South African Journal of Animal Science 2015 , 45 (No. 1) [600460]

South African Journal of Animal Science 2015 , 45 (No. 1)

URL: http://www.sasas.co.za
ISSN 0375- 1589 (print), ISSN 2221 -4062 (online)
Publisher: South African Society for Animal Science http://dx.doi.org/10.4314/ sajas.v45i1.1
Dietary effect of silage type and combination with camelina seed on milk fatty
acid profile and antioxidant capacity of sheep milk

D. Mierl ita# & S. Vicas
University of Oradea, Department of Animal Science, Oradea City, Romania

(Received 15 July 2014; Accepted 14 December 2014; First published online 7 February 2015)

Copyright resides with the authors in terms of the Creative Commons Attribution 2.5 South African Licence.
See: http://creativecommons.org/licenses/by/2.5/za
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Journal of Animal Science.
______________________________________________________________________________________
Abstract
The present study sought to quantify the differences between maize-based (MS) and grass -silage-
based (GS) diets in terms of their effect on the milk yield, milk fatty acid composition and antioxidant capacity
in dairy ewes, and to test the hypothesis that it is possible to improve yield, fatty acid (FA) composition and
antioxidant capacity by supplementi ng diet with camelina seed (Cs). Experimental diets consisted of a 2 x 2
factorial arrangement of type of silage (GS vs. MS) and camelina seed (− Cs vs. +Cs). Feeding the MS diets
increased net energy for lactation (NE L) intake, raw milk yield and fat, protein and lactose yields . Feeding
+Cs increased energy corrected milk (ECM), milk fat content and fat yield. Maize silage consumption is
associated with an increased proportion of hypercholesterolemic fatty acids (HFA) and a higher value of the
atherogenicity index. However, an MS diet led to an increased share of t11-C18:1 and c9,t11-conjugated
linoleic acid (CLA ) in milk. Milk FA profile in ewes fed GS diet was of higher quality for human beings owing
to higher concentrations of α -linolenic acid and a lower content of HFA. Supplementing with camelina seed
resulted in a higher concentration of t11-C18:1, c9,t11 -CLA and C18:3n-3 in milk fat. The t rolox equivalent
antioxidant capacity (TEAC) value of milk was higher in milk from MS -fed ewes compared with that of their
counterparts fed GS. Dietary supplementation with camelina seed increased the oxidative stability of milk
samples. These results suggest that grass -silage-based diet supplemented with camelina seed results in
milk of better quality for human consumption.
______________________________________________________________________________________
Keywords: Milk quality , oilseed, PUFA profile, oxidative stability of milk , TEAC assay
#Corresponding author: [anonimizat]

Introduction
Sheep milk fat is rich in saturated fatty acids (SFA), mainly C12:0, C14:0 and C16:0
(hypercholesterolaemi c fatty acids (HFA )), which have a negative effect on human health (Williams, 2000).
Oleic acid (C18:1 cis -9), α -linolenic acid (C18:3 n- 3; ALA), eicosapentaenoic acid (EPA, C20:5 n-3),
docosahexaenoic acid (DHA, C22:6 n-3) and conjugated linoleic acid (CLA, C18:2 cis -9 trans -11) have
positive effects on human health. They reduc e the risk of cardiovascular disease, are anti-carcinogenic , and
have anti-sclerosis properties (Massaro et al., 1999; Lopez -Huertas, 2010). Therefore, maximizing ALA,
EPA, DHA (poly -unsaturated fatty acid ( PUFA ) n-3: PUFA n -3) and CLA in milk and dairy products would
benefit human health.
Major changes in milk fatty acid ( FA) composition can be induced by manipul ating nutrition, such as
feeding pasture, conserved forages, starchy concentrates and diets supplemented with oilseeds (Ferlay
et al. , 2011). Supplementing ruminant diet s with oil (sunflower, soya, linseed, canola) has a stronger
negative effect on intake, fibre digestion, rumen metabolism and milk FA profile than seeds ( Chilliard et al.,
2003; Andrade et al., 2006). Using seeds as a source of fat is a more convenient practice than using oils,
because of their limited ruminal hydrogenation of FA (Chilliard et al., 2001).
Camelina ( Camelina sativa L.) is native to the Finland to Romania region, and east to the Ur al
Mountains. Because camelina seed contains a high concentration of long-chain unsaturated FA s (total
PUFA: 65. 8%; linoleic acid: 22. 1%; α -linolenic acid: 43 .7% (Mierlita et al., 2011)), its FA spectrum is similar
to that of fish oil (AbuGhazaleh et al., 2007; Hunter & Roth, 2010) and linseed (Hurtaud & Peyraud, 2007;
Cieslak et al., 2010) . Seeds rich in linoleic acid (e.g. soya and sunflower) can influence the C18:1 trans and
CLA profile in milk, while seeds rich in α -linolenic acid (e.g. linseed, camelina seed) affect primarily the C18:3
concentration in milk (Chilliard et al., 2003; Gomez -Cortes et al., 2009; Mierlita et al., 2011). In addition,

