 2.224* 120

2,3182,2852,246

5,3935,4035,460

2.332.372.43

4

2,418* 2,100*2,28't

, r< r

5t76* 4,834**5l t6**

4,974*

2.1542.19*

72.6d 133.9f44

2-24*39.8"

41.10*

2.14*

24t.584

l.ll*

2.24*

101.1"4

1.12,

2.21*103e

4t.2t

2.30

-65.4h

4l.lt+

2.35

-30.7"4

1.14*

2.26'29.1"

41-t t.

0.070.05

0.06

25.5

0.041.21 1.08. l -091.

reported rcpresent means for 5 pens of | 0 bmilers each.* or * i Significantly ditrerent liom th€ control group at l€vel p<0.05 or p<0.01 , respectively.I Means within a row not followed by tl€ same superscripts aft significantly diferent.

as compared to the control group (p<0.05) except forbroilers subjected to meal feeding started at 6 days ofage.

Table 8 shows the effects of initial age and tlpe ofrestriction on body weight gain, body weight, feed intake

and FCR. Initial age did not affect body weight gain, bodyweight, and FCR. Restricling broilers started at 6 days ofage had lower feed intake than those started at 4 days ofage(p<0.05). Type of restriction significantly affected bodyweight gain, body weight, feed intake and FCR (p<0.01).

There was intemction b€tween initial age and type ofrestriction on feed intake and recovery index (p<0.05).

DISCUSSION

The amount of feed allocated to the restricted chickensduring the restriction period was at least sufiicient toprovide for basic maintenance and body functions (except

for diet dilution group) as these broilers gained body weightduring the restriction period. Feed intake was lower duringfeed restriction. There was a significant positive correlation

between duration and feed intake (r:0.57; p<0.05), and

between level of feed restriction and feed intake (0.82;p<0.01). It seemed that longer duration and more severefeed restriction would significantly reduce feed intake(Experiment 1).

Less severe fesd restriction might be less stressful tobroilers so thal broilers adapted more quickly to feedrestriction. This might explain better FCR during feed

restriction in less severe groups. Longer duation rcsulted irgreater body weight gain (e/day) with better FCR- It is

possible that longer duration of feed restdction allowsbroilers to ad.apt to feed restriction as far as teDperature is

maintained at an accurate level. Average daily temperature

was 29.13'C. This temperature is far fiom suitable for birdsin subtropics but it might be a proper temperature in tropicmnes. Types of restriction (Experiment 2) also influencedgro*th, feed intake and FCR. Diet dilution r€sulted innegative growths indicating that diet dilution applied was

too severe to m€et the nutrient requirement for maintenance.

The inclusion of sawdust may affect the ME cortent of the

Trble 8. Effect of initial age and type of restrictioo on body weight gai4 body weight, feed intake, FCR and recovery index at 56 days

ofage! (Experiment 2)

VariahleInitial age Type of .estriction ANOVA

SD4 6 Physical Meal Dilution IA TR IA,.TR

BWGFeed intakeFCR

2,331 2,308 2,295 2349b 2,402b 2184' 125 NS <0.05 NS4,972^8 s,o2sB 4,836A 4,939t' 5,089b 4,806" l4o <0.05 <0.05 <0.05

2.t9 2.26 2-24 2-ty 2)q 230h 0.07 NS <0.05 NS84.68 68.1A 51.5^ 82.tb 148.i" -20.5' 10.6 <0.05 <0.01 <0.05index, 7o

Values rcported tepresent m€ans for 5 pens of 10 broilers each.

IA-Initial agc, TR:Type of rertriction, IArTR=Inooraction.Means within a row not followed by the same superscripts are significantly diff€rent.

1321 U. SANTOSO

feed, having a depressive effect on energ/ balance.Initi&l age mighl be also correlated to body weight gain

(r-O.69), feed intake (r=0.51), FCR (r-0.38) during feedrestriction. Older initial age would result in better gowthand FCR with higher feed intake. Nitsan et al. (1991) foundthat at 5-10 days of age, relative growth reached its peak

and relative weight ofthe pancreas and small intestine werealso maximal in broiler chickens. At this age, broilers mightbe more adaptable to nutritional planes compared toyounger ag€s. This might be true for diet dilution, because

the prcsent study showed earlier initial age (less than 5 days

of age) should be applied for physical r€striction and mealfeeding in order to achieve optimal results.

Feed restriction has been shown to .educe the metabolicenergy loss (Mitchell, 1962), leading to reducedrequirement for maint€nance and thus improved FCRduring feed restriction. The present study, however, showedthat feed restriction increased FCR. The increment of FCRmight partly be explained by higher r€quirement formaintenance due to smaller body weight during feedr€striction.

