Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 562 2020
Po a ina s o Slo ak Jou nal o Food Sciences
ol. 14, 2020, p. 562-572
h ps://doi.o g/10.5219/1344
Recei ed: 11 Feb ua y 2020. Accep ed: 23 June 2020.
A ailable online: 28 July 2020 a www.po a ina s o.com
© 2020 Po a ina s o Slo ak Jou nal o Food Sciences, License: CC BY 3.0
ISSN 1337-0960 (online)
EFFECTS OF THE LACTATION PERIOD, BREED AND FEED ON AMINO ACIDS
PROFILE OF MARE’S MILK
Mi osla Fiše a, S anisla K áčma , K ě osla a Šus o á, Pa el T zník, Helena Velicho á,
Lenka Fiše o á, Vlas imil Kubáň
ABSTRACT
The e ec s o he lac a ion pe iod, b eed, and eed on amino acids p o ile o ma e’s milk we e in es iga ed. The eed
con ained wo majo essen ial amino acids (EAAs) leucine (7.31 – 10.3 g.kg-1) and a ginine (6.37 – 9.59 g.kg-1); i also
included mino EAAs me hionine (2.11 – 3.05 g.kg-1) and his idine (2.48 – 3.60 g.kg-1). Glu+Gln, Asp+Asn, and p oline,
majo nonessen ial amino acids (NEAAs), cons i u ed app oxima ely 60% o o al NEAAs (TNEAAs). The a io o o al
EAAs o NEAAs anged om 1:1.2 o 1:1.4. Amino acids (AA) con en h oughou all milk samples a ied due o ma e’s
di e en condi ions and lac a ion days. Excep o he 1P milk sample, o al AA con en in he 2 – 8Ps specimens caused by
di e ences in b eed oscilla ed om he 2nd o 28 h day o lac a ion wi hin he ollowing limi s: 21.9 – 54.6 g.kg-1,
33.6 – 70.7 g.kg-1, 38.1 – 71.2 g.kg-1, 29.46 – 74.2 g.kg-1, 52.2 – 87.1 g.kg-1, 37.9 – 70.3 g.kg-1 and 26.4 – 64.5 g.kg-1,
espec i ely. In ela ion o TEAAs in milk, he highes EAAs le els we e eached in a ginine, leucine and lysine anging
be ween 2.41 – 4.35 g.kg-1, 3.36 – 5.59 g.kg-1 and 2.72 – 4.80 g.kg-1, espec i ely, while he lowes AAs amoun s we e
indica ed in his idine and me hionine, 0.91 – 1.58 g.kg-1 and 1.23 – 2.04 g.kg-1 espec i ely. To al NEAAs con en was
sligh ly highe han ha o EAAs; he TNEAAs o TEAAs a io was 1:0.9 p oxima ely. Glu+Gln, Asp+Asn and p oline
we e de e mined as majo NEAAs o milk anging be ween, 6.77 – 11.0 g.kg-1, 3.21 – 5.60 g.kg-1 and 1.25 – 2.18 g.kg-1,
espec i ely; le els o NEAAs such as cys eine and glycine oscilla ed be ween 0.89 – 1.52 g.kg-1 and 0.64 – 1.15 g.kg-1,
espec i ely. The a e age TAAs con en s caused by b eed di e ences we e 62.8 g.kg-1, 42.8 g.kg-1, 44.7 g.kg-1 and
44.8 g.kg-1, espec i ely, on he 2nd, 5 h, 10 h, and 28 h lac a ion days.
Keywo ds: ma e’s milk; amino acids; mine als; lac a ion; eed; b eed
INTRODUCTION
Milk is a luid sec e ed by he emale o all species o
mammals. The e a e abou 4500 species p oducing milk o
co e he comple e nu i ional equi emen s o he neona e
o he species, as well as o p o ide some immunological
p o ec ion and o sa is y o he physiological equi emen s.
The milk o all species is simila bu he e a e signi ican
species-speci ic di e ences. In e species di e ences in he
quan i a i e composi ion o milk p obably e lec
di e ences in he me abolic p ocesses o he lac a ing
mo he and he nu i i e equi emen s (amino acids,
mine als, a y acid, i amins, e c.) o he sucking young.
In addi ion o supplying all he nu i ional equi emen s o
he neona e, many o he mic o-cons i uen s o milk, such
as oligosaccha ides, immunoglobulins, me al-binding
p o eins, and enzymes se e p o ec i e oles. Because he
nu i ional and physiological equi emen s o each species
a e a he unique, he composi ion o milk shows
subs an ial in e -species di e ences (Fox, 2009; Fox and
Mcsweeney, 1998; Wong e al., 1999).
Milk o only abou 180 species o mammals has been
analyzed up o now; he da a o only abou 50 species a e
conside ed eliable (Fox and Mcsweeney, 1998; Pa k,
2009). Besides being he mos impo an nu i ional
esou ce o oals du ing he i s mon hs o li e, he
ma e´s milk is also one o he mos impo an basic
oods u s o human popula ions in Kazakhs an,
Ki ghizia, Tadzhikis an, Uzbekis an and Mongolia. Lac ic-
alcoholic be e ages called Koumiss, Ai ag and Kumis a e
adi ionally p oduced h ough e men a ion (Di Cagno e
al., 2004; Mon ana i e al., 1996; Malaca ne e al.,
2002; O sko , 1995; Pikul and Wój owski, 2008). To a
lesse ex en , ho ses ha e been used as dai y he ds in
Eas e n and Cen al Eu ope (Bela us, Uk aine, Hunga y,
and Bulga ia) (Ca op ese e al., 2007; Do eau and
Ma in-Rosse , 2002; Fox, 2009). Rega ding Wes e n
Eu ope, whe e he mos impo an p oduc o equine
b eeding is ep esen ed by he oal, s udies on ma e’s milk
ha e concen a ed mainly on he g ow h and heal h o he
newbo n ho se, howe e , in wo decades, he ma e’s milk
has been subjec ed o h ough esea ch and, as he esul ,
consumed o human heal h and as a undamen al ood
(Pa k, 2009). Besides he composi ion o ma e’s milk a ,
he p ope ies o i s p o ein ac ions and composi ion o
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 563 2020
amino acids sugges ha his p oduc is mo e simila o
human milk han o cow’s milk. Fo he abo e eason, and
because o he low c oss- eac i i y be ween cow’s and
ma e’s milk p o eins, a clinical s udy has sugges ed ha
ma e’s milk could be used as a alid eplacemen o
cow’s milk in child en wi h se e e IgE-media ed cow’s
milk p o ein alle gy (Businco e al., 2000). Mo e ecen ly,
he consump ion o milk and o he dai y oods, by i ue
o hei mine al, bioac i e lipids, and p o ein componen s,
has been shown o help educe he isk o ch onic disease
diso de s including os eopo osis, hype ension, excess
body weigh and body a , den al ca ies, and some ypes o
cance (Csapó e al., 1995; Cu adi e al., 2001; Miclo e
al., 2007).
