Gene . Sel. E ol. 38 (2006) 389–409 389
c
INRA, EDP Sciences, 2006
DOI: 10.1051/gse:2006011 O iginal a icle
Reco ding s a egies and selec ion po en ial
o eed in ake measu ed using he X- ay
me hod in ainbow ou
An i Ka∗, Declan Tb, Alexand e Db∗∗,
Dominic Hb,SamMb,EsaA.M
¨
a,
Ossi Rc,Ka iRd
aMTT Ag i ood Resea ch Finland, Animal P oduc ion Resea ch, Animal B eeding,
FIN-31600 Jokioinen, Finland
bSchool o Biological Sciences, Depa men o Zoology, Uni e si y o Abe deen, Abe deen,
AB24 2TZ, Uni ed Kingdom
cFinnish Game and Fishe ies Resea ch Ins i u e, Te o Fishe ies Resea ch and Aquacul u e,
FIN-72210 Te o, Finland
dFinnish Game and Fishe ies Resea ch Ins i u e, Tu ku Game and Fishe ies Resea ch,
FIN-20520 Tu ku, Finland
(Recei ed 4 No embe 2005; accep ed 27 Ma ch 2006)
Abs ac – This s udy examines he way long- e m eed in ake should be eco ded accu a ely
o selec i e b eeding pu poses, and es ima es selec ion po en ial in eed in ake using he X-
ay me hod o eco d indi idual daily eed in ake in ainbow ou (Onco hynchus mykiss).
The analysis showed ha he poin es ima es o daily eed in ake displayed low epea abili-
ies ( =0.09−0.32). This indica es ha a minimum o h ee epea ed eco ds we e needed o
accu a ely eco d a e age eed in ake a a ixed age. To effec i ely b eed o eed in ake o e he
whole g owing pe iod, i is necessa y o de e mine a e age eed in ake a diffe en ages, since
he e we e only mode a e pheno ypic and gene ic co ela ions be ween a e age daily eed in ake
eco ded a 140 g, 750 g and 2000 g we mass. He i abili y o a e age daily eed in ake was
low (a e age h2=0.10), indica ing ha modes gene ic changes can be ob ained in esponse
o selec ion. I was concluded ha selec ion o gene ically change long- e m eed in ake can be
success ul, ye epea ed obse a ions a se e al li e s ages a e needed o ensu e he accu acy o
eed in ake es ima es and he efficiency o selec ion.
eed efficiency /X- adiog aphy /he i abili y / epea abili y /salmonids
∗Co esponding au ho : [email p o ec ed]
∗∗ Cu en add ess: Uni o Social Ecology, Uni e si é Lib e de B uxelles, CP 231, Bd du
T iomphe, 1050, Belgium.
A icle published by EDP Sciences and a ailable a h p://www.edpsciences.o g/gse o h p://dx.doi.o g/10.1051/gse:2006011
390 A. Kause e al.
1. INTRODUCTION
Feed is one o he majo cos s in a m animal p oduc ion. In aquacul u e,
imp o ing eed efficiency, a a io o we mass gain o eed in ake, would ha e
he effec o educing eed cos s and minimising en i onmen al loading. Selec-
i e b eeding is a po en ial ool o imp o ing eed efficiency. Feed efficiency
can be imp o ed by simul aneous selec ion o apid g ow h and agains eed
in ake, o , when g ow h a e and eed efficiency a e a ou ably gene ically co -
ela ed, by sole selec ion o inc eased g ow h a e [21]. Since eed in ake is
a undamen al componen o eed efficiency, eliable means o eco ding eed
in ake a e equi ed. This s udy examined he way long- e m eed in ake should
be eco ded in ainbow ou (Onco hynchus mykiss Walbaum) o selec i e
b eeding pu poses, and es ima ed selec ion po en ial in eed in ake.
