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Proceedings of the 5th Australasian Dairy Science Symposium 2014405
Replacing maize with palm kernel expeller in dairy concentrates fed to Jersey cows grazing
kikuyu pasture
R. MEESKE1#, J.D.V. VAN WYNGAARD2
1
Western Cape Government, Dept. Agriculture, P.O. Box 249, George, 6530, South Africa
2
Western Cape Agricultural Research Trust, P.O. Box 249, George, 6530, South Africa
#
Corresponding author: [email protected]
ABSTRACT
High-fibre by-products have the potential to partially replace maize in the concentrate for dairy cows. Palm
kernel expeller (PKE) is a low-cost, high-fibre by-product from the palm-oil industry. The aim of the study was
to determine the effect of partially replacing maize with PKE in dairy concentrates for Jersey cows grazing
kikuyu pasture on milk production and milk composition. The study was conducted from January to April
2014 at the Outeniqua Research Farm situated near George in the Western Cape, South Africa. Seventy two
multiparous high producing Jersey cows (n=18 per treatment) were blocked according to milk yield (20.1±1.93
kg/cow/d), days in milk (111±41 d) and lactation number (3.4±1.34) and randomly allocated within blocks to
four treatments (PKE0, PKE10, PKE20 and PKE30). The PKE inclusion in the PKE0, PKE10, PKE20 and
PKE30 concentrate treatments was 0, 10, 20 and 30%, respectively, replacing part of the maize and soybean
oilcake in the concentrate. Concentrates were balanced to be iso-nitrogenous. All cows grazed kikuyu pasture
as one group and concentrate was fed at 6 kg as is/cow/d in the dairy parlour during milking (3 kg/milking).
Pasture was allocated at 11.1 kg DM/cow/d above a height of 30 mm. Cows had ad libitum access to PKE for
7 d on pasture prior to the start of the study. The study consisted of a 14 d adaptation period followed by 60 d
measurement period. Milk yield was recorded daily and milk composition was determined fortnightly. Milk
yield and milk fat content differed between treatments (P<0.05) and were 15.6, 15.4, 15.3 and 14.3 kg/cow/d
and 4.63, 4.93, 5.06 and 5.29% for the PKE0, PKE10, PKE20 and PKE30 treatments, respectively. The PKE
inclusion level in concentrates did not affect (P<0.05) fat corrected milk (FCM), milk protein and milk lactose
content of cows. It is concluded that PKE increased milk fat content at the 20 and 30% inclusion level and
sustained FCM at the 10, 20 and 30% inclusion level of concentrate fed at 6 kg/cow/d to cows grazing kikuyu
pasture during summer.
Keywords: By-product, alternative feedstuff, high-fibre, milk production, milk composition, grazed pasture.
INTRODUCTION
Maize is often the main ingredient in concentrates
fed to cows on pasture. However, high-fibre byproducts have the potential to partially replace maize
and create a more optimal rumen environment in
cows grazing high quality pasture (Bargo et al. 2003).
The availability and cost of by-products as well as
the impact on milk production, milk composition and
feed cost will determine to what extent by-products
can replace maize in the concentrate. Palm kernel
expeller (PKE) is a low-cost, high-fibre by-product
from the palm-oil industry. The aim of the study was
to determine the effect of partially replacing maize
with PKE in dairy concentrates for Jersey cows
grazing kikuyu pasture during summer, on milk
production and milk composition.
MATERIALS AND METHODS
The study was conducted from January to April
2014 at the Outeniqua Research Farm situated near
George in the Western Cape Province, South Africa.
Seventy two multiparous Jersey cows (n=18 per
treatment) were blocked according to milk yield
(20.1±1.93 kg/cow/d), days in milk (111±41 d)
and lactation number (3.4±1.34) and randomly
allocated within blocks to four treatments (PKE0,
PKE10, PKE20 and PKE30). The PKE inclusion in
the PKE0, PKE10, PKE20 and PKE30 concentrate
treatments was 0, 10, 20 and 30%, respectively,
replacing part of the maize and soybean oilcake
in the concentrate. The ingredient composition of
concentrates is given in Table 1. The concentrates
were balanced to be iso-nitrogenous. Molasweet
(Nutec Explicit Nutrition, Block G, Hilton Quarry
Office Park, 400 Old Howick Road, Hilton, KZN,
South Africa), a powdered feed flavour, was added
at 160 g/t to all concentrates. The PKE included in
this study had a DM, CP, NDF and EE content of
90.4%, 19.0%, 78.4% and 9.29%.
