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Using body measu emen s o es ima e li e weigh
o dai y ca le in low-inpu sys ems in Senegal
S anly Fon Tebug, Ayao Missohou, Souahibou Sou okou Sabi, Ja mo Juga,
Elizabe h Jane Poole, Miika Tapio & Ka en Ma shall
To ci e his a icle: S anly Fon Tebug, Ayao Missohou, Souahibou Sou okou Sabi, Ja mo Juga,
Elizabe h Jane Poole, Miika Tapio & Ka en Ma shall (2016): Using body measu emen s o
es ima e li e weigh o dai y ca le in low-inpu sys ems in Senegal, Jou nal o Applied Animal
Resea ch, DOI: 10.1080/09712119.2016.1262265
To link o his a icle: h p://dx.doi.o g/10.1080/09712119.2016.1262265
© 2016 The Au ho (s). Published by In o ma
UK Limi ed, ading as Taylo & F ancis
G oup
Published online: 08 Dec 2016.
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Using body measu emen s o es ima e li e weigh o dai y ca le in low-inpu sys ems
in Senegal
S anly Fon Tebug
a
, Ayao Missohou
b
, Souahibou Sou okou Sabi
b
, Ja mo Juga
c
, Elizabe h Jane Poole
a
, Miika Tapio
d
and
Ka en Ma shall
a
a
The In e na ional Li es ock Resea ch Ins i u e, Nai obi, Kenya;
b
Se ice de Zoo echnie-Alimen a ion, Ecole In e -E a s Des Sciences E Médecines
Vé é inai es (EISMV) de Daka , Daka , Sénégal;
c
Depa men o Ag icul u al Sciences, Uni e si y o Helsinki, Helsinki, Finland;
d
Na u al Resou ces
Ins i u e Finland (Luke), G een echnology, Jokioinen, Finland
ABSTRACT
We in es iga ed he p edic ion o li e weigh (LW) o dai y ca le in low- o medium-inpu sys ems in
Senegal, based on measu emen s o hea gi h (HG) and heigh a he wi he s (HW). A o al o 459
emale dai y ca le, mainly comp ising indigenous Zebu and hei c osses wi h Guze a o Bos Tau us,
we e weighed (kg), and hei HG (cm) and HW (cm) de e mined. Fa me s we e asked o p o ide hei
own weigh es ima es o each animal. The single explana o y a iable ha explained he mos
a ia ion in LW was HG. The bes model o p edic LW om HG o he o e all da a was
LW =4.81 HG −437.52 wi h an adjus ed R
2
o 0.85 and a oo mean squa e e o o 34.25 kg
co esponding o 11.10% o he mean LW. This model p edic ed he LW o 91–100% o cows and 64–
100% o hei e s wi hin 20% o hei ue-li e weigh , in he weigh ange o abou 100–500 kg. In
compa ison, a me s could only es ima e he LW o abou a qua e o hei animals wi hin 20% o hei
ue LW. This weigh p edic ion equa ion, when ansla ed in o a weigh band, could p o ide a simple
and eliable me hod o ca le keepe s o es ima e he weigh o s udied ca le b eed ypes.
ARTICLE HISTORY
Recei ed 7 June 2016
Accep ed 11 No embe 2016
KEYWORDS
Dai y ca le b eed; weigh
es ima ion; hea h gi h;
heigh a wi he s
1. In oduc ion
The accu a e es ima ion o body weigh o li es ock is impo -
an in deciding he slaugh e weigh , eeding le el and wha
ea men dose o use (Ulu as e al. 2002; Machila e al. 2008).
Among he many me hods used o i s de e mina ion, a weigh-
ing scale is conside ed he gold s anda d i he scales used a e
well calib a ed (Machila e al. 2008). In mos u al a eas o A ica,
ca le a e a ely weighed as weighing ins umen s a e cos ly o
ob ain, need echnical main enance and a e di icul o ans-
po o li es ock a ms, especially in pas o al and ag o-pas o al
sys ems (Machila e al. 2008). Fa me s and ca le ade s o en
ely on isual judgemen o de e mine he li e weigh (LW) o
animals, which is a subjec i e me hod whose accu acy
depends on use s’expe ience.