The nu i ional ole o ma e’s milk as a componen o he
die has adi ionally been e alua ed based on i s o e all
con ibu ion o essen ial and non-essen ial nu ien s
o ming a high-quali y die o he suppo o op imal
g ow h and de elopmen o he oal. The colos al pe iod
o ma es is much sho e han ha o cows and he
colos um shows signi ican di e ences om common
milk only on he i s day a e oaling (Ba ello e al.,
2008; Hu h, DiRienzo and Mille , 2006). The nu i ional
dependence o he oal on ma e’s milk composi ion seems
o be mos ma ked immedia ely a e bi h. In he case o
dai y animals, i is well known ha nu ien s diges ed by
he dai y cows ha e a signi ican e ec on he ma e nal
milk composi ion (Hu h, DiRienzo and Mille , 2006).
Fo he p ope nu i ional managemen o ho ses (du ing
he lac a ing pe iod and o oals du ing he sucking
pe iod), i is essen ial o cla i y he ela ionship be ween
he in ake o nu ien s and he milk composi ion in ma es.
The daily nu ien equi emen s o lac a ing ma es a e e y
high, and hey can be compa ed wi h hose o acing
ho ses in hea y aining. Impo an nu ien s a e sec e ed
by he ma e o supply he oal wi h ene gy, p o eins, a s,
ca bohyd a es, i amins, and mine als o op imal
de elopmen and g ow h. To subs i u e hese nu ien
losses and a he same ime o suppo main enance
equi emen s, lac a ing ma es mus consume adequa e
amoun s o quali y eeds (Pagan and Hin z, 1986). I is
known ha he in ake o mine als and amino acids is
pa icula ly impo an o he g ow h o oals. The p o ein
equi emen o he ho se is in luenced by he capaci y o
he p o ein o sa is y he amino acid needs o he animal. In
he ho se die , he e a e cu en ly ou main essen ial
amino acids: lysine, me hionine, h eonine, and
yp ophan. These amino acids a e he mos impo an
nu ien s because limi ing hei le els will a ec he
g ow h and de elopmen o he ho se.
In he las decade, qui e de ailed esea ch on equine milk
and colos um composi ion and, especially s udies on
p o eins, lipids, and mine als ha e been ca ied ou o he
abo e-men ioned easons. Many au ho s ha e epo ed
da a on he p o ile o essen ial nu ien s such as mine als,
amino acids, and i amins in ma e’s milk; howe e , no
complex esea ch including all he abo e ac o s has been
implemen ed (Fiše a e al., 2018). Mo eo e , he e a e
a ew s udies o he ela ionship be ween changes in
ma e’s milk main componen s and he abo e a ec ing
ac o s such as lac a ion s age and o he s.
Scien i ic hypo hesis
The e o e, his s udy is ocused on changes in con en s o
essen ial nu ien s de ec ed in ma e’s milk depending on
lac a ion s ages, eeding sys em, and on some b eeds. The
esea ch aimed o analyze he con en o signi ican
nu i ional componen s in ma e’s milk and lac a ing ma e´s
eed as well as o cha ac e ize he e ec s o se e al ac o s
ha a ec milk p ope ies such as lac a ion pe iods, b eed,
and ma e’s die . Mo e speci ically, he aims o he s udy
we e i) o analyze changes in he majo amino acid
composi ion o ma e’s milk caused by di e ences in
b oodma es and by pe iods in he i s mon h a e
pa u i ion, ii) o analyze he majo amino acid con en and
d y ma e le els in he lac a ing b oodma es´ eed du ing
he lac a ion days a e pa u i ion and iii) o s udy he
ela ions be ween he amino acid composi ion o milk and
eed. The inal goal was o ge de ailed in o ma ion on he
ela ionship be ween amino acids de ec ed in ma e’s milk
and hei eed. E ec s o he lac a ion pe iod, b eed, and
eed on amino acids p o ile o ma e’s milk we e
in es iga ed and successi ely e alua ed.
MATERIAL AND METHODOLOGY
Selec ion o b oodma es and b oodma es’ milk
samples
To collec ma e’s milk and colos um samples, eigh
di e en ma u e, well-de eloped, and no mal b oodma es
we e selec ed. All he selec ed ma es we e om se en o
six een yea s o age (10 ±3 pa i ies), wi h he li e weigh
be ween 500 and 600 kg. They we e kep indoo and
ou doo indi idually and ed wi h 1.3 kg whea b an, 2.1
kg hominly, 5.0 kg oa s e e y day. Wa e was a ailable
om oughs a all imes. All ma es we e accina ed
agains in luenza and he pes i us pe 6 mon hs.
The milk samples (app oxima ely 40 – 50 mL) om
selec ed b oodma es we e aken in o plas ic con aine s on
2, 5, 10, 28, and 56 days pos pa um; 31 indi idual
samples we e collec ed in o al (Table 1). Be o e milking,
oals we e sepa a ed om hei mo he s o app oxima ely
2 hou s o p e en suckling. The i s milking o ma es was
ca ied ou wi h hands as deep as possible. Some ma es
had no p e iously been subjec ed o any milking
p ocedu es. The second milking was done acco dingly.
Collec ed milk samples we e aken di ec ly o he
labo a o y and hen immedia ely s o ed and ozen a -20
°C and -25 °C. The samples o eed mix u e o he
lac a ing ma es (in he amoun o app oxima ely 500 g)
we e collec ed in o polye hylene bags on he days o milk
sample collec ing al oge he 29 samples we e collec ed
(Table 1). Then all he samples we e aken o he
labo a o y and s o ed a oom empe a u e.
All he collec ed milk samples we e being ozen in
a eeze a -80 °C o 4 hou s, and hen hey we e being
lyophilized a 120 Pa and -50 °C o 2 days using acuum
lyophiliza ion (Labicom, Czech Republic). All he
lyophilized samples we e s o ed in a idge a -4 °C be o e
hei analysis. All he eed samples we e being mixed o
g ound using a mixe o 3 min and hen pu in o plas ic
con aine s. All he g ounded samples we e s o ed a oom
empe a u e p be o ehei analysis.
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 564 2020
Reagen s and solu ions: All eagen s used we e o
analy ical eagen g ade (Sigma-Ald ich, S . Lois, Mo,
USA). Concen a ed hyd ochlo ic acid 37% ( / ) HCl,
6 mol.L-1 HCl, a gon gas, 0.1 mol.L-1 HCl, loading bu e
o pH 2.2, 30% ( / ) H2O2, 85% ( / ) HCOOH.