406
R. Meeske – Replacing maize with palm kernel expeller in dairy concentrates fed to Jersey cows grazing kikuyu pasture
Table 1: The ingredient and nutrient composition of concentrates with different levels of palm kernel expeller
(PKE) fed at 6 kg/d to Jersey cows grazing kikuyu pasture during summer.
Ingredient (%, as fed)
Maize
PKE
Soybean oilcake
Molasses
Feedlime
Salt
MgO
Premix2
Nutrient (% of DM)
CP
ME (MJ/kg)3
NDF
Starch
EE
Ca
P
Mg
PKE0
80.6
0
11.5
5
1.5
0.6
0.3
0.5
Treatment concentrate1
PKE10
PKE20
73.2
65.7
10
20
9.0
6.6
5
5
1.4
1.4
0.6
0.6
0.3
0.2
0.5
0.5
PKE30
58.3
30
4.1
5
1.3
0.6
0.2
0.5
12.1
12.5
8.9
62.4
3.85
0.67
0.37
0.31
12.0
12.3
14.9
53.9
4.28
0.67
0.39
0.31
12.0
11.9
26.8
36.9
5.13
0.66
0.43
0.32
12.0
12.1
20.8
45.4
4.70
0.66
0.41
0.31
PKE0 – concentrate containing 0% PKE; PKE10 – concentrate containing 10% PKE; PKE20 – concentrate
containing 20% PKE; PKE30 – concentrate containing 30% PKE; PKE – palm kernel expeller
2
Premix (Coprex Dairy Premix; per unit of premix) – 6 million IU vitamin A; 1 million IU vitamin D3; 8000
IU vitamin E; 100 g Zn; 50 g Mn; 20 g Cu; 1.7 g I; 1 g Co; 300 mg Se
3
ME (MJ/kg) = 0.84 x Gross energy x In Vitro Organic matter digestibility (ARC, 1984)
1
All cows strip-grazed kikuyu pasture as one
group. The botanical composition of the study paddock
consisted of 70% kikuyu, 10% other grasses, 5%
legumes and 15% weeds. Pasture was top-dressed
with 42 kg of N/ha after each grazing using limestone
ammonium nitrate (28% N). Pasture yield pre- and
post-grazing was estimated by measuring pasture
height with a rising plate meter (RPM; 100 readings/
strip) using a regression (Y = 87.63H - 195.11; Y =
pasture yield; H = RPM height; R2 = 0.86). Pasture
was allocated at 11.1±1.3 kg DM/cow/d above 30 mm.
Concentrates were fed at 6 kg (as fed)/cow/d in the
dairy parlour during milking (3 kg (as fed)/milking).
Cows had ad libitum access to PKE for 7 d on pasture
prior to the start of the study. The study consisted of a
14 d adaptation period followed by 60 d data collection
period. Milk yield was recorded daily using a 20-point
Dairy Master swing over milking machine with weighall electronic milk meters. Milk composition was
determined fortnightly and analysed according to (Van
Wyngaard 2013). Body weight (BW; Tru-Test EziWeigh
v. 1.0 scale, 0.5 kg accuracy, Auckland, New Zealand)
and body condition score (BCS; scale 1-5, Wildman et
al. 1982) were determined over two consecutive days at
the start and the end of the data collection period. Milk
production, milk composition, BW and BCS data were
subjected to an analysis of variance (ANOVA). Tukey’s
test was used to confirm the results of the ANOVA
and compare the treatment means at a 5% significance
level. The null hypothesis was: Ho: μ1 = μ2 = μ3 = μa.
The null hypothesis was rejected where P<0.05. Least
squares means were used to calculate a pooled standard
error of treatment means. Shapiro–Wilk tests were used
to test for normality (Shapiro and Wilk 1965).