Body weigh is closely ela ed o body measu emen s, wi h
HG gene ally accep ed as he mos sa is ac o y single p edic o
o LW in ca le (Fall e al. 1982; Dodo e al. 2001; Yan e al. 2009;
Isik e al. 2009; Lesosky e al. 2012; Lukuyu e al. 2016). The
me hod is cheap, accu a e and consis en ; hus, many p edic-
i e eg ession equa ions a e based on his pa ame e alone
o in combina ion wi h o he s. Whils such s udies ha e been
ca ied ou in Senegal – he ocal coun y o his s udy –in
he pas (Chollou e al. 1978; Fall e al. 1982; Buldgen e al.
1984), hey a e mo e han 30 yea s old and may no be alid
o he new c oss and pu e ca le b eed ypes ha a e eme ging
in Senegal, p ima ily h ough he use o exo ic b eed ypes ia
a i icial insemina ion.
The objec i es o his pape we e (1) o de elop a p edic ion
equa ion o body weigh es ima ion om body measu emen s
ac oss di e en ca le b eeds and c oss-b eeds cu en ly
p esen in selec ed low-inpu ca le sys ems in Senegal, which
could la e be ansla ed in o a weigh band o use by a me s
and (2) o assess he accu acy wi h which a me s in hese
sys ems es ima e he weigh o hei ca le.
2. Ma e ials and me hods
2.1. P ojec
This s udy was pa o he Senegal Dai y Gene ics p ojec ,
whose aim is o imp o e dai y p oduc ion and p oduc i i y in
Senegal h ough he use o he mos app op ia e b eed ypes. I
is pa o he la ge Food A ica p og amme aimed a imp o ing
ood secu i y in Wes and Eas A ica (see h ps://po al.m . i/
po al/page/po al/m _en/p ojec s/ ooda ica).
2.2. S udy si es
Thiès and Diou bel egions o Senegal had been chosen o he
la ge p ojec because o he di e si y o ca le b eed ypes in
hese egions. The clima e in bo h egions is o he Sahelian
ype cha ac e ized by a sho we season ha spans om July
o Oc obe . Annual ain all a ies, wi h an a e age o
662.9 mm (Fall e al. 2006). The li es ock p oduc ion sys em is
mainly ag o-pas o al. Ca le a e mainly g azed on na u al
© 2016 The Au ho (s). Published by In o ma UK Limi ed, ading as Taylo & F ancis G oup
This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License (h p://c ea i ecommons.o g/licenses/by/4.0/), which pe mi s un es ic ed use, dis i-
bu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed.
CONTACT S anly Fon Tebug [email p o ec ed]; s anly [email protected] The In e na ional Li es ock Resea ch Ins i u e, PO 30709, Nai obi 00100, Kenya
JOURNAL OF APPLIED ANIMAL RESEARCH, 2016
h p://dx.doi.o g/10.1080/09712119.2016.1262265
pas u es and occasionally ecei e c op esidues a he end o
he ha es ing pe iod as well as eed concen a es du ing he
d y season.
2.3. Da a
This s udy was implemen ed be ween No embe 2013 and
June 2015 on 484 emale ca le om 84 ca le-keeping a ms
in Thiès and Diou bel egions o Senegal. He d we e selec ed
based on hei he d composi ion, o ensu e ca le om all exis -
ing b eed ypes we e ep esen ed. Da a we e ob ained om
each animal: a me -es ima ed li e-weigh in kg; measu ed LW
in kg; hea h gi h (HG) measu emen in cm and heigh a he
wi he s (HW) in cm. LW was de e mined using an elec onic
ca le scale (Iconix FX1 digi al indica o , Senso onic L d, Hamil-
on, New Zealand). HG was measu ed by le ing he animal o
s and wi h i s head in he no mal posi ion and placing an o din-
a y measu ing ape a ound he animal a he poin o he smal-
les ci cum e ence jus behind he o elegs and behind he
hump o Zebu ca le. The ape was pulled sligh ly abou he
animal, igh enough o pull down he hai s bu no o inden
in o he lesh (B an on & Salisbu y 1946). HW was measu ed
using a measu ing s ick (in cm), as he dis ance om he
g ound o he highes poin o he wi he s. Age o each
animal was es ima ed in yea s om isual assessmen o e up-
ion and wea o ee h and a me ecall, and a b eed g oup was
assigned o each animal. Measu emen s we e aken in he
mo ning o animals ha we e s able- ed, o be o e animals
we e aken o he pas u es o hose g azed on pas u es. All
animals expe ienced a easonable p e-weighing as pe iod
wi h li le a ia ion due o gu - ill a he ime o measu e. To
ensu e a consis en me hodology, all measu emen s we e
aken by he same pe son.
