Performance of growing heifers fed high intakes of
fresh or ensiled cassava residues from starch processing
supplemented with or without dried cassava foliage
Duong Nguyen Khang
Department of Animal Physiology and Biochemistry,
Faculty of Animal Husbandry and Veterinary Medicine,
Nong Lam University, Vietnam
duongnguyenkhang@yahoo.com
Abstract
Twenty growing heifers were used in the experiment to evaluate the effects on feed intake and growth rate of four diets: (FCR) fresh cassava residue ad libitium plus 1 kg DM napier grass per 100 kg LWt day-1, (FCR-DCF) fresh cassava residue ad libitium plus 0.5 kg DM rice straw plus 0.5 kg DM dried cassava foliage per 100 kg LWt day-1, (ECR) ensiled cassava residue ad libitium plus 1 kg DM napier grass per 100 kg LWt day-1 and (ECR-DCF) ensiled cassava residue ad libitium plus 0.5 kg DM rice straw plus 0.5 kg DM dried cassava foliage per 100 kg LWt day-1. All treatments were given daily 0.5 kg DM cotton seed meal and 20 g of a mixture of salt and minerals.
Dried cassava foliage supplementation slightly increased cassava residues intake. The highest total DMI was on the ensiled cassava residue diets. The live weight gain was significantly higher for the diets of fresh or ensiled cassava residues supplemented with dried cassava foliage versus the diet of fresh cassava residue without dried cassava foliage.
Fresh or ensiled cassava residues together with
dried cassava foliage could be an appropriate feed resource for
growing heifers.
Key words: Growing heifers, fresh or
ensiled cassava residues, dried cassava foliage,
intake
Introduction
In Vietnam cassava is the third crop after rice and maize, with about 337,000 ha planted in 2002 (FAOSTAT 2003). Cassava processing for starch has developed rapidly, especially in the rural areas near-by large towns and cities. It is estimated that about one third of cassava root production is now used for starch production (FAOSTAT 2003), but this operation is mainly at artisan level under farm household conditions. Besides getting benefits from selling cassava starch, farmers could get more benefits from raising animals based on using cassava residues as an available feed resource.
At the University of Agriculture and Forestry, cassava residues were ensiled with urea and fed as the basal diet (50% of the dry matter) to growing male crossbred dairy cattle (Danh and Preston1993). Growth rates were about 500 g per day and well below the potential of the diet and the animals. But under practical conditions, livestock performance is still very low because of lack of protein supplementation in traditional diets, especially for pigs and cattle and this problem becomes more serious in dry seasons. The residues from the processing of cassava roots to make starch and sodium glutamate are high in fermentable carbohydrate and moisture content, low in fibre and nitrogenous compounds. They are increasingly being fed to cattle and pigs in intensive confinement systems. However, the results have been poorer than would be expected in view of the high nutritive potential of these feed resources.
This study aimed
mainly at improvement of performance of growing heifers based on
introduction of high level feeding of cassava residues and dried
cassava foliage as the protein supplement in the diets.
Materials and methods
Location and animals
The experiment was conducted in 2003 at the experimental
farm of Nong Lam University, Ho Chi Minh City, Vietnam, near to the factories
that process cassava roots for manufacture of starch in
Thu Duc district. The aim was to evaluate the influence of fresh (FCR) or ensiled
(ECR) cassava residues in diets for growing heifers. Twenty growing
heifers of Sindhi breed, one and a half to two years of age, were
used in this study. The heifers were placed in individual stalls in
an open-sided barn. Clean and fresh water was available ad libitum
during the experiment (Table 1).