RESULTS
Pasture height on the RPM and pasture yield
above 30 mm was 27.2±5.52 and 2185±483 kg
DM/ha and 10.1±1.42 and 692±124 kg DM/ha preand post-grazing, respectively. Pasture was well
managed during the study and pasture availability
was not limiting as indicated by the RPM reading
post-grazing being higher than 10. The milk yield,
milk composition, BW and BCS is represented
Proceedings of the 5th Australasian Dairy Science Symposium 2014407
in Table 2. The milk yield of cows on the PKE30
treatment was lower (P<0.05) than the control
(PKE0), however 4% FCM did not differ between
treatments (P=0.37). This was attributable to the
increase in milk fat content for cows on the PKE20
and PKE30 treatments (P>0.05). Milk protein and
lactose content did not differ between treatments
(P>0.05). Body weight did not differ between
treatments (P>0.05) but cows on the PKE10 and
PKE20 treatment lost more body condition than
cows on the PKE0 treatment (P<0.05). The slight
negative BW and BCS change were expected
due to decrease in pasture quality throughout the
growing season.
DISCUSSION
The chemical composition of PKE in this study
was within the ranges set by Alimon (2004). The
ME content of the concentrates decreased as the
level of PKE increased. This was expected as the
ME content of PKE (10.5 MJ ME/kg DM; Alimon,
2004) is lower than that of maize grain (ca. 14.2
MJ/kg DM; McDonald et al. 2002). The increase in
milk fat concentration of 9.3% and 14.3% for cows
on the PKE20 and PKE30 treatments respectively
may be due to the highly saturated fatty acid
composition of PKE (Dias, 2010) and was higher
than the 5% increase in milk fat concentration
with saturated fat supplementation reported by
(Schroeder et al. 2004). The difference in SCC
observed does not hold any biological significance
as the SCC values of all treatment cows were below
300 and 500 x 103 cells/ml of milk, which indicates
subclinical mastitis (De Villiers et al. 2000) and
milk price penalties in South Africa, respectively.
CONCLUSION
Partial replacement of maize with palm kernel
expeller sustained fat corrected milk production and
increased milk fat content of cows grazing kikuyu
pasture during summer.
ACKNOWLEDGEMENTS
The authors thank the Western Cape Agricultural
Research Trust and the Department of Agriculture
Western Cape for providing the funding, labour and
infrastructure.
Table 2: Milk yield, milk composition, body weight and body condition score of Jersey cows fed 6 kg (as
fed) concentrate per day, which contained either 0, 10, 20 or 30% palm kernel expeller, grazing kikuyu during
summer.
Parameter2
Milk yield (kg/cow/d)
4% FCM (kg/cow/d)
Milk composition
Milk fat (%)
Milk protein (%)
Milk lactose (%)
MUN (mg/dL)
SCC (x103 cell/mL)
Body weight (kg)
Before
After
Change
BCS (scale 1 – 5)
Before
After
Change
PKE0
15.6a
17.0
Treatment1
PKE10
PKE20
ab
15.4
15.3ab
17.4
17.7
PKE30
14.3b
17.0
4.63c
3.58
4.50
12.0c
134b
4.93abc
3.77
4.57
12.2bc
184ab
5.06ab
3.75
4.50
12.7abc
211a
418
415
-1.1
416
416
+0.6
2.19
2.28a
+0.09a
2.25
2.09b
-0.16b
SEM
P-value
0.4
0.4
<0.05
0.37
5.29a
3.76
4.52
13.2a
188ab
0.12
0.06
0.03
0.2
20
<0.01
0.10
0.45
<0.01
0.06
399
395
-3.4
410
407
-3.1
7.29
7.56
3.84
0.25
0.12
0.85
2.22
2.02b
-0.20b
2.19
2.12b
-0.07ab
0.04
0.04
0.04
0.69
<0.01
<0.01
Means within a row followed by different superscript letters differ significantly (P < 0.05)
PKE0 – concentrate containing 0% PKE; PKE10 – concentrate containing 10% PKE; PKE20 – concentrate
containing 20% PKE; PKE30 – concentrate containing 30% PKE; PKE – palm kernel expeller
2
FCM – fat corrected milk; MUN – milk urea nitrogen; SCC – somatic cell count; BCS – Body condition score
a-c
1
408
R. Meeske – Replacing maize with palm kernel expeller in dairy concentrates fed to Jersey cows grazing kikuyu pasture
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