S udy ca le we e assigned o ou main b eed g oups ei he
on he basis o a me ecall in o ma ion o , whe e a ailable,
geno ype in o ma ion. The b eed g oups (as speci ied u he
inTable 1) a e (1) indigenous Zebu, p edominan ly he Zebu
Gob a and Zebu Mau e b eeds; (2) indigenous Zebu c ossed
wi h Guze a (which will be e e ed o as indigenous Zebu
by Guze a abb e ia ed), whe e Guze a is a ecen ly in o-
duced Zebu b eed de eloped in B azil om he Kank ei
ca le impo ed om India (Ma ian e e al. 1999); (3) indigenous
Zebu c osses wi h ecen ly in oduced Bos Tau us (indigenous
Zebu by Bos Tau us), whe e Bos Tau us animals p edominan ly
comp ise he high milk-yielding b eeds (mainly Mon belia d
and Hols ein F iesians) and (4) indigenous Zebu c osses wi h
a highe le el o Bos Tau us o pu e Bos Tau us (high Bos
Tau us). We asked he a me s o name he b eed ypes o
each o he animal’s g andpa en s, ha is, si e o si e, dam o
si e, si e o dam and dam o dam. The animal’s p opo ion o
ancien (indigenous) Zebu (AZ), ecen Zebu (RZ), ancien
Tau ine (AT) and ecen Tau ine (RT) we e hen de e mined,
and based on his he animals we e assigned a b eed g oup
acco ding o he c i e ia in Table 1. Geno yping was pe o med
on 128 o he measu ed animals using he Bo ine 50 K single
nucleo ide polymo phism chip ( hese animals we e selec ed
on he basis o being a emale wi h lac a ion eco ds, o he
pu pose o de e mining he milk yield o he di e en b eed
ypes, which will be epo ed elsewhe e). Admix u e (o his
and e e ence da a) was analysed based on p ede ined clus e -
ing in Bayesian Analysis o Popula ion S uc u e BAPS 6.0 (Co -
ande e al. 2008) acco ding o he so wa e ins uc ions. F om
he e he p opo ion o AZ, RZ, AT and RT was de e mined o
each animal, and animals we e assigned a b eed g oup as
pe he c i e ia in Table 1.
Da a om 25 o he 484 measu ed ca le we e excluded om
u he analysis as hei body weigh was less han 100 kg ( o
which no ela ionship be ween LW and body measu emen s
was ound). The inal da ase included obse a ions om 459
animals (345 cows (3 o mo e yea s o age), 114 hei e s (22
less han 12 mon hs o age, 42 be ween 12 mon hs and 23
mon hs o age, and 51 be ween 24 mon hs and 35 mon hs o
age)). The g oups included 270 indigenous Zebu, 58 indigenous
Zebu by Guze a and 46 indigenous Zebu by Bos Tau us, 36
high Bos Tau us and 49 o he s (Table 2).
2.4. Analysis app oach
Summa y s a is ics o he da a a e gi en as means and s anda d
de ia ion (Table 2). Compa ison o means was de e mined by a
one-way analysis o a iance ollowed by Tukey’s hones ly
signi ican di e ence. S a is ical signi icance was assessed a
p< .05. LW, HG and HW we e app oxima ely no mally dis ibu-
ed (Figu e 1).
S epwise eg ession wi h backwa ds elimina ion p ocedu e
was used o de e mine he bes model o p edic ing LW,
based on Akaike’s In o ma ion C i e ion (which conside s
bo h he i o he model and model simplici y). The ull
model comp ised he independen a iables HG and HW as
co- a ia es, and age and b eed as ca ego ical a iables.