In o de o be able o es ima e he gene ic po en ial o selec ion, indi idual
eed in ake needs o be eco ded in a amily-s uc u ed popula ion. Fo h ee
easons, an accu a e eco ding o indi idual eed in ake o e he whole g ow-
ing pe iod is challenging in g oups o ish. Fi s , eed in ake o indi iduals
a ies g ea ly om day- o-day in salmonids e.g. [15, 28]. The obse ed high
a iabili y educes he abili y o p edic long- e m eed in ake o an indi idual
using a single daily eco d [16]. Because i is known ha measu emen accu-
acy can be inc eased by eco ding he same indi iduals epea edly [9], i is o
in e es o quan i y he numbe o epea ed daily eed in ake eco ds needed a
each ixed age poin o accu a ely es ima e a e age eed in ake. Second, indi-
idual anking ac oss ages may change. Fo b eeding pu poses, i is o in e es
o know whe he o no ea ly eed in ake measu emen s can be used as eli-
able gene ic p edic o s o e he whole g owing pe iod. I would be emp ing
o measu e eed in ake om young ish because eed in ake is especially la-
bo ious o eco d om la ge ish bu alida ion o his me hod is equi ed. So
a , es ima es o gene ic co ela ions be ween eed in ake eco ded a diffe -
en s ages o he li e cycle ha e no been a ailable o any ish species. Thi d,
eco ding indi idual eed in ake on a la ge numbe o ish held in a common
ank is echnically difficul .
A poin es ima e o indi idual eed in ake om a la ge numbe o ish can
be eco ded by he X- ay me hod [14,16,17,30]. To measu e eed in ake using
he X- ay me hod, all ish held in a ank a e i s ed wi h eed con aining small
glass beads con aining lead oxide. The ea e , he ish a e X- ayed. The num-
be o glass beads consumed can be coun ed om he X- ay ilms. Because he
glass bead con en o he eed is known, i is possible o calcula e he quan-
i y o eed ha each ish consumed [16, 30]. The ques ion emains, howe e ,
Feed in ake in ish b eeding 391
whe he he X- ay me hod would suffice o selec ion pu poses ha a e aimed
a changing long- e m eed in ake las ing o e he whole on-g owing pe iod.
The X- ay me hod was applied he e o a la ge numbe o pedig eed ainbow
ou Onco hynchus mykiss (Walbaum) o examine he ollowing ou opics.
Fi s , i was assessed how many daily eed in ake measu emen s a e needed o
accu a ely es ima e a e age eed in ake o an indi idual a a ixed age. Second,
i was es ed whe he eed in ake displays non-ze o he i abili ies ha would al-
low i s gene ic imp o emen h ough selec ion. Thi d, o s udy whe he eco d-
ing o eed in ake a a single age can be used as a p edic o o e he whole
g owing pe iod up o 2 kg ish, i was assessed whe he a e age eed in ake
measu ed a diffe en ages co ela e posi i ely. Finally, he ish in his s udy
we e ed wi h wo diffe en die s, ha ing diffe en p o ein and lipid con en , o
examine he consis ency o pheno ypic and gene ic pa ame e s ac oss dis inc
nu i ional en i onmen s. Feed in ake o salmonids changes ac oss nu i ional
en i onmen s [7], and in esponse o changes in body composi ion and mass,
e.g.in he o m o compensa o y eeding [15]. Hence, i is possible ha phe-
no ypic and gene ic pa ame e s o eed in ake diffe on al e na i e die s. The
wo die s, a no mal p o ein die (NP) ep esen ing mode n eeds, and an ex-
pe imen al high p o ein die (HP), we e es ablished o speci ically assess he
in luence o die s on pheno ypic and gene ic (co) a ia ion o composi ion ai s
(de ailed by Tobin e al., in p ep.) bu he e he same expe imen al se up was
applied o eed in ake.
2. MATERIALS AND METHODS
2.1. Popula ion s uc u e
The ish used o igina ed om he Finnish na ional b eeding p og amme
(The Selec), ca ied ou a he Te o Fishe ies Resea ch and Aquacul u e s a-
ion (a eshwa e s a ion) o he Finnish Game and Fishe ies Resea ch Ins i-
u e. The ini ial popula ion was es ablished in he la e 1980s by c ossing ou
high quali y s ains. The b oods ock managemen and selec ion p ocedu es a e
desc ibed by Kause e al. [20]. The ish o he p esen s udy we e kep in
eshwa e a he Te o s a ion du ing he whole expe imen (June 2001 un il
No embe 2004).