2 Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5

camelina seed contains gamma tocopherol (vitamin E), which acts as an antioxidant , and increases the
stability of oil compared with other oilseeds (Budin et al., 1995).
An increased proportion of unsaturated fat in milk may augment its oxidative susceptibility . To
maintain a high quality, the concentration of antioxidants should therefore be elevated (Slots et al., 2009). In
milk, the concentration of α -tocopherol and car otenoids as antioxidants is believed to be important for
oxidative stability. High concentrations of α -tocopherol and β -carotene in milk can be obtained from a high
proportion of pasture or grass clover silage in the diet of ruminants (Havemose et al., 2004; Renobales et al.,
2012) , because these types of forage are high in antioxidants (Lynch et al., 2001). Maize silage (MS) and
grass silage (GS) have great potential in the nutrition of ewes , especially over four to five months of winter
feeding when ewes are kept indoors. Milk production is higher when using maize silage than grass silage
owing to higher starch content and digestibility (Nie lsen et al. , 2006), which makes this system more
competitive in terms of production and economic outcome. However, comparisons between maize silage and
grass silage as sheep feed options have not been made in terms of their effects on the FA profile of the milk,
with particular reference to HFA, PUFA n -3 and CLA , which affect human health. In addition, studies on the
antioxidant activity of sheep milk are limited (Renobales et al. , 2012). Most of the published studies refer to
cows ’ milk (Chilliard & Ferlay, 2004), probably because of its large volume and economic importance,
although from a nutritional point of view, ovine milk is better than bovine milk (Renobales et al., 2012; Claeys
et al., 2014). The effect s of type of silage and supplementation of the ewes' diet with camelina seed on milk
FA profile and oxidative stability are not well documented.
Hence, the aim of this study was to find out whether the composition of milk could be manipulated to
become closer to recent dietary recommendations for human beings , and thus have a higher concent ration
of PUFA and a high oxidative stability by feeding ewes maize- and grass -silage-based diets and
supplementing with camelina seed ( Camelina sativa L).

Materials and M ethods
The study was conducted at the University of Oradea (Romania) over a 10-week period. The first three
weeks were used as a covariate period (week 1) and for adaptation to dietary treatments (weeks 2 and 3).
After weaning the lambs (72 ± 14 days in milk), 40 multiparous Turcana ewes (liveweight 44.9 ± 2.7 kg;
parity 2.4 ± 0.16) were divided in to four homogeneous groups (10 ewes/group). At the onset of the trial, ewes
averaged 744.7 ± 148.5 g/day milk yield containing 66.8 ± 11.2 g milk fat /L. The four groups were assigned
randomly to one of four dietary groups arranged in a 2 x 2 factorial design. The main treatment factor was
type of silage (grass or maize) and the second was type of supplement (with or without fat). The s ource of fat
was camelina seed ( Camelina sativa L.), which contains 37.6% crude fat , and has a high concentration of
PUFA (in particular linoleic acid: 22. 1% and α -linolenic acid: 43. 7%) (Mierlita et al., 2011). The diets of the
four ewe groups were as follows:
• GS/− Cs: grass -silage-based diet, with no supplement
• GS/+Cs: grass -silage-based diet, comple mented with 70 g/kg (DM ) diet of camelina seed
• MS/−Cs: maize-silage-based diet, with no supplements
• MS/+Cs: maize-silage-based diet comple mented with 70 g/kg DM diet of camelina seed
Grass silage was prepared from the vegetation on a meadow , with a plant species composition of ca.
57% Dactylis glomerata, 10% Phleum pratense, 8% Poa pratensis , 7% Festuca rubra, 13% legumes (mainly
Trifolium repens ) and 5% other grasses. Botanical composition was determined at mowing by calculating the
weight of 30 forage samples taken randomly by quadratic frame (0.25 × 0.25 m2) by manual separation of
plant species . The m eadow was harvested at the early flowering stage. Forage DM content at harvest was
284 g/ kg fresh sample. The crop was mown and allowed to wilt for 24 hours before harvesting with a round
baler. Bales were wrapped in four layers of plastic.
The maize crop ( Zea mays L .) was sown with a row space of 75 cm and 70 000 plants /ha. Whole crop
maize was harvested to a nominal stubble height of 20 cm above ground (pre-harvest DM of 305 g/ kg fresh
weight, while the cob DM to total DM ratio was 6 : 1).
Diets consisted of a total mixed ration (TMR ) (forage : concentrate ratio 70 : 30 on a DM basis ) (Table
1), formulated to be isonitrogenous. The diets were freshly prepared daily , and offered ad libitum as two
meals at 08:30 and 16:30. Refusals were removed and weighed prior to the morning feeding.
During weeks 2 and 3, the ewes were gradually switched to one of the four experimental diets: week 2
was for adaptation to the type of silage; and week 3 for adaptation to lipid supplementation.
The ewes were milked twice daily (07:30, 20:30) , and milk yield was recorded. Milk fat, lactose and
protein levels were recorded on two consecutive days each week. Samples from two consecutive milking
sessions were taken on week 6 and week 10 to determine the FA profile of milk fat.
Samples of the diets were collected in weeks 3, 5, 7 and 10 of the experiment period (n = 4), stored at
−20 șC, then used for chemical composition analysis. The diets w ere analy sed for DM (ISO, 1999a), n eutral

Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5 3

detergent fibre (NDF ) and acid detergent fibre (ADF ) (Van Soest et al., 1991) on a Fibersac analy ser (Ankom
Technology, Fairport, NY), nitrogen ( N) (Kjeldahl technique) and ether extract (AOAC, 1996). Starch of the
oven -dried materials was determined by a colorimetric method (Dubois et al., 1956).
Samples (n = 2) of di ets were collected on weeks 6 and 10 to determine the FA profile. These samples
were stored immediately at −20 șC, and later lyophilized and kept until analysis.
Milk samples were preserved with two tablets of Bronopol® (BroadSpectrum Micro- tabs II, D& F
Control Systems Inc., USA). The samples were refrigerated at 4 șC before being analysed for fat and protein
content by infrared analysis (Milk Analyser System 4000, Foss Electric, Hillerod, Denmark). Monohydrate
lactose content was measured on these samples using an enzymatic method (FIL, 1991). Samples of milk collected on weeks 6 and 10 for FA analysis were frozen at − 20 șC without preservatives.
To determine the concentration of FAs in the diets, fatty acid methyl esters (FAME) were prepared by
the one-step extraction- methylation method of Sukhija & Palmquist (1988). In order to determine the
composition of FAs in milk, the fat was extracted according to the international standard, ISO 14156 / IDF
172:2001. FAME were prepared according to the method proposed by Christie (1982) and Chouinard et al.
(1999) and were determined by gas chromatography using a Varian GC 3600 equipped with FID and a fused
silica capillary column (SP 2560 Supelco), 100 m × 0.25 mm i.d., f ilm thickness 0.20 μm. Helium was used
as the carrier gas at a flow rate of 1 mL/min. The split ratio was 1 : 100. The oven temperature was
programmed at 90 șC and held for 1.50 min, then increased to 210 șC at a rate of 9 șC/min, held at this
temperature for 25 min, then increased to 230 șC at 15 șC/min, and held for 7 min. The temperatures of the
injector and the detector were set at 270 șC. The FA identification was based on external standards, and
calculation of the distribution (in weight percentage) was based on the area of each FA ester corrected for
the response factors for the individual FAs. Internal standards were used to determine the percentage of
recovery. The CLA isomer reported is cis-9, trans -11 C18:2. The percentage of each FA was calculated by
dividing the area under the FA peak by the sum of the areas under the total reported FA peaks.
Antioxidant activity of milk and experimental diets samples was estimated by the TEAC method,
according to Renobales et al. (2012) , which meas ures the ability of compounds to scavenge the 2,2'-azino-
bis(3 -ethylbenzthiazoline-6 -sulphonic acid) (ABTS) radical cation in relation to trolox . ABTS was dissolved in
distilled water to a 7 mM concentration. ABTS
+ was produced by reacting ABTS stock solution with 2.45 mM
potassium persul phate and allowing the mixture to stand in the dark at room temperature for 12 – 16 hours
before use. ABTS stock solution was diluted with saline phosphate buffer (0.15 M, 5 mM phos phate, pH 6.7)
in order to obtain an absorbance of 0.70 ± 0.02 at 730 nm. After adding 0.5 m L of various concentrations of
trolox (0 – 20 µM) or milk samples to 2.0 mL of diluted ABTS+ (working solution), the absorbance was read at
730 nm after 10 minutes at 25 șC. A blank sample was used to correct the residual turbidity. In the milk
samples the results were expressed as µmol t rolox equivalent normalized according to the protein content of
each milk sample (µmol trolox equivalent/g protein), and for experimental diets as µmol t rolox equivalent/100
g. The pH of milk samples w as adjusted to 6.7, and diluted 10 times before measurements.
The atherogenicity index (AI) was calculated according to Chilliard et al. (2003) as follows:
(C12:0 + 4 x C14:0 + C16:0)/( MUFAs + PUFAs).
The data for the chemical composition of experimental diets, milk yield, milk compositions, FA in milk
fat and TEAC were analy sed as a 2 × 2 factorial randomized block design using the PROC MIXED models of
SAS Institute (SAS, 2001). Fixed effects were the type of silage (GS and MS), camelina seed
supplementation (Cs) , interactions between them (silage x Cs), time and an appropriate covariate. Random
effect s of ewe were used as the error term. Variance-covariance structure was first autoregressive ( AR(1) ).
For FA proportion in milk fat, analysis was performed without covariate. Overall differences between
treatment means and interacti on for silage type and camelina seeds were considered significant at P <0.05.
Trends for significance were declared at P = 0.05 to 0.10.

