Effects of sugar supplementation and roughage particle sizes on lower heat
stress and improve milk production of dairy cattle
Paserakung1, A., V. Pattarajinda1, M. Duangjinda1, and S. Katawatin1
1
Animal Science Department, Faculty of agricultural Khon Kaen University 40002, Thailand
Summary
Lower heat stress production is an application to increase dairy cattle performances. Eighteen
crossbreed Holstein cows (107 ± 52 DIM; 442 ± 42 kg of BW) were randomly assigned to a
randomized complete block design as a 2 x 3 factorial arrangement. The factors A was two
levels of rice straw particle sizes (15 cm and 1.3 cm) and the factor B was three levels of
sugar supplementation (0, 10, and 20 % DM). The results showed that reducing particle size
of rice straw decreased milk fat (4.0 vs 3.8 %). Increasing sugar at level 20 % decreased milk
fat (3.7 vs 3.9 and 4.0 %) and protein (3.0 vs 3.1 and 3.2). Higher milk lactose (4.9 vs 4.7 %)
was observed for the 10 % sugar level compare with the other 2 sugar level. But particle sizes
of rice straw and sugar levels did not have significantly difference among treatments (P >
0.05) even DMI, milk yield, glucose, BUN, T3, and RT (12.6 kg/d, 11.2 kg/d, 51.7 mg/dl,
22.8 mg/dl ,and 71.3 ng/dl, 39.2 0C). The numerical showed that sugar supplementation at 10
% increased DMI, milk yield, and T3 and decreased rectum temperature.
Key words: cattle, sugar, particle size, straw
Introduction
During heat stress condition, cow has exhibit in reduce feed intake and milk production.
Feeding rice straw can limit dry matter intake (DMI), and produce a greater heat of digestion,
Thus, finding the way to increase digestibility, DMI, milk yield and reduce heat stress is
necessary for dairy cow fed rice straw in hot season. Non fibrous carbohydrate (NFC) such as
starch and sugar are primary dietary sources of energy for dairy cow. The fermentation of
different NFC sources vary in digestion characteristics, profile of organic acid and microbial
protein yield (Hall and Herejk, 2001). In vitro study, replacing starch with 7.5 % sucrose in
TMR increased NDF digestibility (Vollimont et al., 2004). Adding sugar to the diet has been
reported to increase DMI, milk yield, and NDF digestibility (Broderick and Radloff, 2004).
Besides using sugar, reducing forage particle size has been reported to increase DMI, NDF
digestibility and milk yield (Vargar and Kolver, 1997). Therefore, the objectives of this study
were to determine the effects of sugar supplementation and roughage particle size on DMI,
milk production, blood metabolite and heat stress of dairy cow fed rice straw in hot season.
Materials and Methods
Eighteen crossbreed Holstein cows (107 ± 52 DIM; 442 ± 42 kg of BW) were randomly
assigned to a randomized complete block design as a 2 x 3 factorial arrangement. The diets
consist of two levels of rice straw particle sizes (course, 15 cm and fine, 1.3 cm) and three
levels of sugar supplementation (0, 10, and 20 % DM). Diets were fed 3 time daily (06.00,
11.00, 16.00) as TMR (Table 1). Feed offered and orts were measured and recorded daily
throughout experiment to calculate feed intake. Feed sample were analyzed for DM, CP, EE,
(AOAC, 1985) ADF and NDF (Van Soest et al., 1991). Cows were milked 2 time daily (05.00
and 16.00) and milk samples were analyzed for fat, protein, lactose, and solid not fat
(Lactostar, Funke – Dr.N. Gerber). Blood sample were analyzed for blood glucose (BG),
blood urea nitrogen (BUN) (Beckman – Coulter, Brea, CA) and triiodothyronine (T3). Rectum
temperature (RT) was measured by inserting a digital thermometer (Microlife, Model:
MT1611). Ambient temperature and relative humidity (RH) were monitored continuously in
the feed area. Ambient temperature and RH were used to calculate temperature humidity
index (THI) (West, 1994). All data obtained from the trials were subjected to the analysis of
variance procedure of statistical analysis system (SAS, 1988) according to a randomized
block design with 2 x 3 factorial arrangements of treatments. Means were separated by
Duncan New’s Multiple Range Test.
Table1. Feed ingredients and compositions of experimental TMR diets (DM basis).