In o de o s udy he po en ial o selec i e b eeding o eed in ake, he 2001
gene a ion was exposed o wo diffe en die ea men s in a spli - amily design.
In Ap il 2001, a o al o 89 si es and 109 dams we e ma ed in a ac o ial design
o p oduce 210 ull/hal -sib amily g oups. Each si e was ma ed o an a e age
392 A. Kause e al.
Table I. Popula ion s uc u e and a e age amily size o a o al o 210 amilies sam-
pled a h ee eco ding imes.
165 amilies 45 amilies
Numbe o si es and dams 81, 99 34, 40
Family size, ime 1 (1s X-Ray) 6.6 30.9
Family size, ime 2 (2nd X-Ray) 5.4 26.6
Family size, ime 3 (3 d X-Ray) 4.4 13.4
o 2.3 dams ( ange: 1–5) and each dam o 1.9 si es ( ange: 1–3). The ma ings
las ed h ee days. The pedig ee o e e y ish was known om he gene a ions
bo n in 1998, 1995, 1992 and 1989.
The eggs we e incuba ed in he same incuba o , bu amilies we e kep sep-
a a ed. The eye-s aged eggs we e ans e ed o indoo 150 L amily anks in
June 2001. Each o he 210 amily was held in hei own ank.
In Feb ua y 2002, a e 8 mon hs o g owing in he amily anks,
2931 inge lings we e emo ed om he anks and indi idually agged wi h
PIT- ansponde s (T o an L d, Ge many) o enable indi idual iden i ica ion.
Fo 165 o he 210 amilies, an a e age o 7.0 ish pe amily we e agged
( ange 4–7 ish). F om he emaining 45 amilies, an a e age o 39.6 ish pe
amily ( ange 37–40 ish) we e agged. The la ge ini ial amily size was chosen
because hese amilies we e des uc i ely sampled o muscle and body com-
posi ion o o he pu poses han his s udy. The change in he a e age amily
size ac oss he h ee sampling imes is shown in Table I. Be o e he ini ia ion
o he die ea men s, all ish we e ed wi h comme cial ainbow ou d y eed
(Nu a S a e and Nu a Pa , Rehu aisio Inc., Finland).
2.2. Fish managemen
Du ing agging, ish om each amily we e spli in o wo g oups o be ea ed
on diffe en die s. In May 2002 (week 20) wo die a y ea men s we e ini ia ed.
The die s we e a mode n die wi h no mal p o ein (40–45%) and high lipid con-
en (30–33%) (NP die ), and an al e na i e die wi h high p o ein (50–56%)
and low lipid con en (15–24%) (HP die ) (Tab. II). The die s consis ed o ish
meal, ish oil, whea meal and whea s a ch, and we e supplemen ed o mine -
als and i amins acco ding o he NRC, Na ional Resea ch Council [31]. The
expe imen al HP die was designed so ha he capaci y o inefficien ish o
deposi diges ed p o ein as p o ein g ow h would be g ea ly exceeded, leading
o hei slowe g ow h and highe lipid deposi ion compa ed o he efficiency o
indi iduals. This was hypo hesised o lead o an enhanced selec ion po en ial
Feed in ake in ish b eeding 393
Table II. P oxima e composi ionao no mal p o ein (NP) and high p o ein die s (HP), including glass-bead labelled X- ay die s ed a
measu emen imes 1 (pelle size 3 mm), 2 (size 6 mm) and 3 (size 7 mm).