Results and Discussion
The c hemical composition of the experimental diets is presented in Table 1 and FA levels and
antioxidant capacity of diets in Table 2. As expected, the MS diets had the highest starch content, while diets
+Cs had the highest content of crude fat ( P <0.001). The two feeding systems offered similar protein and net
energy for lactation (NE L – MJ/kg) contents.
Diets based on g rass silage had a higher PU FA concentration, especially PUFA n-3, compared with
the maize-silage diets, which had a higher PUFA n-6 content. Supplementing the ewes’ diet with camelina
seeds doubled the FA level in the diet and improved their profile through the increase in PUFA n-3
concentrations and the decrease in the proportions of saturated FA s (Table 2). Although the plant belongs to
the Crucifera family, camelina seeds have a high content of PUFA, especially α -linolenic acid (C18:3 n-3),
which is comparable with the concentrations in linseed (Hurtaud & Peyraud, 2007; Cieslak et al. , 2010). The
antioxidant capacity of the diets registered higher values with the MS diets because wilting of the grassy

4 Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5

meadow for 24 hours probably led to the de struction of antioxidizing factors such as carotenoids and
tocopherols , since 80% of the carotenoid content of grass is known to be destroyed in the process of making
hay (Chauveau-Duriot et al. , 2005). The camelina seeds induced a higher TEAC value (trolox equivalent
antioxidant capacity) in +Cs diets, possibly owing to the high tocopherol content, which have high antioxidant
activity (Budin et al. , 1995).
Feeding the MS diets increased NE L intake, raw milk yield and fat, protein and lactose yields (Table 3).
Feeding +Cs increased energy -corrected milk (ECM), milk fat content and fat yield ( P <0.01). Milk lactose
level was not affected by dietary factors. The raw milk yield, milk fat and mil k protein levels were relatively
constant (effect of wk: P >0.10) during the trial (data not shown). An increase in milk protein concentration
may be attributed to microbial protein synthesis being energetically more efficient on MS than on GS -based
diets (Givens & Rulquin, 2004).
The type of silage in the diet had no effect on milk fat content. Typically, increases in starch intake,
such as from the MS diets, are associated with a reduction in milk fat (Lock & Shingfield, 2004; Nielsen et al. ,
2006). A lack of effect on milk fat concentrations in this experiment may reflect an equal intake of NDF i n the
MS and GS diets (Kliem et al. , 2008).

Table 1 Ingredients and chemical composition of experimental diets

Grass silage Maize silage
SEM P values of effects1
Fat supplementation −Cs +Cs −Cs +Cs S Cs S x Cs
Ingredients (g/100 g of dry matter)
Maize silage – – 45.0 45.0

Grass silage 45.0 45.0 – –
Lucerne hay 25.0 25.0 25.0 25.0
Maize
Soybean meal 21.3
7.0 17.8
3.5 18.3
10.0 15.3
6.0
Camelina seed – 7.0 – 7.0
Calcite2
Sodium bicarbonate
Trace -mineralized salt
Vitamin mix 0.5
0.7
0.3
0.2 0.5
0.7
0.3
0.2 0.5
0.7
0.3
0.2 0.5
0.7
0.3
0.2
Chemical composition of experimental diets
Dry matter (D M) 63.7 63.8 64.2 64.3 17.1 NS NS NS
CP (% of DM) 14.88 14.85 14.59 14.57 0.88 NS NS NS
Crude fat (% of DM) 3.39 6.27 3.09 6.01 0.84 NS *** NS
Starch (g/kg DM) 304.3 289.1 386.0 374.5 12.73 ** NS †
NDF (% of DM) 37.0 37.3 29.9 30.2 1.67 ** NS NS
ADF (% of DM) 23.6 23.9 18.6 18.9 0.83 ** NS NS
PDIN3 (g/kg DM) 98.3 99.1 101.6 101.2 1.12 NS NS NS
PDIE3 (g/kg DM) 82.1 83.7 99.3 100.4 0.94 * NS NS
NEL4 (MJ/kg DM) 6.26 6.31 6.33 6.38 0.51 NS NS NS

Cs: camelina seed ( with no supplements: − Cs; completed with: +Cs) ;
SEM: standard error of mean .
CP: crude protein; NDF : neutral detergent fibre; ADF = acid detergent fibre.
1 S: effect of type of silage; Cs: effect of camelina seed; S x Cs: interaction between type of silage and camelina
seed .
*** P <0.001; ** P <0.01; * P <0.05; †: P <0.10; NS: P >0.10.
2 Contained 38.5% Ca .
3 Calculated values (INRA, 1989). PDIN and PDIE : digestible CP in the intestine from microbial protein synthesis
when availability of fermentable N in the rumen is limiting, and from microbial protein synthesis when availability of energy in the rumen is limiting, respectively .
4 NEL: net energy for lactation. The value of NE L was estimated according to INRA (1989 ).

Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5 5

Table 2 Fatty acid (FA) profile and antioxidant capacity for experimental diets1

Treatment2
Grass silage Maize silage
Fat supplementation −Cs +Cs −Cs +Cs

Fatty acids (g/kg DM) 27.2 56.1 27.0 54.8
Fatty acid composition (% of FAME)
C12:0 0.19 0.21 0.36 0.48
C14:0 0.92 0.91 0.47 0.47
C16:0 19.37 18.51 16.43 15.58
C16:1 n-9 0.60 0.56 0.65 0.61
C18:0 4.12 4.09 3.87 3.85
C18:1 n- 9c 11.85 11.07 22.05 21.31
C18:1 n- 7c 0.80 0.78 0.95 0.96
C18:2 n- 6c 37.3 35.4 43.7 41.6
C18:3 n- 6 0.37 0.46 0.19 0.28
C18: n- 3 21.80 24.34 8.94 11.48
C20:1 0.84 1.65 0.72 1.53
C22:1 ND 0.22 ND 0.23
Others 1,84 1.79 1.71 1.59
SFA3 24.60 23.72 21.13 20.38
MUFA4 14.09 14.28 24.37 24.63
PUFA5 59.6 60.2 52.8 53.4
PUFA n -6 37.7 35.9 43.9 41.9
PUFA n -3 21.80 24.34 8.94 11.48
TEAC (µmol TE/100 g diet) 95.4 99.2 109.5 113.4

1Data presented are least square means (n = 2), except for total antioxidant capacity (n = 4 samples per diets).
2GS: grass silage; MS : maize silage; Cs : camelina seed ( with no supplements: − Cs; completed with: +Cs) ;
FAME : fatty acid methyl esters; ND : not detected .
3 SFA: saturated FA (C12:0 + C14:0 + C16:0 + C18:0);
4 MUFA : monounsaturated fatty acids (C16:1 + C18:1 + C20:1 + C22:1);
5 PUFA : polyunsaturated fatty acids (C18:2 + C18:3) .
TEAC: trolox equivalent antioxidant capacity ( µmol trolox equivalent/100 g diet).

The inclusion of fats rich in PUFA in the diet of dairy cows causes a decrease in milk fat yield, known
as the milk fat depression (MFD) syndrome. T he opposite appears to occur with dairy ewes supplemented
with camelina seed (+Cs ), which increased their milk fat yield. These discrepancies between species could
be because of the low amounts of trans FA ( trans -10 C18:1, trans -10, cis-12 C18:2, and trans -9, cis-11
C18:2) in ewe milk fat that were proposed in cow milk fat synthesis inhibitors (Gomez -Cortes et al. , 2008).
Previous studies reported that grass and maize silage alter the FA composition of cows’ milk (Nielsen
et al. , 2006; Ferlay et al. , 2011). The current study was designed to examine changes in milk FA composition
when diets based on grass or maize silage were supplemented with a constant proportion of concentrate
with camelina seed. It was conducted in order to develop practical nutritional strategi es to reduce milk fat
SFA and HFA content , increase PUFA, and improve the oxidative stability of sheep milk.
The effect s of the treatments on the FA profile of milk fat and antioxidant capacity are presented in
Table 4. There were significant effects of ty pe of silage on C12:0, C14:0, C14:1, C15:0, C16:0, C17:0, C17:1,
C18:1, C18:1 trans -11 (TVA: trans -vaccenic acid), cis -9 trans -11 CLA (rumenic acid-RA), C18:3 n-3 (ALA:
α-linolenic acid) and C20:5 n-3 (EPA: eicosapentaenoic acid) ( P <0.05) concent rations. The remaining milk
FA levels were not affected significantly by type of silage.
Ewes in the MS group exhibited a higher level of milk fat of C12:0, C16:0, C17:0, C17:1, TVA and cis –
9 trans -11 CLA than the GS group ( P <0.01). By contrast, the C14:0, C15:0, C18:1 cis -9, C18:3 n-3 (ALA)

6 Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5

and C20:5 n-3 (EPA) contents were higher in the milk fat of the GS group ( P <0.01). When dairy ewes were
fed diets MS with high non-fibrous carbohydrates (NFC) that is, sugars, starch, and soluble fibr e, the
concent rations of TVA and c9,t11 CLA in milk increased, indicating that when the NFC in the diet is raised ,
the biohydrogenation of unsaturated FA in the rumen probably slows down, and a higher amount of
unsaturated FA escapes the rumen, reaching the mammary gland. Maize silage may enhance the growth of
specific bacteria in the rumen, stimulating the production of CLA and the reduction of TVA to stearic acid
(C18:0) (Nudda et al. , 2006). In this sense, the MS diet is richer in C18:2 n-6 ( 43.66 vs. 37.30) (Table 2),
which can stimulate CLA production. Increases in the concentrations of C14:0, C15:0, cis-9 C18:1 (oleic
acid) and cis -11 C18:1 in milk fat and a decrease in the concentration of C16:0 were recorded in cows fed on
grass silage co mpared with those fed on maize silage (Vlaeminck et al. , 2006). A more complete
hydrogenation of PUFA into C18:0 in rumen probably helped the increase in oleic acid in milk fat, as this FA
is endogenously synthesized in the mammary gland via Δ9-desaturase of C18:0 (Chilliard et al. , 2003).
The GS ewes presented a significantly greater ratio of PUFA n-3 in the milk than the MS group ( P
<0.01), which is consistent with their higher proportion in grass silage than in maize silage (Table 2). Total
PUFA s in milk were greater in the GS group than in the MS group owing to the greater amount of α-linolenic
acid (C18:3 n-3) and EPA (C20:5 n-3) in milk from GS ewes than in milk from MS ones. The EPA increase in
the GS sheep milk was probably owing to de novo synthesi s of the FA from C18: 3 n-3 in the mammary
gland, since the GS diet has a much higher content of linolenic acid than the MS diet (21.80 vs. 8.94) (Table
2).