Simple linea eg ession was also used o p edic LW om
HG. The adjus ed coe icien o (mul iple) de e mina ion
(adjus ed R
2
) was also gi en o he models, as an indica o
o he amoun o a iance in LW explained by he model.
The oo mean squa e e o (RMSE; he same as he s anda d
de ia ion o he esiduals), and also he RMSE exp essed as a
pe cen o he eal LW, was used an indica o o accu acy o
he eg ession es ima es (Yan e al. 2009; Lukuyu e al. 2016).
Nine y- i e pe cen p edic ion in e als we e de e mined as
he p edic ed alue ± wice he RMSE. The i o he
eg ession models we e also e i ied by checking he esidual
Table 1. C i e ia o b eed g oup de ini ion, o animals assigned o a b eed g oup
by ei he a me ecall in o ma ion o geno ype in o ma ion.
C i e ia o b eed g oup assignmen , based on
p opo ions o AZ, RZ and RT
a
B eed g oup name
Fa me ecall
in o ma ion Geno ype in o ma ion
Indigneous Zebu 1.00 AZ 0.88–0.99 AZ
Indigenous Zebu by
Guze a
0.50–0.75 AZ; 0.25–0.50
RZ
0.39–0.86 AZ; 0.13–0.61
RZ
Indigneous Zebu by Bos
Tau us
0.50–0.75 AZ; 0.25–0.50
RT
0.38–0.84 AZ; 0.13–0.61
RT
High Bos Tau us 0.00–0.25 AZ; 0.75–1.00
RT
0–0.36 AZ; 0.63–0.98 RT
O he s O he b eed ypes o unknown b eed in o ma ion
a
Whe e AZ e e s o ancien (indigenous) Zebu b eeds; RZ, ecen ly in oduced
Zebu b eeds; and RT, ecen ly in oduced Bos Tau us b eeds. AZ b eeds a e
mainly Zebu Gob a and Zebu Mau e, RZ b eeds a e mainly Guze a , and RT
b eeds a e mainly Hols ein F iesians and Mon belia d.
2S. F. TEBUG ET AL.
plo s. All analyses we e pe o med in R (R Co e Team, 2012),
wi h s ep AIC unc ion om he MASS package used o back-
wa d s epwise elimina ion eg ession, and lm unc ion was
used o simple linea eg ession.
3. Resul s and discussion
3.1. Obse ed body measu emen s and hei
co ela ions
Summa y s a is ics o LW, HG and HW o adul and hei e s o
he a ious b eed g oups a e gi en in Table 2. LW, o cows,
anged om 110 o 618 kg, HG om 110 o 213 cm and HW
om 95 o 161 cm. LW, HG and HW we e lowe o cows o
he indigenous Zebu and Zebu by Guze a b eed g oups, in
compa ison o ha o he indigenous Zebu by Bos Tau us and
high Bos Tau us b eed g oups (p< .05). Fo example, indigen-
ous Zebu cows had a mean LW (mean ± SD) o 302.7 (60.9)
kg, whils ha o he high Bos Tau us was 392.2 (113.9) kg.
Simila esul s we e no ound o hei e , howe e , likely due
o he di e en age p o iles o young animals o he di e en
b eed g oups.
The LW ange o cows o he indigenous Zebu b eed g oup
ound in his s udy is compa able o a p e iously epo ed
weigh ange o adul Zebu Gob a in Senegal o 250–350 kg
Table 2. Summa y s a is ics
1
o he inal da a se o measu ed li e weigh (LW), hea -gi h (HG) and heigh a he wi he s (HW), o cows and hei e s o he di e en
b eed g oups
2
.