|
Table 1. Summary of materials in the experiment |
||||
|
|
Treatments |
|||
|
FCR |
FCR-DCF |
ECR |
ECR-DCF |
|
|
Number of animals |
5 |
5 |
5 |
5 |
|
Pre-experimental period (days) |
15 |
15 |
15 |
15 |
|
Experimental period (days) |
120 |
120 |
120 |
120 |
|
Range of initial LWt (kg) |
137 – 206 |
147 - 193 |
132 - 205 |
122 - 220 |
|
Fresh cassava residues |
Ad lib. |
Ad lib. |
- |
- |
|
Ensiled cassava residues |
- |
- |
Ad lib. |
Ad lib. |
|
RS (kg DM 100 kg-1 LWt day-1) |
- |
0.5 |
- |
0.5 |
|
NG (kg DM 100 kg-1 LWt day-1) |
1 |
- |
1 |
- |
|
DCF (kg DM 100 kg-1 LWt day-1) |
- |
0.5 |
- |
0.5 |
|
CSM (kg DM 100 kg-1 LWt day-1) |
0.5 |
0.5 |
0.5 |
0.5 |
|
Minerals and salt (g animal-1 day-1) |
20 |
20 |
20 |
20 |
|
NG = napier grass, RS = rice straw, DCF = dried cassava foliage, CSM = cotton seed meal. |
||||
Feed preparation
The rice straw was collected in the field, dried and stored for
feeding. All the cotton seed meal was bought at a local market on
one occasion. Napier grass was harvested at 42 days of growth, two
times per day in the morning (9 h) and afternoon (15 h) for the
experimental period.
The foliage for cassava hay was collected from one field when
harvesting the roots. The green tops were collected in lengths of
40 to 50 cm and chopped into pieces of 3 to 4 cm length and
sun-dried for 2 days by spreading on a plastic sheet placed on the
ground. The dried cassava foliage was stored in the bags for the
experiment.
Cassava processing for starch in villages of Thu Duc district
was mainly at artisan level and it took place for the whole year.
Average capacity of cassava processing was 700 kg of fresh cassava
per household per day. From that, farmers got 15 - 20% cassava
peel, 30 - 35% cassava residue as available feed resources for
cattle. Fresh cassava residues were ensiled with 3 % molasses in
sacks with a plastic bag inside to create good conditions for
fermentation. Duration of ensiling was 21 days.
Experimental design and
treatments
The experiment lasted 135 days. The first 15 days of the experiment were for adaptation of the growing heifers to the new diets. The recording period of the experiment was 120 days. Live weight gain of individual heifers was recorded by weighing on two consecutive days at 15 day intervals. Data on daily feed intake were taken every day throughout the experimental period. Feed samples for chemical composition were taken before feeding during the last three days of each 15 day interval.
Feeding management
The heifers were stratified by weight with four animals in
each group and within groups allotted randomly to one of the four
diets. Weighed feeds were offered to each individually-fed heifer. Napier grass and rice straw were offered twice daily at
10:00 and 14:00 h. Cotton seed meal, dried cassava foliage and 20 g
of a mixture of salt and minerals were offered together once daily
at 7:00 h. Fresh or ensiled cassava residues were offered ad libitum daily at 8:00, 12:00 and 16:00 h. The heifers had access to
the feeds during the whole day.
Measurements
Dry matter intake
All the feeds were weighed before feeding and supplied
separately to the heifers. Fresh or ensiled cassava residues were
offered ad libitum. Napier grass, straw and dried cassava foliage
were supplied at constant amounts. Refused feeds were weighed each
morning throughout the experimental period. The feeds were also
sampled for 3 days in each 15 day intervals and analyzed for dry
matter (DM) for calculation of daily dry matter intake (DMI),
according to the procedures of AOAC (1990).
Chemical composition of feed
ingredients
Feed samples were taken for analysis of dry matter (DM),
crude protein (CP), ether extract (EE), neutral detergent fiber
(NDF) and acid detergent fiber (ADF). The DM, CP and EE of the feed
samples were determined according to the procedures of AOAC (1990).
The NDF and ADF concentrations of feed samples were determined
according to the procedure of Van Soest et al (1991).