Table 3 Production parameters of dairy ewes fed grass silage (GS) or maize silage (MS ) diets with (+Cs) or
without (− Cs) camelina seed
1

Grass silage Maize silage
SEM P values of effects2
Fat supplementation −Cs +Cs −Cs +Cs S Cs S x Cs

DMI (kg/day) 2.848 2.795 3.081 3.032 0.074 * NS NS
Milk yield (g/day) 704.6 775.8 786.5 810.1 26.4 * * *
ECM3 (kg/day) 0.653 0.729 0.750 0.795 0.041 ** * *
Milk fat (g/L) 66.9 68.3 67.9 72.7 1.23 NS ** †
Milk protein (g/L) 53.4 54.0 58.0 56.6 0.62 * NS NS
Milk lactose (g/L) 47.8 48.9 48.1 48.0 0.46 NS NS NS
Fat yield (g/day) 47.2 53.0 53.4 58.9 1.72 * ** *
Protein yield (g/day) 37.6 41.9 45.6 45.8 0.59 * NS †
Lactose yield (g/day) 33.6 38.0 37.9 38.9 0.84 * * NS
NEL intake (MJ/day) 17.8 17.6 19.5 19.3 0.22 * NS NS

1 n = 10 ewes per group .
2 S: effect of type of silage; Cs: effect of camelina seed; S x Cs: interaction between type of silage and camelina
seed .
*** P <0.001; ** P <0.01; * P <0.05; †: P <0.10; NS: P >0.10.
3 Energy corrected milk : ECM = milk yield (kg/d) x (0.071 x fat (%) + 0.043 x CP (%) + 0.2224) .
SEM: standard error of mean .

A significantly higher share of hypercholesterolaemic FA s (HFA: C12:0 + C14:0 + C16:0) was found in
the milk of sheep in the MS group compared with GS group of sheep ( P <0.05), probably owing to the high
consumption of starch in the maize silage, which is associated with increased de novo synthesis of saturated
FA, resulting in increased milk level (Kalac & Samkova, 2010). The high concentration of starch in the diet
increases FA biohydrogenation in the rumen and reduces the flow of linoleic acid and linolenic acid to the
duodenum (Chilliard et al. , 2003).
Milk fat from MS diet ewes (supplemented or not with Cs) had more than 30% c9,t11-CLA isomer than
milk fat from the GS diet ewes (Table 4). This positive effect of maize-silage intake on milk fat c9,t11-CLA
content has previously been found in dairy cows ( Nielsen et al. , 2006; Samkova et al. , 2009). While
Samkova et al. (2009) found a significant difference in CLA level (0.48% and 0.92% after feeding cows

Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5 7

maize and grass silage, respectively), Shingfield et al. (2005) did not find any significant effect of silage type
on total CLA and c9,t11-CLA proportions.
Dietary camelina seed modified milk FA composition towards a lower level of SFA and a higher level
of PUFA and MUFA, confirming that an adequate dietary strategy can improve sheep milk quality. Including
camelina seed in the diet resulted in a significant increases in rumenic acid (c9,t11-CLA) and vaccenic acid
(t11-C18:1), as well as α -linolenic acid (C18:3) in milk fat ( P <0.01). Interactions among silage type and
camelina seed resulted in a significant increase in rumenic acid, α -linolen ic and oleic acids ( P <0.05). Group
MS/+Cs milk had the highest concentration of the isomer c9,t11-CLA and TVA.
The amount of the CLA isomer cis-9, trans -11 in the milk of group +Cs was higher by 37.7% than the
level present in the milk of group − Cs, which is higher than the increase obtained with sunflower oil (Gómez –
Cortés et al. , 2011), but not as high as the 4.4-fold increase obtained with a mixture of 2% sunflower and 1%
fish oil (Toral et al. , 2010). The concentration of TVA in the milk of group +Cs w as 1.4 -fold higher than that of
group − Cs, lower than the 4.7-fold increase reported by Gómez -Cortés et al. (2011) for the diets containing
5.1% sunflower oil and the 5.1- fold value obtained with the mixture of sunflower and fish oils (Toral et al. ,
2010). The increase in TVA concentration in the +Cs ewes' milk is important because the vaccenic acid in
human tissues can be converted to the c9,t11-CLA isomer (Turpeinen et al. , 2002).
Butyric acid levels (BA – C4:0) in milk fat during the experiment were not affected by experimental
diets. In contrast to our results, Puppel et al. (2013) observed a significant increase in BA levels in milk from
cows receiving diets suppl emented with fish oil.
Unlike the results obtained in the present study , in dairy cows camelina seeds did not cause an
increase in C18:3 concentration in milk fat, despite an intake of 630 g camelina seed/day (Hurtaud &
Peyraud, 2007). This is probably because of substantial hydrogenation of C18:3 in the rumen and perhaps
incomplete digestibility of oils in seed form with the Cs diet. In the present study, the digestibility of camelina
seeds might not have been sufficiently efficient to make oil rapidly available to ruminal microorganisms,
and/or the quantity of added fat was not high enough to alter FA biohydrogenation.
The reduction of medium -chain FA (C12-C14) concentration by camelina seed supplementation
observed in this study is consistent with that reported by Gomez -Cortes et al. (2009) for diet with extruded
linseed supplementation.
Ewes fed +Cs combined with grass silage diet had the lowest proportion of C12:0, C16:0 and C17:0
(S x Cs: P <0.10 to 0.05) in milk fat; conversely they had the highest proportion of c9-C18:1, C18:3 n-3,
C20:5 n-3 and C22:6 n-3 in milk fat (S x Cs: P <0.05 to 0.001). Ewes fed +Cs combined with the maize
silage diet had the lowest proportion of C14:0, C15:0, C20:0 (S x Cs: P <0.10 to 0.05) in milk fat; conversely
they had the highest proportion of t11-C18:1 and c9,t11 -CLA (S x Cs: P <0.10 to 0.05).
The decrease in C12:0, C14:0 and C16:0 concentrations resulted in the reduction of the milk fat
atherogenic index (AI) of GS diet ewes and those whose diet was supplemented with camelina seed (+Cs),
compared with MS diet and − Cs diet respectively ( P <0.05) (Table 4).
Ratios of product/(substrate + product) were estimated to assess the extent of desaturation of specific
FAs during milk fat synthesis (Mele et al. , 2006). The higher values of these ratios indicate that the
desaturation of FA substrates is more intense in ewes that were not fed camelina seeds . Our results were
consistent with those reported by Mierlita et al . (2011) with ewes grazing on native pasture and completing
diet with grain and camelina seed, and by Bernard et al. (2005) for dairy goats fed a hay -based diet
supplemented or unsupplemented with linseed or sunflower oil. The data indicate that the FA composition of
milk can be improved from a human health perspective by including grass silage in the diet and
supplement ing it with camelina seed.
Increase in unsaturated nutritionally beneficial FAs can contribute to increased oxidation susceptibility
of milk fat and adverse changes in the nutritional and dietetic properties of milk. The researchers found a
variation in antioxidant activity between the milk from GS group sheep and the MS group (Table 4). The
TEAC ( trolox equivalent antioxidant capacity) value was significantly higher in the milk from the MS sheep
group ( P <0.01) compared with the GS group (0.133 vs. 0.105 µmol t rolox equivalent/g protein) owing to
higher concentrations of cis-9, trans -11 CLA, which have been shown to have a high antioxidant activity
(Park et al. , 2007). The trend of decreasing oxidative stability of milk in a grass -silage-based diet may be
owing to a higher degree of lipid oxidation caused by higher levels of C18:3 n-3. Similar results on t he
antioxidant activity of milk were obtained by Havemose et al. (2006) in cows fed grass – or maize-silage-
based diets.
Supplement ing ewe diet s with camelina seed led to an increase in TEAC values in milk samples by
44.2% – 84.5% ( P <0.001), the increase being higher in the grass -silage-based diet. This rise in the
antioxidant capacity of milk was because of augmented levels of natural antioxidants (tocopherols and

8 Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5

Table 4 Fatty acid profile (% of FAME) and antioxidant capacity of milk fat from dairy ewes fed grass silage
(GS) or maize silage (MS) diets c ombined with (+Cs) or without (− Cs) camelina seed1