Feed, pelle size Wa e (%) Ash (%) CL (%) CF (%) CP (%) NFE (%) P (g ·Kg −1)Ene gy(KJ·g−1)
NP, 3 mm 2.1 7.4 30.5 0.73 44.9 15.1 12.1 23.6
NP, 6 mm 1.5 7.7 30.3 0.72 44.6 15.9 12.7 26.0
NP, 7 mm 4.0 6.7 33.4 1.00 39.5 15.4 9.60 25.9
HP, 3 mm 2.3 9.6 20.7 0.44 56.4 11.1 15.5 25.6
HP, 6 mm 1.7 9.5 20.6 0.48 56.3 11.9 15.4 24.0
HP, 7 mm 7.2 8.3 23.8 1.30 49.4 10.0 11.8 23.3
NP, 3 mm (labelled) 6.9 7.5 29.4 0.74 41.1 15.1 11.3 24.3
NP, 6 mm (labelled) 5.6 7.4 31.4 0.72 40.1 15.5 11.2 24.9
NP, 7 mm (labelled) 3.8 6.3 34.3 1.00 40.5 14.1 10.4 25.6
HP, 3 mm (labelled) 7.6 10.4 15.4 0.62 54.2 12.4 15.2 21.1
HP, 6 mm (labelled) 9.4 10.6 14.1 0.55 54.1 11.8 15.1 20.7
HP, 7 mm (labelled) 3.9 9.1 20.6 0.90 55.8 9.70 13.8 22.4
aCL =c ude lipid; CF =c ude ib e; CP =c ude p o ein; NFE =ni ogen- ee ex ac s; P =phospho us.

394 A. Kause e al.
on he HP die , in e ms o inc eased he i abili ies o lipid body composi ion
and mo e a ou able co ela ions be ween g ow h and lipid deposi ion (Tobin
e al., in p ep.).
The ish spli be ween he wo die s we e o simila mass a agging (mean ±
SD: NP =62.4 ±19.9 g, n=1355 and HP =62.3 ±19.4 g, n=1335). Each
die g oup was placed in ou eplica e ib eglass es anks and housed indoo s.
Fish we e kep in 3 m3 anks un il week 24 and ans e ed o 20 m3 anks
he ea e . The amilies we e equally dis ibu ed among he anks. Fish densi y
in each ank emained unde 20 kg ·m−3.
Feeding was au oma ed using compu e -con olled pneuma ic eede s
(A o-Tec Inc., Finland). Daily eeding a ion was based on con inuous em-
pe a u e measu emen s and he g ow h o mula o ainbow ou based on
an op imum g ow h empe a u e o 16 ◦C. Sligh o e eeding wi h 10–20%
eed gi en o e he ecommenda ions was applied du ing he expe imen o
p e en a es ic ion o g ow h po en ial o he ish. Wa e empe a u e du -
ing he expe imen was ambien and exposed o seasonal luc ua ions ( ange =
0.4−22.9◦C). Oxygen concen a ion was kep o e 6.0 mg ·L−1and a cons an
pho ope iod o 16L:8 D was used.
2.3. Reco ding ai s
Daily eed in ake and body mass we e eco ded on h ee occasions; May
2002 ( ime 1, a 140 g), Oc obe 2002 ( ime 2, a 750 g), and Sep embe 2003
( ime 3, a 2000 g). The iming o a ai eco ding is indica ed by a subsc ip
o he ai name. The esul s o body mass a e b ie ly summa ised he e o
compa e he eed in ake esul s wi h a ai o which beha iou is al eady well
unde s ood and documen ed [19,20].
Each eco ding ime, 1, 2 and 3, consis ed o a 3-week session wi h h ee
epea ed weekly measu emen s o bo h body mass and daily eed in ake. Du -
ing a 3-week session, each ank was measu ed once a week, measu ing wo
anks pe day in a consis en o de each week. Due o he measu emen con-
s ain s o eed in ake ials, he es anks we e di ided in o wo eeding
g oups ( wo NP and wo HP anks pe g oup), one g oup being ed om 0400
o 0800 h and he o he g oup om 0800 o 1200 h. On successi e days he
eco ding o de o NP and HP anks was e e sed, o a oid he effec s o sys-
ema ic eeding hy hms. In o he wo ds, on Tuesday mo nings one NP and one
HP ank we e measu ed successi ely, on Wednesday mo nings one HP and one
NP ank we e measu ed successi ely, e c. To ini ia e a session, all ish we e
weighed du ing he i s week o each session, and p ede e mined andomly
Feed in ake in ish b eeding 395
chosen ish om each amily we e eco ded o eed in ake using he X- ay
me hod. Du ing he second and he hi d weeks, only he ish X- ayed du ing
he i s week we e weighed and X- ayed again.