Indigenous Zebu
Indigenous Zebu by
Guze a
Indigenous Zebu by Bos
Tau us High Bos Tau us O he
NMean SD NMean SD NMean SD NMean SD NMean SD
LW (kg)
Cow 215 302.74
a,b
60.87 40 310.68
a,c
61.90 32 383.19
d
129.35 16 392.25
d
113.94 42 326.36
b,c
78.01
Hei e 55 226.07
a,b,c
71.23 18 200.89
a,d
42.82 14 243.53
b,d,e,
87.96 20 279.25
e,g
125.94 7 281.71
c, ,g
78.93
HG (cm)
Cow 215 153.51
a,b
11.73 40 155.65
a,c
13.90 32 167.56
d
22.00 16 171.31
d
19.95 42 157.33
b,c
13.44
Hei e 55 138.98
a,b,c
15.25 18 134.11
a,d
12.02 14 145.64
b,d,e,
17.50 20 150.70
e,g
25.55 7 150.29
c, ,g
15.1
HW (cm)
Cow 215 117.75
a,b
6.71 40 119.00
a,c
6.43 32 122.62
d
12.94 16 126.00
d
9.76 42 118.62
b,c
7.05
Hei e 55 110.58
a,b,c,d
7.70 18 108.89
a,e, ,g
8.52 14 114.5
b,e,h,i
9.40 20 113.55
c, ,h,j
12.61 7 116.00
d,g,i,j
6.98
1
N= numbe o eco ds; SD = s anda d de ia ion.
2
Means wi hin a ow bea ing he same supe sc ip a e no s a is ically di e en (p> .05).
Figu e 1. F equency his og ams o LW o li e weigh (a), hea h gi h (b) and heigh a he wi he s (c).
JOURNAL OF APPLIED ANIMAL RESEARCH 3
(Missohou e al. 1997). The a e age LW, HG and HW measu es
o cows o high Bos Tau us ound in his s udy we e gene ally
lowe compa ed o 419–781 kg, 176–223 cm and 125–150 cm
epo ed o Hols ein F iesians cows in a de eloped coun y
con ex (Yan e al. 2009), likely due o he lowe eeding le el
o animals in his s udy in compa ison o ha in he de eloped
wo ld, and because he high Bos Tau us g oup in his s udy
we e no always pu e-b ed (see Table 1). A s udy on dai y
ca le in Kenya (Lukuyu e al. 2016) whe e animals mainly com-
p ised he Small Eas A ican Zebu (SEAZ) c ossed a di e en
le els o exo ic b eeds gene ally ga e lowe LW, HG and HW
han ha epo ed he e, e lec ing he di e en s a u es o
he main Zebu ypes in he wo s udies.
The high s anda d de ia ions obse ed o LW, HG and HW
wi hin a pa icula b eed g oup a e also in line wi h p e ious
s udies (Fall e al. 1982; Dodo e al. 2001; Yan e al. 2009), and
would la gely e lec he di e si y o ca le managemen p ac-
ices wi hin ou s udy si es.
Fo all animals, he co ela ion ( ) be ween LW and HG was
high a = 0.92, and he co ela ion be ween LW and HW and
be ween HW and HG was mode a e a = 0.78 and a = 0.77,
espec i ely. The co ela ions epo ed abo e a e simila o
o he s udies ha ound a co ela ion be ween LW and HW o
0.88–0.97 , and a co ela ion be ween LW and HW o HG o
0.65–0.92 in Wes A ica (Chollou e al. 1978; Fall e al. 1982;
Dodo e al. 2001).
3.2. P edic ion o LW
P edic ion equa ions o LW o di e en models, o he
en i e da ase as well as selec ed subse s o animals (sex
and b eed g oups), a e gi en in Table 3. Fo he en i e
da ase , he bes model o p edic LW was LW =4.08 HG +
1.61 HW +1.42 (Age) −520.90 , yielding an adjus ed R
2
o
0.86 and a RMSE o 32.81 co esponding o 11.02% o he
mean LW. The bes models o a ious subse s o da a (which
a ied acco ding o he da a subse ) had an adjus ed R
2
anging om 0.79 o 0.94 and a RMSE anging om 29.27 o
39.24 kg (9.36%–12.33% o he mean LW).