Equipmen : The con en s o amino acids in all samples
we e de e mined by using an AAA 400 Amino Acid
Analyze (INGOS, P ague, Czech Republic), a liquid
ch oma og aph designed o he analysis o amino acids on
an ion-exchange column wi h pos -column de i a iza ion
by means o ninhyd in and o he de e mina ion o
biogenic amines. A he moblock (Labicom, Olomouc,
Czech Republic), a o a y e apo a o (Heidolph
Ins umen s GmbH + Co. KG, Kelheim, Ge many) and an
oil ba h (Memme GmbH + Co. KG, Schwabach,
Ge many) we e used o acid and alkaline oxidizing
hyd olyses o all milk and eed samples.
P ocedu es
Analysis o d y ma e
D y ma e (DM) was de e mined acco ding o he
AOAC s anda d p ocedu e (AOAC, 1990). Con en s o
d y ma e we e calcula ed acco ding o he ollowing
equa ion DM (%) = m2.100/m1, whe e DM (%) is he
pe cen age o a o al d y ma e , m1 is sample weigh
be o e DM de e mina ion and m2 is sample weigh a e
d ying.
Analysis o amino acid con en s
The con en s o amino acids in all samples we e
de e mined by using an AAA 400 amino acid analyze
(INGOS, P ague, Czech Republic). An amino acid
analyze is a special compac liquid ch oma og aph
designed o he analysis o amino acids on an ion-
exchange column wi h pos -column de i a iza ion by
means o ninhyd in and o he de e mina ion o biogenic
amines.
The acidic hyd olyses o all milk and eed samples we e
pe o med wi h ew modi ica ions unde hyd olysis ime
and empe a u e condi ions acco ding o Buňka e al.
(2009) and Buňka, H abě and K áčma (2004). B ie ly,
he lyophilized milk (50 – 60 mg) and d ied eed samples
(80 – 90 mg) we e accu a ely weighed in sc ew-capped
es ubes o acidic hyd olysis (capaci y o 20 mL) wi h
Te lon caps. 15 mL HCl (6 mol.L-1) solu ions we e added
o e e y ube wi h a sample. A e wa d, he ubes we e
being pu ged by blowing wi h a gon gas o app oxima ely
20 seconds, and hen he acuum-sealed ubes we e being
hea ed in a he moblock a 117 ±1 °C o 23 hou s. The
empe a u e o he he moblock was independen ly
con olled by using a he mome e imme sed in a es ube
illed wi h silicone oil ( he es ube was placed in he
he moblock). A e hyd olysis, hyd olyzed samples we e
il e ed using a pape il e and washed wi h 0.1M HCl.
Then he il a es we e i s ly d ied using a o a y
e apo a o a 50 °C and 90 pm and e apo a ed secondly
and hi dly a e a double washing wi h dis illed wa e
(app oxima ely 25 mL) un il we ob ained a d ied mass.
The d ied mass was dissol ed in loading bu e wi h pH
2.2 and made up o he ma k in a 25 mL olume ic lask.
Then 1.5 mL o his solu ion was pu in o a plas ic
con aine and il e ed h ough a 0.45 µm il e and
subsequen ly placed in a idge un il loaded o he amino
acid analyze . All analyses we e pe o med in iplica e o
e e y sample.
In o de o de e mine sulphu -con aining amino acids, all
samples we e hyd olyzed sepa a ely wi h HCl (6 mol.L-1)
a e oxidizing he samples wi h pe o mic acid acco ding
o me hods elabo a ed by Buňka, H abě and K áčma
(2004) and Ama akoon (2009) wi h ew modi ica ions.
Pe o mic acid was p epa ed in he a io o 1:9 om 30%
H2O2 and 85% HCOOH. A e incuba ion a oom
empe a u e o 2 hou s, he pe o mic acid was being kep
in a idge a 4 ±1 °C o app oxima ely 30 seconds. The
lyophilized milk (50 – 80 mg) and d ied eed samples
1000 – 8000 mg) we e accu a ely weighed and pu in o
a 250 mL E lenmeye lask. 15 mL o pe o mic acid was
added o each sample and hen i was being cooled a
4 ±1 °C a leas o 16 hou s o sample oxidizing. A e
oxida ion, 1 – 2 mL o concen a ed HCl was added o he
oxidized samples and incuba ed in he hood o
app oxima ely 30 min un il chlo ine gas was emo ed.
Then 150 mL o 6 mol.L-1 HCl was added o he oxidized
samples and hea ed in an oil ba h a 117 ±1 °C o 23
hou s. A e hyd olysis, he samples we e il e ed wi h a
pape il e , dissol ed in 0.1 mol.L-1 HCl and made up o
he 250 mL ma k in a olume ic lask. 25 mL o he
dilu ed sample was ans e ed wi h a 25 mL pipe e in o a
lask and hen he hyd ochlo ic acid was e apo a ed in he
o a y e apo a o a e washing i wice wi h dis illed
wa e un il a d ied mass was ob ained. Then he d ied mass
was dissol ed in loading bu e wi h pH-2.2 and made up
o he ma k in a 25 mL olume ic lask. Then 1.5 mL o
his solu ion was pu in o a plas ic con aine a e il e ing
h ough a 0.45 µm il e and hen placed in a idge be o e
loading i o he amino acid analyze . All analyses we e
pe o med in iplica e o e e y sample.
De e mina ion o amino acids
A s anda d mix u e o 17 analyzed amino acids (aspa ic
acid + aspa agine, h eonine, se ine, glu amic acid +
glu amine, p oline, glycine, alanine, aline, isoleucine,
leucine, phenylalanine, y osine, his idine, lysine, a ginine,
me hionine, and cys ine) was ob ained om INGOS
(P ague, Czech Republic). The con en o amino acids was
de e mined by an AAA 400 de ice acco ding o he
manu ac u e ´s p og am. Then he column was being
egene a ed wi h 0.2 mol.L-1 NaOH o 10 min and
s abilized o u he 17 min wi h bu e A. The
empe a u e o he column was se o 60 °C o a speci ic
ime slo (0 – 60 min and 90 – 102 min) and o 74 °C in
he mean ime (60 – 90 min). The ollowing low a es
we e employed: 0.3 mL.min-1 o bu e s and 0.2 mL.min-1
o ninhyd in eagen . Each hyd olysa e was analyzed in
duplica e.
S a is ical analysis
All he con en s o o al amino acids in all he analyzed
samples we e exp essed as mean ±SD and calcula ed based
on e en ion ime ob ained in ch oma og ams (Buňka,
H abě and K áčma , 2004; Ingos L d., 2006). The da a
we e e alua ed by summa y s a is ics and he a iance was
calcula ed using an ANOVA p ocedu e pe o med using
S a is ica® 12.0 so wa e (S a So , USA). All da a
ob ained by he AAA 400 we e exp essed as he mean
le els in esh milk using he ollowing equa ion
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 565 2020
TA = A0.ε0 = (L-C)/(D-C), whe e TA is amino acid
con en in esh milk, A0 is amino acid con en o
lyophilized milk, ε0 is co ela ion coe icien , L is esh
milk weigh , D is lyophilized milk weigh and C is
con aine weigh .