The X- ays we e pe o med in he same way o all anks and du ing
all sessions. Indi idual eed in ake was eco ded by X- adiog aphy using a
po able X- ay uni (Todd Resea ch 80/20, UK), as desc ibed by Talbo and
Higgins [38] and McCa hy e al. [30]. P io o X- ay, all ish om a gi en
ank we e ed as usual bu he die was labelled wi h adio-opaque ballo ini
glass beads (Jencons Scien i ic L d, Leigh on Buzza d, UK) (Tab. II). The la-
belled pelle s used a imes 1, 2 and 3 consis ed o 1%, 0.5% and 0.3% beads
wi h a diame e o 400–600 µm, espec i ely (i.e.43–45 beads ·g−1o d y
eed a ime 1, 12–17 beads ·g−1o d y eed a ime 2, 7–12 beads ·g−1o
d y eed a ime 3). A minimum o 2 h a e he eede s had s opped p o id-
ing eed, he ish o be eco ded we e se ially placed in o anaes he ic solu ion
(buffe ed MS-222), weighed and X- ayed. A e X- aying, he ish we e e-
u ned o hei espec i e anks. The ea e , he beads we e coun ed om he
ilms, and he mass o eed wi hin a s omach was es ima ed using a calib a ion
eg ession equa ion. A calib a ion line was cons uc ed o each session and
each die sepa a ely. This was done by X- aying diffe en bu known amoun s
o eed (n=minimum o 8 eed samples pe die ), and hen by eg essing
he numbe o beads coun ed agains he known eed mass (R2=0.90–0.99).
Mo eo e , sepa a e expe imen s we e pe o med o ind an app op ia e du a-
ion o he eeding pe iod and o he iming o he X- ays o a oid e acua ion
o he eed wi h beads be o e X- aying he ish (da a no shown).
The ish we e eco ded o sex and ma u i y in May 2003 h ough isual
inspec ion o seconda y sexual cha ac e s, and in No embe 2003 by he ex-
amina ion o gonads om slaugh e ed ish. The ish we e classi ied in o six
sex/ma u i y g oups; males we e classi ied as ma u e a 2, 3, o la e yea s, e-
males as ma u e a 3 o la e yea s, and all o he ish as indi iduals o unknown
sex and ma u i y age.
2.4. Repea abili y and accu acy o eco ds
Repea abili ies we e calcula ed o es ablish he consis ency o daily eed
in ake eco ds in each die and each h ee-week X- ay session. When e-
pea ed eco ds o each indi idual a e a ailable, pheno ypic a iance (VP)is
composed o VP=VG+VEg+VEs,whe eVG e e s o gene ic a iance,
VEg o gene al en i onmen a iance, and VEs o he wi hin-indi idual a i-
ance a ising om epea ed measu emen s. Repea abili y was calcula ed as
396 A. Kause e al.
=1−VEs/VP[9] and i s s anda d e o as desc ibed by Becke [3]. The
accu acy o obse a ions is inc eased by calcula ing he mean o n epea ed
eco ds measu ed o each indi idual. This educes VEs by a ac o o 1/n
and consequen ly educes he pheno ypic a iance o he mean alues (Vmean).
Thus, he a io o Vmean o VPis a measu e o a gain in he accu acy om
epea ed eco ds. The change in accu acy (in uni s o %) was calcula ed as
100−100[1 + (n−1)]/n[9]. Fu he mo e, a epea abili y o he mean o n
epea ed eco ds was calcula ed as mean =n /[1 +(n−1) ].