As he aim o his p ojec was o de elop an easy- o-use ool
o p edic LW o animals (wi hin a known p edic ion in e al)
om body measu emen s –such as a body measu emen o
weigh con e sion able o weigh band –we we e in e es ed
in a model wi h a single explana o y a iable and ha could
be used ac oss he ange o ca le ypes p esen in he
s udy si es. The single explana o y a iable ha explained
he mos a ia ion was HG, consis en wi h p e ious s udies
(Dodo e al. 2001; Yan e al. 2009;Lesoskye al.2012;
Lukuyu e al. 2016). P edic ing LW om HG alone, he
model o he o e all da a was LW = 4.81 HG–437.52, which
had an adjus ed R
2
o 0.85, and a RMSE o 34.25 kg co e-
sponding o 11.10% o he mean LW. Thus, basing a ool on
his equa ion would enable a me s o p edic he LW o
emale animals o 100 kg o a leas 500 kg, o wi hin
34.25 kg o he eal LW in 68% o he cases. Figu e 2 shows
a plo o his model in ela ion o ou da a.
A compa ison o p edic ed LW o eal LW, o adul s and
hei e s o he a ious b eed g oups and ia he model
Table 3. Reg ession equa ions p edic ing li e weigh om di e en models, o all animals o selec ed subse s.
G oup o animals Reg ession equa ion Adjus ed R
2
RMSE
a
RMSE as % eal LW
P edic ion ia bes model ( o ha speci ic g oup o animals)
All LW = 4.08 HG + 1.61 HW + 1.42 Age–520.90 0.8585 32.81 11.02
Cow LW = 1.42 HG + 4.32 HW + 1.19 Age–536.06 0.8165 33.51 10.54
Hei e LW = 3.42 HG + 2.30 HW–504.55 0.8820 29.27 12.33
Indigenous Zebu LW = 3.41 HG + 1.42 HW + 1.63 Age–461.27 0.7860 32.31 11.25
Indigenous Zebu by Guze a LW = 3.34 HG + 1.24 HW + 4.56 Age–384.53 0.8276 30.63 11.07
Indigenous Zebu by Bos Tau us LW = 4.70 HG + 1.70 HW–624.06 0.9370 31.58 9.36
High Bos Tau us LW = 5.00 HG–470.17 0.9064 39.24 11.91
P edic ion ia HG only
All LW = 4.81 HG–437.52 0.8465 34.25 11.05
Cow LW = 4.87 HG–444.07 0.8059 34.41 10.82
Hei e LW = 4.39 HG–384.48 0.8611 31.82 13.43
Indigenous Zebu LW = 4.45 HG–384.11 0.7685 33.66 11.72
Indigenous Zebu by Guze a LW = 4.25 HG–357.56 0.8018 33.31 12.04
Indigenous Zebu by Bos Tau us LW = 5.47 HG–543.33 0.9301 33.64 9.96
High Bos Tau us LW = 5.00 HG–470.17 0.9064 39.24 11.91
a
Roo mean squa e e o .
Figu e 2. Rela ionship be ween li e weigh (LW) and hea -gi h (HG) o he
en i e da ase o he equa ion LW = 4.81 HG–437.52, and wi h di e en
symbols used o di e en b eed g oups. The model line is ep esen ed by he
hick solid line, and 95% p edic ion in e als o he model a e ep esen ed by
dashed lines.
4S. F. TEBUG ET AL.

LW =4.81HG −437.52, showed ha , on a e age, cows o he
indigenous Zebu and indigenous Zebu by Guze a b eed
g oups ha e hei weigh nei he s ongly unde - o o e es i-
ma ed, whils cows o indigenous Zebu by Bos Tau us, high Bos
Tau us and o he b eed g oups ended o ha e hei weigh
unde es ima ed (by 7.36, 4.76 and 7.10 kg, espec i ely). Hei e s
o all b eed g oups ended o ha e hei weigh o e es ima ed,
by 3.64–11.26 kg depending on he b eed g oup (Table 4).
Ac oss he di e en b eed g oups, he pe cen ages o cows
whose weigh was p edic ed wi hin 20%, 10% o 5% o hei
ue LW was a leas 91%, 59% and 35%, espec i ely. Fo
hei e s, hese igu es we e lowe a 77%, 55% and 34% (exclud-
ing he indigenous Zebu by Bos Tau us hei e s, which had pa -
icula ly low alues o 64%, 50% and 21%), pa ly a ibu able o
he lowe weigh s o younge emales (Table 4). These pe cen-
ages, and pa icula ly hose o hei e s, we e lowe han he
70% o animals wi hin 10%, and 41% wi hin 5%, epo ed o
LW es ima ion om HG measu es in 24 mon hs old N’dama
ca le aised on a esea ch a m in Senegal (Fall e al. 1982).
