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

1Animal Science Department, Faculty of agriculturalKhon 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 strawdecreased 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 vitrostudy, 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 objectivesof 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 recordeddaily 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 samplewere analyzedfor 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
Can sugar1 / 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

1By – product from beverage industry contains 88 % of sucrose

Results and discussion

Dry matter intake, milk yield, and milk composition

Average ambient temperature, relative humidity and THI in this study were29.8 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, bloodurea 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 rectum temperature as influenced by diets.

Size / Sugar / Effect
Item / course / fine / 0 / 10 / 20 / SEM / Size / Sugar / Size*Sugar
DMI, kg/d / 12.8 / 12.4 / 12.2 / 12.7 / 12.9 / 0.48 / 0.72 / 0.89 / 0.94
DMI, %BW / 2.8 / 2.9 / 2.7 / 3.1 / 2.8 / 0.08 / 0.51 / 0.38 / 0.78
Milk, kg/d / 10.7 / 11.5 / 11.2 / 11.8 / 10.5 / 0.41 / 0.35 / 0.38 / 0.78
4% FCM, kg/d / 10.8 / 11.2 / 10.4 / 11.2 / 10.0 / 1.05 / 0.50 / 0.27 / 0.81
Milk Composition, %
Fat / 4.0a / 3.8b / 3.9a / 4.0a / 3.7b / 0.06 / 0.005 / 0.005 / 0.29
Protein / 3.1 / 3.1 / 3.1a / 3.2a / 3.0b / 0.05 / 1.00 / 0.004 / 0.38
Lactose / 4.7 / 4.8 / 4.7b / 4.9a / 4.7b / 0.04 / 0.34 / 0.004 / 0.72
Solid not fat / 8.8 / 8.9 / 8.9 / 8.8 / 8.8 / 0.28 / 0.51 / 0.77 / 0.51
Glucose, mg/dl
Pre - feeding / 54.2 / 50.8 / 51.2 / 51.2 / 55.0 / 3.34 / 0.22 / 0.45 / 0.53
average 1-4h / 52.3 / 51.2 / 53.2 / 50.9 / 50.9 / 2.2 / 0.54 / 0.39 / 0.63
BUN, mg/dl
Pre - feeding / 20.1 / 23.5 / 19.0 / 21.6 / 24.9 / 3.45 / 0.26 / 0.27 / 0.97
average 1-4h / 21.7 / 23.9 / 19.6 / 22.8 / 25.8 / 3.23 / 0.42 / 0.21 / 0.92
T3, ng/dl
Pre - feeding / 67.7 / 62.6 / 62.1 / 68.8 / 64.6 / 6.41 / 0.36 / 0.62 / 0.44
average 1h-3h / 72.3 / 70.3 / 71.0 / 72.5 / 70.5 / 6.23 / 0.7 / 0.95 / 0.43
Rectum temperature (๐C)
Pre - feeding / 38.7 / 39.1 / 38.9 / 38.7 / 39.2 / 0.18 / 0.11 / 0.07 / 0.16
average 1h -4h / 38.9 / 39.4 / 39.1 / 39.0 / 39.4 / 0.19 / 0.01 / 0.27 / 0.21

a, b Means within a row different superscripts differ (P<0.05)

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