2.5. Leas squa es means
The ish we e eco ded o body mass and daily eed in ake one o h ee
imes du ing each 3-week X- ay session. Because some ish lacked one o
wo o he h ee eco ds and because he e we e diffe ences among he a e -
age weekly ai means, he aw means o each indi idual would ha e been
unsui able o he subsequen calcula ions. The e o e, weigh ed leas squa es
means o each indi idual we e ob ained by accoun ing o he es ank-wise
weekly pe o mance. This was pe o med o each ank sepa a ely by i ing
an analysis o a iance o he longi udinal eed in ake da a wi h a model in-
cluding indi idual ish (all ish wi hin a gi en es ank) and es week (weeks
1, 2, and 3) as ac o s, and calcula ing leas squa es means o each indi idual
(LSMeans op ion, SAS
So wa e, Ca y, NC). These weigh ed means o he
indi iduals we e used as obse a ions in he subsequen s a is ical and gene ic
analyses.
2.6. S a is ical es s o die diffe ences
In o de o examine he diffe ences be ween he die s in body mass and eed
in ake, pa ame ic analyses o a iance we e pe o med on he leas squa es
means o indi idual eco ds (p ocedu e P oc Mixed, SAS
So wa e). The
ixed effec s included in he model we e die , sex/ma u i y class, and in e ac-
ion o die wi h sex/ma u i y. The andom ac o s included we e amily ( his
consis s o bo h common en i onmen effec and gene ic effec o he 210 am-
ilies), es ank nes ed wi hin die , in e ac ion o amily wi h die , in e ac ion o
amily wi h sex/ma u i y class, and in e ac ion o es ank wi h sex/ma u i y.
Tes ank was conside ed o be a andom ac o in he Ano a o be able o gen-
e alise he esul s o include o he es en i onmen s. The me hod o Kenwa d
and Roge [22] was used o calcula e co ec F- es s and hei deg ees o ee-
dom o he ixed effec s. A e age eed in akes we e squa e oo - ans o med o
Feed in ake in ish b eeding 397
ob ain no mally dis ibu ed esiduals o he models. When calcula ing s a is-
ical es s and leas squa es means o ela i e eed in ake (a e age eed in ake
co ec ed o body mass), body mass was included as a co a ia e in he models
o a e age eed in ake. This ai is he e e e ed as eed in ake %.
2.7. Gene ic analyses
(Co) a iance componen s we e es ima ed om he leas -squa es means o
indi idual eco ds using a e age in o ma ion (AI) es ic ed maximum likeli-
hood me hod o he DMU so wa e [13].
A ai measu ed on he wo die s was ega ded as wo diffe en ai s. The
model o he die -speci ic eed in akes and body mass was he ollowing:
yijkl =animi+ am ank j+SEXMATk+TESTTANKl+εijkl,
whe e animiis a andom gene ic effec o an animal (i=1... numbe o obse -
a ions), am ank jis a andom amily ank effec (j=1–210), SEXMATkis a
ixed sex and ma u i y effec (k=1–6), TESTTANKlisa ixed es ankeffec
(l=1–4 anks), εijkl is he esidual, and yijkl is an obse a ion o an indi id-
ual. Tes ank is conside ed o be a ixed ac o in he gene ic analysis because
we wan o emo e i s effec on pheno ypic a iance and because o he low
numbe o es anks. Fo eed in akes eco ded a imes 2 and 3, he andom
amily ank effec was negligible, and i was emo ed om he model. To cal-
cula e gene ic pa ame e s o ela i e eed in ake ( eed in ake %), body mass
was included as a co a ia e o he models o a e age eed in ake.
Using hese models, gene ic (VG), common en i onmen (V am ank), esid-
ual (VR) and pheno ypic a iances (VP=VG+VR+V am ank), as well as
pheno ypic ( P) and gene ic co ela ions be ween ai s ( G) we e ob ained.