Fat acids Grass silage Maize silage
SEM P values of effects2
−Cs +Cs −Cs +Cs S Cs S x Cs
C4:0 2.85 2.33 2.86 2.53 0.167 NS NS NS
C6:0 2.37 2.20 2.49 2.59 0.148 NS NS NS
C8:0 2.48 2.19 2.32 2.05 0.161 NS NS NS
C10:0 7.57 7.27 7.87 7.50 0.245 NS NS NS
C12:0 4.19 2.30 6.94 4.41 0.092 ** ** †
C14:0 9.25 8.22 8.28 7.54 0.627 ** * *
C14:1 0.12 0.11 0.29 0.42 0.016 * ** **
C15:0 0.89 0.81 0.46 0.20 0.065 *** ** **
C16:0 20.66 18.78 24.25 23.94 1.081 ** * †
C16:1 0.65 0.58 0.69 0.68 0.056 NS NS NS
C17:0 0.56 0.53 1.41 0.84 0.195 *** ** *
C17:1 0.31 0.24 0.73 0.58 0.027 *** † NS
C18:0 13.30 12.94 13.01 12.93 0.562 NS NS NS
C18:1 n9t 0.52 0.75 0.28 0.50 0.078 ** * *
C18:1 trans -11 (TVA) 2.88 4.16 3.65 5.28 0.191 * ** NS
C18:1 n9c 24.1 25.6 18.2 20.0 0.868 *** * NS
C18:1 cis-11 0.77 0.92 0.45 0.60 0.068 ** * NS
C18:2 n6t 0.35 0.39 0.30 0.30 0.028 NS NS NS
C18:2 n6c 1.66 2.80 1.37 1.59 0.180 NS * *
cis-9, trans -11 CLA 1.67 2.30 2.24 2.83 0.169 ** ** *
C18:3 n- 3 (ALA) 1.75 3.27 0.83 1.64 0.042 ** *** *
C20:0 0.37 0.35 0.53 0.26 0.017 * * *
C20:4 0.19 0.16 0.17 0.18 0.011 NS NS NS
C20:5 n- 3 (EPA) 0.32 0.36 0.21 0.28 0.024 * NS NS
C22:6 n- 3 (DHA) 0.30 0.45 0.22 0.37 0.029 † * NS
Total n- 3 FA 2.37 4.08 1.26 2.29 0.151 ** *** *
n-6/n-3 1.63 1.38 2.55 2.14 0.037 * † NS
Saturated FA 64.5 57.9 70.4 64.8 0.861 ** *** †
Unsaturated FA 35.6 42.1 29.6 35.2 0.552 *** *** *
Monounsaturated FA 29.3 33.4 24.2 28.0 0.674 ** ** *
Polyunsaturated FA 6.24 8.73 5.35 7.19 0.317 * *** NS
HFA3 34.1 29.3 39.5 35.9 0.591 * * †
AI4 1.74 1.28 2.17 1.66 0.107 * * NS
Δ9 – desaturase ratios:
18:1/18:0 + 18:1 0.71 0.68 0.67 0.63 0.043 * * NS
RA/TVA + RA 0.37 0.35 0.38 0.35 0.025 NS * NS
TEAC (µmol TE/g protein) 0.105 0.192 0.133 0.197 0.031 * *** **
1 n = 10 ewes per group; FAME : fatty acid methyl esters; SEM : standard error of mean .
2 S: effect of type of silage; Cs: effect of camelina seed; S x Cs: interaction between type of silage and camelina
seed. *** P <0.001 ; ** P <0.01; * P <0.05; †: P <0.10 ; NS: P >0.10 .
3 Hypercholesterolaemic fatty acids ( C12:0 + C14:0 + C16:0).
4 Atherogenicity index (AI = (C12 :0 + (C14:0 x 4) + C16:0 )/U nsaturated FA).
FA: fatty acid ; TVA: trans -vaccenic acid; CLA : conjugated linoleic acid ; ALA : acid α -linolenic; EPA :
eicosapentaenoic acid; DHA : docosahexaenoic acid ; TEAC: trolox equivalent antioxidant capacity .

Mierlita et al., 2015 . S. Afr. J. Anim. Sci. vol. 4 5 9

phytosterols) of camelina seed (Budin et al. , 1995; Zubr & Matthaus, 2002), which provide a better oxidative
stability of PU FA in camelina oil than fish oil and other vegetable oils rich in PUFA (Ni Eidhin et al. , 2011). An
increase in the total antioxidant status was noted in the milk of cows whose diets were supplemented with
fish oil and linseed (Puppel et al. , 2012).

Conclusions
This study showed that the maize silage diets may result in higher concentrations of cis -9, trans -11
CLA and trans -11 C18:1 and a lower C18:3 n-3 in milk fat. Camelina seed s are important sources of PUFA,
especially α -linolenic acid, which positively affects the milk FA profile. Milk fat from ewes fed grass silage
seem ed to have a nutritionally more propitious composition than fat from ewes fed maize silage.
Supplementing ewe diet s with camelina seed could improve the nutritional quality of milk fats, owing to
higher concentrations of α -linolenic acid and nutritionally beneficial trans -FAs (such as CLA and TVA) and
the lower content of HFA. The best FA profile in milk in terms of human health effects was obtained from
sheep fed a grass -silage-based diet and supplemented with camelina seed. Supplem entation with camelina
seed has prove d useful in providing the most complete human food from an antioxidant perspective. Thus,
the nutritional quality and safety of the food can be increased through reducing the oxidizing decay of fat in
the milk, which can lead to the formation of toxic secondary compounds and the development of smells and
aromas unspecific to milk.

Acknowledgements
This work was supported by CNCSIS –UEFISC DI, project number PN II – IDEI 679/2008.

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