Giá trị dinh dưỡng của một số thức ăn thông thường dùng cho bò sữa ở ngoại ô hà nội

Nutritive value of several forage commonly used for
dairy cattle in the suburb of Hanoi
Paul Pozy, Vu Chi Cuong, Le Van Ban, Doan Thi Khang
Armand Deswysen and Daniel Deharen





1. Introduction
Giving appropriate diets to dairy cattle, is supplying a well-balanced diet in
nutrients such as crude protein, minerals and vitamins in order to meet their
requirements for meat and milk production, and foetus development. Providing
enough feeds and ensuring good operation of digestive system, reducing
production cost of milk, means using useful available feedstuffs in local areas.

In order to calculate the quality of nutritients needed by dairy cow, It must
be known clearly the nutritive value of available feedstuffs. The nutritive value of
a feed is determined throughout the percentage of each nutrients in this feed
digested by animal Digestibilities are normally determined by using experiments
on sheep (in vivo digestibility) Aerts, et al., 1984; De Boever et al., 1987).

With the above target, from April 1999 to May - 2001, different kinds of
grass such as natural grass, cultivated grass and other feedstuffs used dairy cattle
in Hanoi suburban were implemented to predict the in vivo digestibility and energy
value of feeds.

2. Materials and methods
Digestibilities and nutritive value of feeds had analysed and determined in
Hanoi suburban. Experiments had made on 17 adult rams of Bach thao breed,
averaging 25 kg (7 sheeps during April, 1999; 10 sheeps during Oct, 2000).

Sheeps were shed in individually and fed ad libitum (at 9h am and 4h p.m.).

Grasses were cut and sun-dried for several hours and before giving to
sheeps. Grass were harvested at different periods and 6 kinds of grasses were used
in the experiments: fresh natural grass, Pennisetum purpureum, ensiled or
unensiled corn stover (after harvesting seed) and rice straw.

Natural grasses were cut in areas alongside rive dikes. The grasses were
mixture of several grasses but mainly: Cynodon dactylon, Panicum repurs,
Paspalum conzugatum. Corn stover was harvested at the periods after making
young corn seed or adult corn seed. Old corn stover was ensiled before giving to
sheeps.

There were 13 experiments, each experiment period lasted 31 day: 21 day
adaptation to foodstuff and crate and 10 day of measurements of daily voluntary
intake and extent of digestion as described by Burns et al., 1994 and Cochran and
Galyean, 1994)

The nutritive value of a feed is its net nutritive value used by animal for
their body weight maintenance and for productionpurpose. The net nutritive value
for producing milk is the metabolisable energy multiply with utilisation efficiency
of metabolisable energy for milk production (kl). Metabolisable energy (ME,
kcal/kg DM) of feed depends on its digestibility in animal and total energy
containing in the feed.

The protein value of a feed is its an amount of amino acids amin that was
adsorbed by the intestine. These amino acids come amin from two sources:
undegraged protein in rumen (PDIA) and protein of micro-organism (PDIM). The
quantity of micro-organism changes by feedstuff or diets. The quantity of PDIA
depens on nitrogen degraded in ruminant (PDIMN) or energy containing in the

feed (or diets) (PDIME).

Protein values digestible in the intestine: PDIN = PDIA + PDIMN

PDIE = PDIA + PDIME

3. Results and discussion
Despite the plant composition of grass mix, its changing quality, and
quantity of each grass in mix, there is a little change in the chemical composition
of natural grass, except percentage of crude protein: high in July and low in
January. It is also rich in nutrients in August (in table 1). This results indicated that
the harvesting period is very important.

The results also show that Pennisetum purpureum grass has similar
chemical compositions around year (table 1). Further more, two rice straws have
nearly the same chemical composition (table 1)

Natural grass harvested in the winter and rice straw have voluntary dry
matter intake (g DM/kg W
0.75
) which is similar or significant higher than that of
Setaria sp grass: 57g DM/kg W
0.75
(Pozy et al, 1995). Voluntary dry matter intake
(g DM/kg W
0.75
) of natural grass, harvested from April until Oct, is higher than
that of tropical grass (71g DM/ W
0.75
) (Xande et al, 1989). Pennisetum purpureum

grass harvested in 1999 has high quality.

The results of dry matter, organic matter, NDF digestibility were shown in
table 1. In the case of natural grasses, these data change significantly during each
periods around year; digestibilities of organic matter and NDF reduce from March
until August (48%, 55%, 56%; respectively) but they increase from June until Oct
(59%, 65%, 66%; respectively), and this results indicate that metabolism energy
(ME) and net energy value indicated by feed unit for lactating (UFL) of natural
grass are lowest in the period from March to August and of highest in the period
from June to Oct. Digestibilities of DM, OM, NDF and metabolism energy, net
energy value expressed by feed unit for lactation (UFL) of Pennisetum grass are
similar to that of natural grass harvested in Oct and of slightly changes during each
year. Pennisetum grass is rich in energy, but corn stover and rice straw are poor in
energy; and ensiled corn stover has the energy lower than that of hay.