RESULTS AND DISCUSSION
D y ma e in he eed
The d y ma e (DM) con en in all eed samples o he
lac a ing ma es is shown in Table 2. The pe cen age o
DM con en a ied sligh ly in indi idual eed samples due
o p epa a ion condi ions o eed mix u e and because o
he a io o o ages in he eed mix u e. The a e age DM
con en oscilla ed be ween 88.6% and 90.6%. Acco ding o
some esea che s (Loope e al., 2001), he DM con en in
selec ed high-quali y eed ypes o he lac a ing ma es
such as g ains, hay, and cha anged om 87 o 91 %
(w/w). The abo e esul s comply wi h NRC (Pagan and
Hin z, 1986). DM con en in all he eeds, he e o e, is in
acco dance wi h he s anda d le el o DM in eed and
o age o he lac a ing ma e.
Amino acid composi ion o eed and milk
The amino acid con en in he eed
In he expe imen , he essen ial amino acids and non-
essen ial amino acid p o iles o each in es iga ed eed o
he lac a ing ma e we e de e mined. All he da a a e
exp essed as mean ±SD in g.kg-1 (p <0.005) and hey also
depic conside able a ia ions in he amino acid con en in
eeds. The p o ein nu i i e alue is gi en by i s amino
acid p o ile. The p o ein con en s in ho se eeds such as in
g ains, hay, cha , pas u e, o in o he s ange om 10 o
25% o o al weigh depending on he ype o eeds (Pagan
and Hin z, 1986). Ou o 20 amino acids, a human being
o an animal can syn hesize only nine. The emaining
amino acids should be p o ided in hei ood. A ginine is
ega ded as a semi-essen ial amino acid (Boisen,
H elplund and Weisbje g, 2000).
As shown in ables, AA con en s in eeds o he lac a ing
ma es di e ed, which could ha e been caused by some o
he abo e men ioned ac o s. Gene ally, NEAA glu amic
acid (Glu+Gln) con en (18 – 21 g.kg-1) eached he
highes alues while he EAA me hionine and his idine
le els
(2.5 – 3.6 g.kg-1) d opped he lowes among all eeds. EAA
a ginine and leucine, NEAA aspa ic acid (Asp+Asn) and
p oline con en in all eeds we e highe han le els o o he
AAs, 7 – 9 g.kg-1, 8 – 10 g.kg-1, 7 – 9 g.kg-1 and 8 – 9 g.kg-
1 espec i ely. In he animal die , he e a e cu en ly
ecognized ou main essen ial amino acids: lysine,
me hionine, h eonine, and yp ophan, which a e he mos
impo an nu ien s; limi ing hei le els will a ec he
g ow h and de elopmen o he ho se (Saas amoinen and
Koskinen, 1993). Pa icula ly in he ho se, he daily lysine
equi emen o he lac a ing ma e anges be ween
13.8 – 16.9 g pe 100 kg o body weigh (Na ional
Resea ch Council. 2007). The con en s o hese abo e
AAs in eeds we e, excep o yp ophan, which was no
analyzed, ela i ely lowe han he amoun s o he o he s.
Lysine le els anged be ween 3.0 – 4.5 g.kg-1, me hionine
amoun s oscilla ed be ween 2.5 – 3.6 g.kg-1 and h eonine
con en anged be ween 3.4 – 4.0 g.kg-1.
Rega ding o he AA such as EAA isoleucine, aline and
phenylalanine, NEAA cys eine, glycine, se ine and
y osine, hei le els did no di e much anging be ween
3.4 g.kg-1, 4.8 – 6.2 g.kg-1, 4.7 – 6.0 g.kg-1, 3.4 – 3.8 g.kg-1,
5 – 6 g.kg-1, 4.5 – 5.2 g.kg-1 and 3.4 – 7.0 g.kg-1,
espec i ely. Acco ding o some epo s, y osine and
cys eine a e ega ded as semi-essen ial amino acids, since
hey can be syn hesized exclusi ely om me hionine and
phenylalanine, espec i ely (Boisen, H elplund and
Weisbje g, 2000). To al NEAA amoun s (app oxima ely
50 – 66 g.kg-1) in all eeds on all days we e sligh ly highe
han o al EAA le els (app oxima ely 40 – 51 g.kg-1). The
highes o al EAA con en eached a maximum (51.7 g.kg-1
in 5F) on he 2nd day while he lowes alue was ound in
1F on he 2nd day (40.5 g.kg-1). In he case o NEAA, he
highes amoun inc eased o 66.8 g.kg-1 in 7F on he 2nd
day and he lowes le el was 50.4 g.kg-1 in 2F on he 5 h
day. The abo e amoun s we e compa able o le els ound
in some ypes o eeds such as oa s, ba ley, so ghum and
whea (Awadalka eem, Mus a a and El Tinay, 2008;
Pagan and Hin z, 1986). The p o ein equi emen o he
ho se is in luenced by how well he p o ein p o ides o
he amino acid needs o he animal; some EAAs a e
limi ing essen ial amino acids in g ass-based eeding
p og ams. I has been epo ed ha daily p o ein in ake o
he lac a ing ma e a e ages a 1493 g.day-1 (Pagan and
Hin z, 1986). Le els o TAAs in examined eeds anged
be ween 92 – 116 g.kg-1; hei amoun was highe han ha
in some species o oa s and he e was an ag eemen wi h
hei amoun con ained in good quali y eed o animals
(Biel, Bobko and Macio owski, 2009).
A e age amino acid composi ion o eed
The a e age con en o all AAs examined in 1F – 8F on
di e en lac a ion days is summa ized in Table 3. The
a e age con en o each amino acid was calcula ed in
ela ion o amoun s o he AA e ealed in all eed on he
2nd, 5 h 10 h and 28 h, days espec i ely. As shown in his
able, all AA con en s, excep o EAA leucine and
me hionine and o NEAA p oline, on he 28 h day and in
eeds on he 5 h and 28 h days sligh ly dec eased. I was
obse ed ha he AA con en s in eeds eached he highes
le els on he 2nd day while he lowes amoun s we e
de ec ed in eeds on he 5 h day. Ne e heless, EAA
phenylalanine con en on he 10 h day was highe han he
amoun o he o he s. The con en s o a ginine and leucine,
he majo EAAs in eed, g ew highes anging be ween
7.70 – 8.42 g.kg-1 and 8.66 – 9.35 g.kg-1, espec i ely.
O he EAA con en s we e wo and h ee imes lowe
when compa ed o majo EAA amoun s. Mo eo e ,
Glu+Gln, p oline, alanine and Asp+Asn domina ed among
he NEAA in eeds anging be ween 18.5 – 19.9 g.kg-1,
7.31 – 8.30 g.kg-1, 6.22 – 6.52 g.kg-1 and 7.90 – 8.36 g.kg-
1, espec i ely. Con en s o he o he AA did no di e
mu ually; me hionine and his idine le els in eed sco ed
lowes . The e o e, he o al EAA con en in all eeds was
1.2 imes lowe han NEAA con en ; he a e age a io o
EAA o NEAA was 1:1.2 (44.1 – 47.0 g.kg-1:
56.4 – 61.2 g.kg-1). I was p o ed ha all eeds o he
lac a ing b oodma es we e ich in EAA.