This, howe e , is o be expec ed gi en he a ie y o b eeds,
ages o animals and managemen p ac ices included in ou
s udies compa ed o ha o he Fall e al. (1982) s udy.
Es ima ion o ca le weigh o wi hin 20% o hei ue weigh
is conside ed as an accu acy ange o e e ina y d ug dosing
(Machila e al. 2008; Lesosky e al. 2012). Fo cows, his was
achie ed o 92.73% o he o e all cases, whils o hei e s his
was achie ed o 83.48% o he o e all cases. Thus, he HG
model p esen ed he e can be conside ed as a easonable way
o p edic he weigh o cows o pu poses o d ug dosing,
bu o o he pu poses whe e mo e accu acy is equi ed (e.g.
selec ion o ca le on LW), he use o a p ope weigh scale is
p e e ed (ILCA/IER 1978; Goe e al. 2001).
3.3. Compa ison o exis ing models o LW p edic ion o
Wes A ican ca le
LW p edic ions om HG measu emen s o ca le in Wes A ica,
om six p io s udies in addi ion o ou s udy, a e shown in
Figu e 3, wi h he eg ession equa ions and coun y and
b eed o animal included (whe e known) o hese p io
s udies gi en in Table 5. The p edic ed weigh om ou s udy
ended be highe in compa ison o ha in o he s udies,
excep a lowe HGs. Resul s o ou s udy we e close o ha
o a p io s udy on Zebu Gob a in Senegal (Chollou e al.
1978), which makes sense gi en ha he majo i y o animals
in ou s udy we e Zebu Gob a o hei c osses. The ela ionship
be ween LW and o he body measu emen s including HG has
been shown o be in luenced by sex, b eed and age (Buldgen
e al. 1984; Sow e al. 1991; Ozkaya & Bozku 2009), p o iding
an explana ion o he di e en models esul ing om he
di e en s udies.
3.4. Fa me s’abili y o es ima e weigh
An addi ional componen o his s udy was o compa e a me s’
es ima e o he weigh o he animal o he measu ed LW. The
co ela ion be ween hese wo a iables was low a 0.53 o he
en i e da ase . As shown in Figu e 4, a me s ended o unde -
es ima e he weigh o hei animals. On a e age, and o cows,
he indigenous Zebu, Zebu by Guze a , Zebu by Bos Tau us and
high Bos Tau us b eed g oups we e unde es ima ed by 115.60
(92.46), 109.10 (83.56), 94.05 (99.47), 149.65(109.18) and 173.81
(118.32) kg, espec i ely (means, and s anda d de ia ions in
Table 4. Li e-weigh p edic ions o cows and hei e s o he di e en b eed g oups, using he o e all eg ession equa ion LW = 4.81 HG–437.52, and o he summa y
in o ma ion in ela ion o his.
B eed g oup
Animal
age g oup N
Li e weigh
p edic ions om
hea -gi h (kg) Mean p edic ed weigh
less mean eal li e weigh
Pe cen age o animals wi h a
p edic ed li e-weigh wi hin he
indica ed pe cen age o hei ue
li e-weigh
Mean SD 20% 10% 5%
Indigenous Zebu Cow 215 300.85 56.43 −1.89 91.16 62.33 35.35
Hei e 55 230.98 73.36 4.90 85.45 63.64 34.55
Indigenous Zebuby Guze a Cow 40 311.16 57.80 0.48 92.50 67.50 37.50
Hei e 18 207.56 66.84 6.66 77.78 55.56 44.44
Indigenous Zebuby Bos Tau us Cow 32 375.83 98.84 −7.36 93.75 68.75 56.25
Hei e 14 254.80 87.14 11.26 64.29 50.00 21.43
High Bos Tau us Cow 16 386.51 95.95 −5.76 100.00 67.25 50.00
Hei e 20 287.35 122.88 8.10 95.00 60.00 35.00
O he Cow 42 319.25 64.64 −7.10 95.24 59.52 35.71
Hei e 7 285.35 72.61 3.64 100.00 85.71 57.14
Figu e 3. Li e weigh p edic ions om hea gi h measu emen s o ca le in Wes
A ica, om di e en s udies.