Digestibility of nitrogen of Pennisetum grass is approximately 70% (table
2). In general, digestibility of nitrogen of this grass is higher than 65%. Total
protein (on DM basis) of natural grass is around 12% (natural grass cut at the time
from June to Oct). Digestibility of nitrogenr is lower than 50% if total crude
protein is lower than 10%. Ensiled corn stover, rice straw, hay, grass harvested at
the time from January to August has digestibility of nitrogen of about 55-58% for
dry grass, and about 55-58% for natural grass.

4. Conclusion
All grasses contain low level of energy value, natural grass in particularly,
so that they need to be added energy by supplying molasses. Addition 1-2 kg
molasses/head/day will helps balancing grass based diets.

Pennisetum grass can be used as a main roughage feed for dairy cow in
order to balance diet in the winter, it is better for getting enough voluntary dry

mate intake if ensiled Pennisetum grass was given. Agricultural by-products such
as ensiled corn stover or corn stover, can also include in dairy cattle’diets.

Rice straw can not be a main roughage in diets given to dairy cattle in areas
around Hanoi. If used rice straw replaces grass when lack of grass, it is needed to
be added feed rich in nutritients and crude protein.



Acknowledgements



To achieve this project, we had received useful helps from Dong Anh
Station Veterinary and Breeding Dairy Cattle Project of National Institute of
Animal Husbandry, as well as many students of Economy Department of HAU.
Thanks to the CUL, the Vietnamese and Belgian governments for funding his
study.

On this occasion, we also would like to give thanks to related organizations
and friends.



Summary



A series of feeding trials on sheep was conducted to determined the
nutritive value of several forage commonly used for dairy cattle in the suburb of

Hanoi. It is found that

there is a little change in the chemical composition of natural grass, except
percentage of crude protein: high in July and low in January. It is also rich in
nutrients in August.

Pennisetum purpureum grass has the similar chemical compositions around
year and two rice straws studied have nearly the same chemical composition.

All grasses contain low level of energy value, natural grass in particularly,
so that they need to be added energy by supplying molasses. Pennisetum grass can
be used as a main roughage feed for dairy cow in order to balance diet in the
winter



Table 1. Chemical compositions of several kinds of grass



Foodstuff
DM

(%)

Organic
mate (%)

NDF

(%)

CP

(%)

Natural grass

January

March

April

June

August

Oct

Dried grass



22.10

20.40

49.70

27.50

32.30

21.60

86.90



83.30

79.60

88.10

86.80

85.10

83.50

86.50



63.10

66.10

64.70

63.00

70.40

65.80

68.10



10.70

14.80

12.70

19.30

11.10

12.70

10.90

Penniseutum purpureum

Experiment in 1999 year

Experiment in 2000 year



17.00

15.90



83.20

84.50



64.60

63.20



13.30

14.10

Silaged corn term (after harvested seed)

23.80

93.10

74.10

9.00

Corn term (after harvested young seed)

8.70

87.10

73.00

8.70

Rice straw

Experiment in 1999 year

Experiment in 2000 year



92.80

85.10

82.30

84.90



71.50

73.20



7.40

5.10







Table 2. Voluntary dry mate intake, digestibilities and nutritive value of several grasses





Digestibilities (%)

Nutritive value (g/kg DM)



Voluntary
dry mater
intake
(gDM/kgW
0.75)

Dry
mater

Organic
mater

NDF

Nitrogen

PDIA

PDIN

PDIE

UFL

Natural grass

January
March

April

June

August

Oct

Dry grass

58.33

52.99

72.79

80.38

75.27

83.16

75.31

57.4

46.7

53.5

61.8

49.3

57.4

57.9

63.2

54.9

58.3

66.2

54.6

64.4

62.4

65.6

57.6

54.1

68.7

55.7

64.4

63.6

55.9

67.7

66.7

74.3

55.5

66.1

58.7

29

47

44

100

26

44

33

59

88

80

126

57

79

63

74

82

85

117

58

89

78

0.67

0.53

0.65

0.76

0.56

0.70

0.69

Penniseutum purpureum

1999

2000

68.2

62.6

65.9

66.1

69.9

70.4

72.9

72.6

70.9

69.2

53

73

90

91

99

102

0.76

0.78

Corn stover

After
harvesting
seed

NS

56.8

59.1

62.8

46.9

2

38

51

0.66

After
harvesting
young seed

63.8

58.3

67.1

70.6

49.4







0.75

Rice straw

1999

2000

40.7

38.9

44.4

43.6

46.5

48.6

53.1

57.8

40.2

-

.11

3

32

11

43

33

0.43

0.46