He i abili y was calcula ed as h2=VG/VPand common en i onmen a io as
c2=V am ank/VP. Common en i onmen (co) a iance includes effec s due o
sepa a e ea ing o ull-sib amilies un il agging, bu also pa s o dominance
effec s. Gene ic (co) a iances, es ima ed by he animal effec , include addi i e
gene ic (co) a iance bu also pa s o dominance (co) a iance. Consequen ly,
he s a is ical model used does no allow us o ge a clean (isola ed) es ima e
o he addi i e gene ic (co) a iances. Ra he , gene ic a iances, he i abili ies
and gene ic co ela ions es ima ed he e a e b oad-sense es ima es. To scale he
pheno ypic a iance o ai s wi h diffe en means (x), coefficien o pheno-
ypic a ia ion was calcula ed as CVP=√VP/x. App oxima e s anda d e o s
o (co) a iances we e ob ained by a i s -o de Taylo se ies expansion o he
AI ma ix o he es ima ed (co) a iances [13]. The s anda d e o s o he i abil-
i ies, gene ic co ela ions, and CV we e calcula ed ollowing Becke [3].
404 A. Kause e al.
conside able eco ding noise o he long- e m eed in ake, he me hod is s ill
accu a e o he pu poses o sho - e m physiological and beha iou al s ud-
ies las ing a ew days. I is well es ablished ha he X- ay me hod accu a ely
desc ibes he ue daily eed in ake [28,30].
I would be bene icial o ob ain highe epea abili ies o eed in ake, e.g.
using imp o ed eco ding me hods, o by eco ding eed in ake h oughou
on-g owing, as is done in a m animals. A ace elemen me hod in which a
ma ke included in eed accumula es in he ish body has been used in ish and
may p o e o be a use ul al e na i e o eco d in ake o longe pe iods o ime
e.g.[10, 24]. In a m animals, a e age daily eed in ake is ypically eco ded
du ing each day o a long es ing pe iod, in some cases o e he whole p oduc-
ion ime (e.g., in pigs). Fo ins ance, he es ing pe iod has been 35–100 days
o pigs [33,35], 70–119 days o ca le [1,2], 42–56 o lambs [4,11,37], and
23–182 days o chicken [5, 34]. In compa ison, in he p esen s udy eed in-
ake was eco ded a each age only du ing h ee days, ye o e a 21-day es ing
pe iod. A che e al. [1] showed how e o a iance is d ama ically dec eased
when he es ing pe iod is p olonged om 7 days o 119 days in ca le. An im-
p o ed eed in ake eco ding in ish would lead o mo e eliable es ima es o
ea men means, indi idual eed in akes, gene ic pa ame e s, a educed need
o se e al epea ed eco ds, and an inc eased powe o s a is ical es s due o
educed e o a iance.
Pheno ypic and gene ic co ela ions be ween a e age eed in akes eco ded
a diffe en ages we e only mode a e. The highes co ela ions we e be ween
successi e ages, indica ing ha some a ou able co ela ed gene ic esponses
a e expec ed when selec ing only o one ai . I a e age eed in ake is o be
eco ded a a single occasion, hen ma ke -sized ish (>750 g) should be p e-
e ed. This is because ea ly measu emen s aken om 140 g ish canno be
used as eliable p edic o s o e he whole g owing pe iod. The esul s show
u he ha i one a emp s o effec i ely b eed o long- e m eed in ake, se -
e al eco ds a e needed om ish o diffe en ages. In line wi h ou inding
on he e- anking o amilies ac oss ages, Thodesen e al. [39] showed ha
ela i e eed in ake o selec i ely b ed A lan ic salmon is highe han ha o
wild salmon only du ing he ea ly s ages o g ow h (when g own om 814 g
o 1455 g), e ealing a s ain-by-age in e ac ion.
4.2. He i abili y o eed in ake
The he i abili y o a e age eed in ake was low (a e age h2=0.10),
he highes indi idual alue being 0.17. Consequen ly, he e is sufficien

Feed in ake in ish b eeding 405
gene ic a ia ion o be used o selec i e b eeding, bu clea ly less han o
body mass [19, his s udy]. He i abili ies o eed in ake in poul y (a e age
0.45, [32]), pigs (0.29, [6]), sheep (a e age 0.36, [4,11,37]), and ca le (a e -
age 0.41, [26]) a e highe han epo ed he e, p obably e lec ing he ac ha
eed in ake displays less unexplained esidual a ia ion and eed in ake eco ds
a e mo e eliable in a m animals.