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 566 2020
Table 1 Milk and eed sample cha ac e is ics.
Milk
Days pos pa um
Feed
Days pos pa um
2nd
5 h
10 h
28 h
56 h
2nd
5 h
10 h
28 h
56 h
1P
+
+
+
+
-
1F
+
+
+
+
+
2P
+
+
+
+
+
2F
+
+
+
+
-
3P
+
+
+
+
-
3F
+
+
+
+
-
4P
+
+
+
+
-
4F
+
+
+
+
-
5P
+
+
+
+
-
5F
+
+
+
-
-
6P
+
+
+
-
-
6F
+
+
+
-
-
7P
+
+
+
-
-
7F
+
+
+
-
-
8P
+
+
+
+
-
8F
+
+
+
-
-
No e: + sample was aken; - sample was no aken.
Table 2 The d y ma e con en o eed (%, w/w).
Feed
D y ma e (mean alue ±SD)
2nd
5 h
10 h
28 h
56 h
1F
89.38 ±0.19
89.32 ±0.15
89.04 ±0.51
88.96 ±0.66
89.49 ±0.51
2F
90.56 ±0.67
88.64 ±0.34
89.54 ±0.37
89.36 ±0.55
n.a.
3F
90.32 ±0.54
89.55 ±0.86
88.69 ±0.98
89.04 ±0.22
n.a.
4F
88.89 ±0.42
89.14 ±0.51
89.06 ±0.20
88.90 ±0.08
n.a.
5F
89.64 ±0.40
88.99 ±0.70
88.65 ±0.68
n.a.
n.a.
6F
90.12 ±0.39
88.80 ±0.57
88.81 ±0.58
n.a.
n.a.
7F
90.47 ±0.31
89.37 ±0.37
88.81 ±0.53
n.a.
n.a.
8F
90.00 ±0.63
88.80 ±0.39
88.7 ± .51
n.a.
n.a.
No e: F – eed samples, SD – s anda d de ia ion, n.a. – no analyzed.
Table 3 The a e age con en o each amino acid in 1F – 8F samples eed.
Amino acid (g.kg-1)
1F – 8F
2nd day
5 h day
10 h day
28 h day
mean
SD
mean
SD
mean
SD
mean
SD
A ginine
8.42
0.82
7.91
0.89
8.18
0.84
7.70
0.74
His idine
3.15
0.32
2.83
0.29
2.95
0.30
2.88
0.29
Isoleucine
4.09
0.36
3.91
0.38
4.04
0.40
3.91
0.27
Leucine
9.35
0.77
8.66
0.80
8.98
0.90
8.99
0.71
Lysine
4.31
0.42
4.00
0.50
4.18
0.47
3.77
0.35
Me hionine
2.49
0.26
2.32
0.09
2.38
0.09
2.38
0.21
Phenylalanine
5.45
0.51
5.32
0.60
5.49
0.62
5.32
0.47
Th eonine
3.89
0.32
3.63
0.41
3.77
0.38
3.69
0.35
Valine
5.87
0.55
5.55
0.56
5.73
0.61
5.57
0.46
TEAA
47.02
4.34
44.13
4.51
45.70
4.61
44.21
3.85
Alanine
6.52
0.52
5.99
0.60
6.22
0.59
6.16
0.56
Asp+Asn
8.36
0.71
7.90
0.81
8.13
0.81
7.91
0.61
Cys eine
3.57
0.13
3.52
0.13
3.52
0.22
3.46
0.18
Glu+Gln
19.94
1.45
18.45
1.66
19.23
1.69
18.75
1.54
Glycine
5.69
0.50
5.26
0.57
5.48
0.53
5.29
0.52
P oline
8.30
0.56
7.31
0.44
7.67
0.33
7.79
0.53
Se ine
4.89
0.36
4.55
0.48
4.72
0.45
4.61
0.42
Ty osine
3.96
1.31
3.37
0.43
3.47
0.40
3.40
0.44
TNEAA
61.24
5.54
56.35
5.12
58.45
5.03
57.36
4.79
TAA
108.26
9.88
100.48
9.63
104.16
9.65
101.57
8.63
No e: TEAA – o al essen ial amino acid con en , TNEAA – o al non-essen ial amino acid con en , TAA – o al amino acid con en .

Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 567 2020
The a io o AA in some eeds o animals such as in oa s
g ain was epo ed as 1:2.8 (27 g. (16 g N)-1:
75 g.(16 g N)-1) (Biel, Bobko and Macio owski, 2009).
TAA le els in eeds anged om 100.48 g.kg-1 o
108.26 g.kg-1 depending on eeding days. O e all, hese
AA concen a ions in all eeds we e conside ably highe
han hose in daily eed in ake o lac a ing ma es (Pagan
and Hin z, 1986).
The amino acid con en in milk
The a ia ions in he amino acid con en s in milk samples
om he eigh lac a ing ma es on se e al days a e
pa u i ion a e shown in Table 4, as a ep esen a i e
example. As shown in his able, he AA con en s in 1P on
all days we e h ee imes lowe han hose in o he ma es
while he e we e signi ican di e ences in AA con en s in
all milk. I was, pe haps, due o sample p ocessing and he
ma e’s physiological condi ions. I was obse ed ha he
highes AA con en s we e eached in all milk on he
2nd day o lac a ion; a e wa ds, all AA con en s d opped
conside ably on he 5 h day. I co esponded o he end o
he colos al pe iod.
In many pape s, he lac a ion pe iod is he mos
signi ican ac o in luencing he composi ion o all
mammalian milk, in pa icula o ho se milk; p o ein
con en in colos al pe iod is i e imes highe han ha in
milk pe iod, due o p o iding he oal wi h all nu ien s
and immune subs ances du ing he i s ew days
(K áčma e al., 2005). The colos al pe iod o ma es was
ound o be signi ican ly sho e han ha o cows; quali y
o colos um showed signi ican di e ences om ha o
no mal milk only on he i s 2 days a e oaling
(Salamon e al., 2009). The AA con en s in 2P, 3P, 4P,
and 8P on he 10 h day o lac a ion was inc eased
signi ican ly and hen dec eased g adually. In ega d o 1P,
5P, 6P and 7P, he AA con en was con inuously
dec easing ill he 10 h day o lac a ion, al hough on he
28 h day i inc eased sligh ly again. These changes ag eed
wi h epo s on ma e’s milk composi ion du ing he
lac a ion pe iod.