The present study confirmed previous results (Santoso,

2001a), which show€d that unsexed restricted-broilersshoyyed compensatory groMh when they were refed.However, the present study showed that early feedrestriction did not rssult in heavier body weight as shown inthe prcvious study (Santoso, 2001a). This difference mightbe due to the different types of rearing. In the previous

study broilers were raised on-floor, whereas in the present

study they were raised in cages. It was shown that broilersraised on-floor had higher body weights than those raised incages (Andercon and Adams, 1994; Sinurar et al., 1995).

Finally, animals raised on the floor are losing less energythan the caged animals because thermal insulationmnditions are better than in cages. This factor mightinfluence the response ofbroilers to early feed restriction.

The present study showed that ioitial age of feedrestriction had no effect on tJle occurrence of compensalorygrowth. Plavnik and Hurwitz (l9EE) also found that variousinitial ages had no effect on the ocourrence ofcompensatorygrowtl in mate birds. How6ver, in females, restriction at th€earlier age of 7 days minimized the loss of body weightobserved when restriction was applied at 9 or 11 days.

Ballay et al. (1992) also found thar initial age ftom I to t2days of age resulted in compensatory growth withcomparable FCR in males. Plavnik aad Hurwitz (1988)suggested thal with mixed populations, the earlierrestriction, starting at the age of 5 to 7 days, shoutd bepreferr€d over later age. The present study showed thatinitial age of 2 to 6 days could be applied to mixedpopulations.

compensatory growth than the other tjrpes. Su et al. (1999)found that meal feeding allows broilers to compensate withbetter growth and FCR than with physical feed restriction.Furthermore, it was found thar more tequent meal feedingmight bring about better compensatory growth. This resultindicates that in ord€r to exhibit compe satory growth withbefier FCR, chickens do not require to be restricted atmaintenance r€quirement as suggesled by Plavnik and

Huwitz (1985). Dia dilution failed to induce any

compensatory grovtrth. This did not agree with theobs€rvation of Leeson ot al. (1991) who found completecompensatory growth when broilers were fed dilut€d diet.This difference might be partly caused by more sever,e

effcct ofdiet dilutior in the preseDt study.The present study showed that feed rcstriction level

affected the degree ofcompensatory growth and duration offeed restriction tended to exett an effect on it. Santoso(200 I a) also found thal duration and leyel of feed restrictioninfluenced the degree of compensatory grqwth. Less severeand shofter duration of feed restriclion resulted in higherdeg€e of compensatory groMh.

Early feed restriction did not consistently improve FCRin restrict€d broilers at 56 days ofage. To produce completecompensatory growfh with b€tter FC& chickens r€ared incages should be fed 25o/o qd libitun for 6 days. Santoso(2001a) found that broilers reared on-floor could be fed25o/o od libitun for 9 days, indicating that rearing typ€might influence the response of broilers to early fe€dr€striction. It was known that broilers reared on-floor had

better insulation, and thus they could be restric{ed longer. ltseemed that more severe feed restriction would rcsult inbetter FCR. The present shrdy found that broilen receivingmeal feeding or physical restriction showed better FCR as

aompared vrith diet dilution. This result was contrary to theobservation ofSu et at. (1999) who found that meat feedingresulted in b€tter FCR ratio than physical feed restriction inbroilers. Although it was nol significantly different, itappears that early feed restriction started at 2 days of age

had better FCR than the othe$.As pointed out by Ballay et zl. (1992) ad libitum

feeding of broilers might be detrimental bmause of highermortality- Results of the present study confirmed thatobservation (Experiment 1). Holyev€r, tho proscnt studyproved that early feed restriction did not consistently r€duco

mortality. The prcsent study also confirms that early f€€drestsiction could rcduce leg abnormalities as observed iaother investigatiotrs (llester et al., 1990; Robinson et al.,1992). Lower protein intake in restricted broilers duringrestriction period might contribute to lower leg abnormalityin restricted broilors. Hulan et al- (1980) found that lowerprotein intake would reduce leg abnormalities.

T)?es of restrictio also influenced the occurrence of In order to echi€ve the best results from the early feedcompensatory gtowth. Meat feeding showed higher resfiction, it was concluded from Experiment I that

a

broilers should be restria-fed at 25o/o ad libitun for 6 days.Meal feeding starEd at 2 days of age showed the bestperformance @xperiment 2).

ACKNOWLEDGEMENTS

We gratefully acknowledge research grant fromDirectorate General for Higher Education ofthe Ministry ofEducation and Culture (DGHE), Indonesia through URGELoan IBRD-No. 3754-IND.

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EARLY FEED RESTRICTION AND COMPENSATORY GROWTH IN BROILERS