Ingredient, % DM
CS0 CS10 CS20 FS0
FS10
FS20
Rice straw
35.0 35.0
35.0
35.0
35.0
35.0
1
Can sugar
0.0
10.0
20.0
0.0
10.0
20.0
Cassava chip
34.3 20.3
8.3
34.3
20.3
8.3
Corn, ground
10.0 14.0
16.0
10.0
14.0
16.0
Soybean meal
16.0 16.0
16.0
16.0
16.0
16.0
Coconut meal
1.5
1.5
1.5
1.5
1.5
1.5
Palm meal
1.5
1.5
1.5
1.5
1.5
1.5
Urea
1.1
1.1
1.2
1.1
1.1
1.2
Mineral and vitamin premix
0.6
0.6
0.6
0.6
0.6
0.6
Chemical composition, %
TDN
70.1 70.1
69.9
70.1
70.1
69.9
CP
14.2 14.2
14.5
14.2
14.2
14.5
EE
1.4
1.5
1.5
1.5
1.5
1.4
ADF
18.0 18.9
17.7
18.2
18.3
17.3
NDF
32.1 31.7
30.1
32.2
32.2
31.6
By – product from beverage industry contains 88 % of sucrose
1
Results and discussion
Dry matter intake, milk yield, and milk composition
Average ambient temperature, relative humidity and THI in this study were 29.8 0C, 71.7 %,
and 81.2. West (1999) reported that milk yield and TDN intake decline slightly when THI
reached 72 and declined sharply when THI exceeds 76. Dry matter intake, milk yield, and
milk composition are showed in table 2. DMI and milk yield were not affected (P > 0.05) by
reducing particle size of rice straw and sugar supplementation (average 12.6 and 11.2 kg/d).
However, the numerical showed that reducing particle size and sugar supplementation at 10 %
tended to increase intake and milk yield. Reducing particle size decreased milk fat (P < 0.05)
but not affected on milk protein and lactose (average 3.1 and 4.8 %). Supplemental sugar at
20 % tended to reduce milk fat and milk protein (P < 0.05). Higher milk lactose (4.9 and 4.7
%) was observed for the 10 % sugar treatment.
Blood glucose, blood urea nitrogen, triiodothyronine, and rectum temperature
BG, BUN, T3, and RT were showed in table 2. BG, there were not affected (P > 0.05) by
reducing particle size of rice straw and sugar supplementation (average 51.7, 22.8 mg/dl, 71.3
ng/dl, and 39.2 0C). However, the numerical showed that sugar supplementation at 10 %
tended to increase T3 and decrease RT, meaning that sugar diet may help to lower heat stress.
Conclusion
Reducing particle sizes of rice straw and sugar levels did not have significantly difference
among treatments (P > 0.05) even DMI, milk yield, glucose, BUN, T3, and RT. Reducing
particle size of rice straw and sugar supplementation at level 20 % decreased milk fat. Sugar
supplementation at 10 % increased milk fat, protein, and lactose. However, the numerical
showed that sugar supplementation at 10 % increased dry matter intake, milk yield, and T3
and decreased rectum temperature.
Table2. Intake, milk production, blood metabolite, and
diets.
Size
Sugar
Item
course fine
0
10
20
DMI, kg/d
12.8
12.4
12.2 12.7 12.9
DMI, %BW
2.8
2.9
2.7 3.1 2.8
Milk, kg/d
10.7
11.5
11.2 11.8 10.5
4% FCM, kg/d
10.8
11.2
10.4 11.2 10.0
Milk Composition, %
Fat
4.0a
3.8b
3.9a 4.0a 3.7b
Protein
3.1
3.1
3.1a 3.2a 3.0b
Lactose
4.7
4.8
4.7b 4.9a 4.7b
Solid not fat
8.8
8.9
8.9 8.8 8.8
Glucose, mg/dl
Pre - feeding
54.2
50.8
51.2 51.2 55.0
average 1-4h
52.3
51.2
53.2 50.9 50.9
BUN, mg/dl
Pre - feeding
20.1
23.5
19.0 21.6 24.9
average 1-4h
21.7
23.9
19.6 22.8 25.8
T3, ng/dl
Pre - feeding
67.7
62.6
62.1 68.8 64.6
average 1h-3h
72.3
70.3
71.0 72.5 70.5
๐
Rectum temperature ( C)
Pre - feeding
38.7
39.1
38.9 38.7 39.2
average 1h -4h
38.9
39.4
39.1 39.0 39.4
a, b
rectum temperature as influenced by
Effect
Sugar Size*Sugar
0.89
0.94
0.38
0.78
0.38
0.78
0.27
0.81
SEM
0.48
0.08
0.41
1.05
Size
0.72
0.51
0.35
0.50
0.06
0.05
0.04
0.28
0.005 0.005
1.00 0.004
0.34 0.004
0.51 0.77
0.29
0.38
0.72
0.51
3.34
2.2
0.22
0.54
0.45
0.39
0.53
0.63
3.45
3.23
0.26
0.42
0.27
0.21
0.97
0.92
6.41
6.23
0.36
0.7
0.62
0.95
0.44
0.43
0.18
0.19
0.11
0.01
0.07
0.27
0.16
0.21
Means within a row different superscripts differ (P<0.05)
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