Some au ho s epo ed ha a e pa u i ion, he AA
con en in ma e’s milk was dec easing con inuously
(Csapó e al., 2009). Leucine, lysine, a ginine and aline
con en s in all ma es’ milk samples we e highe han hose
o o he EAAs, anging wi hin 4.4 – 6.7 g.kg-1,
3.7 – 6.5 g.kg-1, 4.2 – 5.8 g.kg-1 and 2.7 – 4.9 g.kg-1,
espec i ely; he leucine con en was he highes one while
his idine con en (1.2 – 2.2 g.kg-1) was he lowes one in all
milk samples. In he case o NEAA, Glu+Gln, P oline and
Asp+Asn, hei con en s in milk anged be ween 8.8 –
15.8 g.kg-1 and 4.7 – 7.6 g.kg-1 espec i ely; hey eached
he highes le els while glycine and alanine con en s
oscilla ing be ween 0.9 – 1.5 g.kg-1 and 1.3 – 1.9 g.kg-1,
d opped lowes in all milk samples. The abo e AA
con en s p o ile ag eed wi h ha oundby Ma sui, Inoue
and Asai (2003).
Some au ho s epo ed ha when he AA composi ion
was exp essed as AA g.100g-1 p o ein, he changes we e
no iceably less appa en ; i was due o high amoun o ee
AA in milk du ing he colos al pe iod; a e he colos al
pe iod, o al ee AA concen a ion dec eased o hal alue
om 0.6 g.kg-1 o 0.3 g.kg-1. The con en s o ee AAs in
colos um, excep o h eonine, se ine, and glu amic acid
le els, we e abou wice as high as hose in no mal milk
(Csapó-Kiss e al., 1995). O e all, AA con en s in 6P on
lac a ion days we e highe han hose in he o he s;
oscilla ions in 3P, 4P, 5P, 7P, and 8P AA du ing lac a ion
days we e compa able o each o he and no signi ican
di e ence was obse ed. Al hough he AA amoun s in all
milk on di e en lac a ion days di e ed om each o he ,
hey a e sugges ed o depend on eed and b eed
di e ences.
A e age amino acid composi ion o milk
Fu he , Table 5 shows he a e age o al AA con en in
milk ela ed o di e ences be ween eigh b oodma es,
which we e ed wi h abo e men ioned good quali y eeds
du ing lac a ion, ela i e o 2nd, 5 h 10 h and 28 h days o
lac a ion. I means ha he con en o each amino acid
dec eased, wi hou any excep ion, conside ing he change
o colos um o milk (2nd o 28 h day), al hough, on he 10 h
day, a sligh inc ease o all AA con en s in milk was
obse ed in milk.
Gene ally, a e he 2nd and 5 h day o lac a ion, he e was
a sligh di e ence in AA con en which ag ees wi h he
da a epo ed by some au ho s who sugges ed no changes
in he amino acid composi ion o ma e’s milk p o eins
be ween he 8 h and 45 h day o lac a ion (Csapó-Kiss e
al., 1995; Da is e al., 1994). In he die o he ho se and
he newbo n oal, lysine, me hionine, h eonine, and
yp ophan a e conside ed he mos impo an subs ances
o a ec i s g ow h and de elopmen (Saas amoinen and
Koskinen, 1993). Lysine was de ec ed o be one o he
majo EAAs in milk while me hionine and h eonine
con en we e he lowes ones. The con en o majo EAAs
a ginine, leucine, lysine, isoleucine and aline on he 2nd
day o lac a ion ollow: 4.35 g.kg-1, 5.59 g.kg-1,
4.80 g.kg-1, 3.01 g.kg-1 and 3.49 g.kg-1, espec i ely. On
he 28 h day o lac a ion, hei le els dec eased o 2.41
g.kg-1, 3.36 g.kg-1, 2.72 g.kg-1, 1.79 g.kg-1 and 2.10 g.kg-1,
espec i ely.
Rega ding he oscilla ion o NEAA amoun s, he pa e n
simila o ha o EAAs was obse ed; he majo NEAA
Glu+Gln le els dec eased om 11.0 g.kg-1 o 6.7 g.kg-1
and Asp+Asn con en d opped om 5.6 g.kg-1 o
3.21 g.kg-1, e c. The dec ease o AA con en in milk
be ween he 2nd and he 28 h day anged be ween 30 % and
40 %; i was compa able o a dec ease o AA con en
s udied by Csapó e al. (2009). To al EAA con en
eached 30.3 g.kg-1, 20.5 g.kg-1, 21.2 g.kg-1 and 17.7 g.kg-1
on he 2nd, 5 h, 10 h, and 28 h days espec i ely, showing
alues lowe han o al le els o NEAA.
The e o e, he a e age a io o o al EAA o o al NEAA
con en on lac a ion days was calcula ed as 1:1.1, which is
in disag eemen wi h he 1:2.2 alue ound by Csapó e al.
(2009); mo eo e , he a io in colos um was epo ed as
1:2 (Leh ola and Saas amoinen, 2010), which was
in luenced by b eeds and hei eed. On he o he hand,
o al EAA con en was signi ican ly highe , and he o al
NEAA was lowe han he alues men ioned in he
li e a u e. To al AA con en s du ing lac a ion days eached
62.8 g.kg-1, 42.8 g.kg-1, 44.7 g.kg-1 and 37.1 g.kg-1
espec i ely; hey dec eased h oughou lac a ion days
analogically o hose o EAAs and NEAAs.
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 568 2020
Table 4 Amino acid con en in 1P sample milk.
Amino acid (g.kg-1)
1P
2nd day
5 h day
10 h day
28 h day
2 – 28 h days
Mean
SD
mean
SD
mean
SD
mean
SD
mean
SD
A ginine
1.28
0.05
0.82
0.02
0.77
0.04
1.02
0.01
0.97
0.23
His idine
0.50
0.01
0.40
0.01
0.29
0.02
0.39
0.01
0.39
0.09
Isoleucine
0.99
0.02
0.76
0.03
0.58
0.03
0.73
0.04
0.77
0.17
Leucine
1.92
0.06
1.47
0.03
1.14
0.08
1.47
0.12
1.50
0.32
Lysine
1.51
0.00
1.18
0.05
0.87
0.05
1.05
0.04
1.16
0.27
Me hionine
0.72
0.02
0.54
0.03
0.41
0.04
0.48
0.02
0.54
0.13
Phenylalanine
0.89
0.05
0.64
0.07
0.50
0.05
0.70
0.06
0.68
0.16
Th eonine
0.75
0.02
0.66
0.01
0.46
0.03
0.62
0.03
0.62
0.12
Valine
1.17
0.06
0.93
0.05
0.74
0.09
0.90
0.02
0.93
0.18
TEAA
9.74
0.28
7.40
0.32
5.76
0.43
7.37
0.35
7.57
1.67
Alanine
0.74
0.02
0.52
0.01
0.40
0.02
0.56
0.04
0.55
0.14
Asp+Asn
1.84
0.06
1.45
0.09
1.00
0.07
1.37
0.05
1.42
0.34
Cys eine
0.54
0.05
0.41
0.02
0.32
0.02
0.38
0.01
0.41
0.09
Glu+Gln
3.49
0.09
3.01
0.08
2.28
0.12
3.23
0.29
3.00
0.52
Glycine
0.40
0.01
0.29
0.03
0.21
0.01
0.29
0.01
0.30
0.08
P oline
1.60
0.02
1.41
0.10
1.05
0.11
1.43
0.01
1.37
0.23
Se ine
1.06
0.06
0.88
0.02
0.63
0.05
0.88
0.05
0.86
0.18
Ty osine
1.01
0.01
0.70
0.02
0.53
0.02
0.74
0.09
0.75
0.20
TNEAA
10.69
0.32
8.68
0.38
6.42
0.41
8.88
0.56
8.67
1.78
TAA
20.42
0.59
16.08
0.70
12.18
0.84
16.25
0.91
16.23
3.45
No e: TEAA – To al essen ial amino acid; TNEAA – To al non-essen ial amino acid; TAA – To al amino acid. In i alic
– A e age con en o each amino acid a o al lac a ion days.