Wi h he excep ion o Sil e s ein e al. [36], p e ious s udies on he ge-
ne ics o eed in ake in ish ha e been based on amily mean eco ds. Each
ull-sib amily has been kep in hei own (o eplica ed) anks, and he ank-
mean eed in ake has been eco ded. As s essed by Doupé and Lymbe y [8],
he d awback o his app oach is ha by calcula ing he amily means, he
g ea wi hin- amily a ia ion exis ing in ish is excluded om he da a. He -
i abili ies and p opo ion o a ia ion due o amily om such s udies ange
om 0.31–0.84 [23,25,40] bu hese a e o e es ima es due o he amily mean
me hod. Sil e s ein e al. [36] ound a he i abili y o 0.37–0.41 o indi idual
eed in ake eco ds o ca ish. The highe he i abili y compa ed o he p esen
s udy may be due o species diffe ence o diffe ences in expe imen al design.
Fo ins ance, Sil e s ein e al. used a ull-sib design in which case en i on-
men al effec s common o ull sibs end o aise he i abili y es ima es.
In pigs, a he ea ly s ages o g ow h when pigs mainly deposi p o ein, low
eed in ake may be es ic ing hei g ow h. In con as , as pigs age, olun a y
eed in ake g ea ly exceeds ene gy equi emen s, and hus, educes eed effi-
ciency and inc eases lipid deposi ion [35,41]. Acco dingly, he aim o gene i-
cally changing eed in ake is no always o educe i . In a m animals, andom
eg ession me hods ha e been applied o simul aneously analyse all sepa a e
eed in ake eco ds o e he whole li e span, in o de o con ol he gene ic
changes occu ing a diffe en ages [33, 35]. Applying he andom eg ession
me hod o indi idual daily eco ds appea s difficul in salmonids. This is due
o he high day- o-day a iabili y o eed in ake, in which case, o example,
eed in ake o some indi iduals has nega i e eg ession slopes e en hough
hese indi iduals a e g owing s eadily du ing a es pe iod.
4.3. Die effec s on eed consump ion and epea abili ies
Fish on he HP die had highe a e age eed consump ion han ish on he NP
die wi h wo, o mo e, explana ions. Fi s , ish ed he HP die may be de icien
in lipid o ene gy (and hey a e o smalle size) and he e may ha e been an
a emp o compensa e o his by eeding mo e. I has p e iously been shown
ha ish ac i ely compensa e o educed lipid s o es and small body size by
406 A. Kause e al.
inc easing eed and ene gy in ake e.g.[17,18]. Second, wi h he NP die he e
was no equi emen o inc ease eed in ake o mee he ex a p o ein demand
associa ed wi h g ow h. This is because he excess lipid in he die may ul il
ene gy equi emen s, hus allowing ish o spa e p o ein o he pu poses o
g ow h, leading o a p o ein spa ing effec [12]. Mo eo e , epea abili ies we e
highe wi h he HP die . This may be a esul o he highe o e all consump ion
o ha die .
To conclude, he analyses o he daily eed in ake da a eco ded using he
X- ay me hod p o ed ha selec ion o gene ically change long- e m eed in ake
can be success ul, ye epea ed obse a ions a se e al li e s ages a e needed o
ensu e he accu acy o eed in ake es ima es and he efficiency o selec ion.
ACKNOWLEDGEMENTS
Tuija Paananen, Heli Wahl oos, Ángel Ruiz Bañón and Césa Luis
Bo egue o helped in da a collec ion and p epa a ion. No alab L d. conduc ed
he chemical analysis o he eeds. Rob Doupé and an anonymous e e ee p o-
ided help ul commen s on he p e ious e sions o he ex . You a e all g ea ly
acknowledged. This wo k has been ca ied ou wi h he inancial suppo om
he Commission o he Eu opean Communi ies, Quali y o Li e and Manage-
men o Li ing Resou ces P og amme, p ojec Q5RS-2001-0994 “P o ein and
G ow h Efficiency in Salmonid Selec ion (PROGRESS)”. I does no e lec i s
iews and in no way an icipa es he Commission’s u u e policy in his a ea.
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