JOURNAL OF APPLIED ANIMAL RESEARCH 5
b acke s). Only 25.5% o animals had a a me -es ima ed weigh
wi hin 20% o hei ue weigh , and only 7.0% o animals had a
a me -es ima ed weigh wi hin 5% o hei ue weigh . The
unde es ima ion o ca le weigh by a me s ag eed wi h he
indings o Machila e al. (2008) in Kenya, whe e 85.7% o
ca le had hei body weigh s unde es ima ed by hei
Table 5. Model equa ions o p edic ing li e weigh om hea -gi h measu emen s o ca le in Wes A ica, om di e en s udies.
Ca le b eed Ca le age ange (yea s) Ca le sex
a
Coun y Equa ion
b
R
2
Re e ence
Va ious, bu p edominan ly indigenous Zebu 1–18 F Senegal LW = 4.81 HG–437.52 0.85
c
P esen s udy
Zebu Gob a 0.25 –5 M, F Senegal LW = 0.02 HG
2
+ 2.54
HG + 83.32
–Chollou e al. (1978)
Djako e (c oss be ween Zebu Gob a and N’dama) ≤4 F Senegal LW = 3.13 HG–215.32 –Buldgen e al. (1984)
Ndama 1 –2.5 M, F Senegal LW = 3.43 HG–278.83 –Fall e al. (1982)
Zebu Peul and Mau e 0–2 Mali LW = 3.43 HG–278.82 –ILCA/IER (1978)
Zebu Azawak –M, F LW = 0.002 HG
2
+ 1.31
HG–24.12
0.92 Dodo e al. (2001)
Gudali –M, F Nige ia LW = 0.002 HG
2
–4.88
HG–438
–Bu anend an e al. (1980)
a
M = Male; F = Female.
b
LW is li e weigh in kg and HG is hea gi h measu emen in cm.
c
Adjus ed R
2
.
Figu e 4. Sca e plo o a me -es ima ed li e weigh e sus eal li e weigh o he whole da ase (a) and a ious b eed g oups: (b) indigenous Zebu; (c) indigenous Zebu
by Guze a ; (d) indigenous Zebu by Bos Tau us; (e) high Bos Tau us and ( ) o he s.
6S. F. TEBUG ET AL.
owne s. The high unde es ima ion o LW by a me s aises con-
ce ns o widesp ead unde -dosing o ca le wi h e e ina y
d ugs, a majo ou e o d ug esis ance (Dijk e al. 2015),
especially in sub-Saha an A ica whe e animal owne s and
animal heal h p o ide s wi h limi ed aining a e o en espon-
sible o he adminis a ion o d ugs o li es ock (Cheneau e al.
2004).
4. Conclusion
The aim o his s udy was o p o ide a me s wi h a simple and
eliable ool o es ima ing he LW in ca le. The model de el-
oped p edic ed he LW o 91–100% o cow and 64–100% o
hei e ca le wi hin 20% o hei ue LW, dependen on he
b eed g oup, in he weigh ange o abou 100–500 kg. This
model, in he u u e, can be ansla ed in o an easy- o-use
ool such as weigh band o a me s, who only co ec ly es i-
ma ed he LW o abou a qua e o hei animals wi hin 20%
o hei ue LW. Mos models de eloped in di e en egions
in Senegal and Wes A ica unde es ima ed he weigh o
animals in his s udy, which sugges s a need o alida e he
equa ion on u he ca le b eeds, age and sex g oups in
o de o achie e a wide applica ion o he model.
Disclosu e s a emen
No po en ial con lic o in e es was epo ed by he au ho s.
Funding
This wo k was ca ied ou as pa o la ge esea ch p ojec ‘Senegal Dai y
Gene ics’(h p://senegaldai y.wo dp ess.com/), unded by he Finnish Min-
is y o Fo eign A ai s unde he WP2 o he Food A ica P og am. The
au ho s also g a e ully acknowledge unding om he Uni e si y o Helsinki,
Finland. Ou app ecia ion also goes o pa icipa ing a me s o p esen ing
hei animals o his s udy.
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