Table 5 A e age con en o each amino acid in 1P – 8P samples milk.
Amino acid (g.kg-1)
1P – 8P
2nd day
5 h day
10 h day
28 h day
mean
SD
mean
SD
mean
SD
mean
SD
A ginine
4.35
1.35
2.72
0.95
2.91
1.21
2.41
1.12
His idine
1.58
0.51
1.06
0.33
1.08
0.47
0.91
0.44
Isoleucine
3.01
0.97
2.09
0.66
2.17
0.89
1.79
0.83
Leucine
5.59
1.81
3.87
1.19
4.05
1.64
3.36
1.51
Lysine
4.80
1.55
3.20
1.03
3.27
1.34
2.72
1.33
Me hionine
2.04
0.64
1.59
0.50
1.43
0.66
1.23
0.55
Phenylalanine
2.82
0.92
1.87
0.63
1.97
0.83
1.63
0.77
Th eonine
2.59
0.85
1.75
0.56
1.74
0.69
1.49
0.71
Valine
3.49
1.13
2.37
0.76
2.57
1.06
2.10
0.94
TEAA
30.28
9.75
20.51
6.60
21.19
8.78
17.65
8.18
Alanine
2.18
0.68
1.40
0.47
1.47
0.59
1.25
0.56
Asp+Asn
5.60
1.75
3.76
1.17
3.87
1.61
3.21
1.46
Cys eine
1.52
0.47
1.18
0.38
1.03
0.41
0.89
0.39
Glu+Gln
11.00
3.65
7.64
2.37
8.18
3.24
6.77
2.93
Glycine
1.15
0.35
0.75
0.24
0.76
0.31
0.64
0.30
P oline
4.99
1.64
3.54
1.03
3.92
1.63
3.17
1.28
Se ine
3.30
1.03
2.24
0.69
2.33
0.93
1.95
0.87
Ty osine
2.76
0.83
1.81
0.58
1.92
0.80
1.58
0.73
TNEAA
32.51
10.39
22.33
6.93
23.47
9.53
19.46
8.50
TAA
62.79
20.14
42.84
13.53
44.67
18.30
37.11
16.68
No e: TEAA – To al essen ial amino acid; TNEAA – To al non-essen ial amino acid; TAA – To al amino acid.
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 569 2020
Some au ho s epo ed o al AA concen a ion in ma e’s
colos um o each i s peak in he i s 24 hou s a e
pa u i ion; i anged om 160 o 170 g.kg-1 d opping hen
o 40 – 42 g.kg-1 on he 2 – 5 h days, while i dec eased o
i s minimum alue o 20 – 25 g.kg-1 on 8 – 45 h days o
lac a ion (Csapó-Kiss e al., 1995). Equine, milk on he
1s and 2nd day pos pa um is conside ed as ini ial milk
which shows bo h colos um and milk p ope ies;
he e o e, he TAA con en s on he 2nd and 5 h lac a ion
days did no a y signi ican ly. Ne e heless, TAA le els
on he 10 h and 28 h days we e conside ably highe han he
con en s epo ed abo e. I has been ound by se e al
au ho s ha he e we e no signi ican di e ences in he
amino acid composi ion be ween he b eeds bu ha o al
AA con en depends on he eeding sys em and b eeds
(Pagan and Hin z, 1986; an den Be g, 2009).
The ela ion be ween amino acid le els in milk and eed
Supplemen a y eed and nu i ion a e conside ed one o
he mos impo an ac o s ha play a c ucial ole in
enhancing he p oduc ion o milk and i s composi ion.
Based on he con en s o AA in all eeds and milk, which
a e gi en in Table 3 and Table 5, he ela ions be ween
a e age con en s o each AA in he milk o eigh
b oodma es and s udied eeds o he lac a ing ma es on
he 2nd, 5 h, 10 h and 28 h days o lac a ion a e summa ized
in Figu e 1, Figu e 2 and Figu e 3.
Signi ican ela ionships be ween all he compa ed da a
we e obse ed; i was indica ed ha he de ia ions in
le els o each amino acid in milk co ela ed mu ually wi h
hose ound in eeds on all days o lac a ion, wi h he
excep ion o he 2nd day. All amino acid con en s on he 2nd
day o lac a ion we e conside ably highe han AA le els
on o he days; he abo e was due o he end o he colos al
pe iod (Csapó e al., 2009). Pa icula ly in EAA a ginine,
isoleucine, leucine, lysine, and phenylalanine, in NEAA
Asp+Asn, Glu+Gln, p oline and se ine, he abo e
endency was p onounced signi ican ly.
F om he 5 h o 28 h lac a ion days, all amino acid
con en s in milk sligh ly dec eased. I was epo ed ha
o al AA con en on he 8 – 45 h days was wice lowe han
ha on he 5 h lac a ion day (Csapó-Kiss e al., 1995). In
con as , his s udy demons a ed ha on he 10 h lac a ion
day all he AA concen a ions, excep o EAA lysine,
me hionine, h eonine and o NEAA glycine, inc eased
sligh ly while all amino acid concen a ions in eeds
inc eased.
Me hionine, lysine and phenylalanine a e he mos
limi ing c ucial amino acids con ained in animal eed;
some eeds sligh ly imp o e hei amoun in milk (Abu-
Ghazaleh, Schingoe he and Hippen, 2001). Wi h he
excep ion o me hionine, hese AA con en s we e ound o
be adequa e o he lac a ing ma es in all he eeds.
Rega ding eeds du ing all lac a ion days, AA con en s in
eed we e ound o be in an adequa e amoun o co e
daily in ake o he lac a ing ma e. As epo ed in he
li e a u e, by inc easing he le el o ene gy in eed and o
he p opo ion o p o ein concen a e in he die , ma e’s
milk amoun inc eased, bu milk p o ein con en dec eased
by 4 g.L-1. Mo eo e , he p o ein supplemen a ion in he
die showed inconsis en e ec s on milk p o ein con en .