Live weight gain
The heifers were weighed on two consecutive days at
15 day intervals.
Statistical analysis
Data were analyzed as a completely randomized design using
the general linear model and pair-wise comparison in Minitab
Statistical Software version 13.31.
Results and discussion
Chemical composition of diet
ingredients
The chemical composition of the different feeds is given in Table 2. Dry matter, ash, CP, ADF and NDF were much lower in fresh and ensiled cassava residues than in dried cassava foliage, napier grass, cotton seed meal and rice straw. The CP and ash contents in the fresh and ensiled cassava residues used in this study were lower compared to the values of Men et al (2003). The differences between these studies might be due to the different cassava residues at harvesting and processing. Men et al (2003) conducted an experiment in which cassava residues were dried and used after root harvesting and processing. In the present study, the fresh and ensiled cassava residues were fed immediately to the heifers with high moisture content and relatively low in fibre. The dried cassava foliage in the present study was lower in CP, ash, ADF and NDF compared to the results of Wanapat et al (2001), but the same was found by Khang and Wiktorsson (2004) in pelleted cassava foliage.
|
Table 2. Chemical composition of experimental feeds |
||||||
|
|
DM (%) |
Composition of DM (g kg-1) |
||||
|
CP |
EE |
ADF |
NDF |
Ash |
||
|
Fresh cassava residue Ensiled cassava residue Rice straw Napier grass Dried cassava foliage Cotton seed meal |
16.8 18.8 88.6 17.5 91.4 90.2 |
14.2 18.6 46.4 74.6 204.3 364.6 |
11.2 14.8 11.7 19.8 65.8 18.2 |
84.4 98.2 410.2 404.5 368.2 324.2 |
126.4 138.2 622.6 731.6 496.6 212.3 |
11.3 13.9 184.2 61.4 70.2 78.4 |
Feed intake and live weight gain
Feed intake and live weight gain data of the heifers are
given in Table 3. No refusals were seen of napier grass, rice
straw, dried cassava foliage and cotton seed meal, which were fed
at constant amounts per 100 kg live weight on all treatments. The heifers normally consumed
the dried cassava
foliage and cotton seed meal in less than 15 minutes.
Supplementation of dried cassava foliage increased the intake of fresh or ensiled
cassava residues (P<0.001). The highest total DMI was on the dried cassava foliage diets
(FCR-DCF and ECR-DCF).
The weight gain of heifers on the diet of fresh cassava residues without supplementation of dried cassava foliage was low, the weight gain in the diets with dried cassava foliage was high (Table 3).
The type of cassava residues and the dried cassava foliage
supplement affected animal performance. Supplementation with dried
cassava foliage rased the intake of protein and improved the live weight gain. The highest daily live
weight gain was 315 g day-1 for the diet of ensiled
cassava residue and dried cassava foliage. Thuong and Pryor (1996), investigating the mature body weight of
Red Sindhi cattle in Vietnam, reported average weights of 275 kg
for cows and an average daily weight gain of heifers at 24 months
of age of 285 g day-1. These animals grazed only pasture
and were given 589 g day-1 of concentrate. Cattle breeds
that are heavier at maturity tend to gain weight faster than
smaller breeds. Felius (1985) reported a mature body weight of 340
kg for a Red Sindhi cow as a worldwide breed characteristic. Thus a
growth rate of 250 - 300 g day-1 can be considered as
typical for heifers of a breed with about 300 kg mature weight.
This was reached with the ensiled cassava residue ration and the
fresh cassava residue plus 0.5 kg of dried cassava foliage per 100
kg live weight, while the fresh cassava residue ration did not
result in satisfactory growth rates.
Conclusion
Fresh or ensiled cassava resides together with dried
cassava foliage is a suitable combination of feed resources for growing
heifers.
Acknowledgments
The author is grateful to the Swedish International Development
Authority (Sida/SAREC) for funding this study and Mr. Thanh for his
technical help.
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