Addi ionally, as esea che s used a supplemen o p o ein
concen a e in a hay-based die , milk p o ein con en
Figu e 1 Rela ion be ween a e age o al con en o
essen ial amino acids in milk and eed.
Figu e 2 Rela ion be ween a e age o al con en o non-
essen ial amino acids con en in milk and eed.
Figu e 3 Rela ion be ween a e age o al amino acid
con en in milk and eed.
30.28
20.51
21.19 17.65
47.02
44.13 45.7 44.21
0
20
40
60
212 22 32
Con en o EAA g.kg-1
Lac a ion day
EAA
Milk
32.51
22.33
23.47 19.45
61.24
56.35 58.45
57.34
0
20
40
60
80
212 22 32
Con en o NEAA g.kg-1
Lac a ion day
NEAA
Milk
62.79
42.84
44.67 37.11
108.26
100.48 104.16101.57
0
50
100
150
212 22 32
Con en o TEAA g.kg-1
Lac a ion day
TEAA
Milk
Po a ina s o Slo ak Jou nal o Food Sciences
Volume 14 570 2020
inc eased om 17 o 22 g.kg-1 (Ma uzzi and Do eau,
2006). Fu he , a ios o o al EAA and NEAA con en in
milk o ha in eed on he lac a ion days obeyed he
ollowing alues 1:1.5, 1:2, 1:2 and 1:2.4, and 1:1.9, 1:2.5,
1:2.5 and 1:2.8, espec i ely. In he case o TAA con en ,
he a io was 1:1.7, 1:2.4, 1:2.4, and 1:2.7. On he o he
hand, hese a ios on he 5 h and 10 h days o he milk
pe iod we e consis en while ha ela ing o he 28 h day o
lac a ion sligh ly inc eased. I has been epo ed ha he
inges ion o high-quali y p o ein inc eases he AA
concen a ion in ma e’s milk (Glade and Luba, 1990).
Thus, he AA concen a ions in milk ound in his s udy
we e signi ican ly ela ed o AA concen a ions in he
eeds.
CONCLUSION
All esul s o his esea ch indica ed signi ican ela ions
and changes in majo mine als and amino acid
composi ion o di e en lac a ing ma es’ milk h oughou
he lac a ion pe iod and in eeds used o eed he ma es.
The a e age DM con en o he eed anged wi hin
89.2 ±0.72 % w/w (p <0.05). To al amino acid con en s in
all eed gene ally anged om 84.4 g.kg-1 o 117.0 g.kg-1
and he highes o al EAA con en was 51.7 g.kg-1 in 4F on
he 10 h day while he lowes EAA con en d opped o
38.4 g.kg-1 in 2F on he 5 h day; he majo EAAs we e
ep esen ed by leucine and a ginine, whose le els anged
wi hin 7.3 – 10.3 g.kg-1 and 6.37 – 9.59 g.kg-1,
espec i ely. Me hionine and his idine we e ound mino
EAAs wi h le els oscilla ing be ween 2.11 – 3.05 g.kg-1
and 2.48 – 3.60 g.kg-1, espec i ely. In he case o NEAA,
hei le els we e lowe compa ed o hose o EAAs
con en s, which anged be ween 66.8 g.kg-1 and
50.7 g.kg-1. Glu+Gln, Asp+Asn, and p oline we e he
majo NEAAs which ep esen ed app oxima ely 60% o
TNEAA. The a io o o al EAA o NEAA anged om
1:1.2 o 1:1.4. Gene ally, a e age o al AA con en in eeds
o he lac a ing ma es was ound a 105.0 g.kg-1.
Acco ding o esul s ob ained, he AA con en in all milk
samples a ied, which was caused by di e ences in ma es
and by a ia ions h oughou lac a ion days. The AA
con en s in 1P milk we e h ee imes lowe
(12.2 – 20.4 g.kg-1) compa ed o o he ma es. Wi h
excep ion o 1P, o al AA con en in 2-8 Ps caused by
b eed di e ences anged 21.9 – 54.6 g.kg-1,
33.6 – 70.7 g.kg-1, 38.1 – 71.2 g.kg-1, 29.5 – 74.2 g.kg-1,
52.2 – 87.1 g.kg-1, 37.9 – 70.3 g.kg-1 and 26.4 – 64.5 g.kg-
1, espec i ely, om he 2nd o 28 h day o lac a ion. The
a e age dec ease o o al amino acid con en eached
45.5% om he ini ial milk pe iod o he 2nd day o he
milking pe iod. The a e age o al AA con en s caused by
b eed di e ences on he 2nd, 5 h, 10 h and 28 h lac a ion
days eached le els a 62.8 g.kg-1, 42.8 g.kg-1, 44.7 g.kg-1
and 44.8 g.kg-1, espec i ely on he 2nd, 5 h, 10 h and 28 h
lac a ion days. Du ing he lac a ion pe iod, o al AA
composi ion did no change, bu hei amoun signi ican ly
al e ed. Conce ning TEAA in milk, he highes le els o
EAAs we e ep esen ed by a ginine, leucine, and lysine,
whose amoun s anged be ween 2.41 – 4.35 g.kg-1,
3.36 – 5.59 g.kg-1 and 2.7 – 4.8 g.kg-1, espec i ely while
he lowes EAAs we e exempli ied by his idine and
me hionine, whose le els oscilla ed be ween
0.9 – 1.6 g.kg-1 and 1.2 – 2.0 g.kg-1, espec i ely. The o al
NEAA con en was sligh ly highe han ha o EAA; he
TNEAA o TEAA a io was ound a 1:0.9 p oxima ely.
The majo NEAAs in milk we e ep esen ed by Glu+Gln,
Asp+Asn, and p oline, anging be ween 6.8 – 11.0 g.kg-1,
3.2 – 5.6 g.kg-1, and 1.3 – 2.2 g.kg-1, espec i ely. In
con as , le els o NEAA cys eine and glycine anged
wi hin 0.9 – 1.5 g.kg-1 and 0.6 – 1.2 g.kg-1, espec i ely.
Signi ican ela ionships be ween all he compa ed da a
we e obse ed; i was indica ed ha he de ia ions in each
amino acid le el in milk we e acco dingly co ela ed wi h
hose ound in eed on all days o lac a ion, excep he 2nd
one. O e all, he a ios o o al EAA and NEAA con en in
milk o ha in eed h oughou he lac a ion pe iod ollow
1:1.5, 1:2, 1:2 and 1:2.4; and 1:1.9, 1:2.5, 1:2.5 and 1:2.8,
espec i ely. In he case o TAA con en , he a io was
1:1.7, 1:2.4, 1:2.4, and 1:2.7.
Fu he s udies on ma e’s diges ion o p o eins, le els o
ee amino acids, and mine als in eed and on changes in
he nu ien s in blood and milk o he lac a ing ma e a e
sugges ed o cla i y changes in milk composi ion
depending on eeding sys ems.
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